ICRC 2025 - The Astroparticle Physics Conference

14 Jul 2025, 16:00 → 24 Jul 2025, 19:00 Europe/Zurich

CICG - International Conference Centre - Geneva, Switzerland

It is a great pleasure to welcome you to the 39th International Cosmic Ray Conference (ICRC 2025) in Geneva, Switzerland.

The ICRC conferences are held biennially since 1947 by the Commission C4 (Astroparticle Physics) of the International Union of Pure and Applied Physics (IUPAP*). The main topics are Cosmic Ray Physics, High Energy and Gamma-Ray Astrophysics, Neutrino Astrophysics, Dark Matter, Solar and Heliospheric Physics, Multi-messenger and Gravitational Wave Astronomy. 

The Local Organizing Committee (LOC), the Scientific Organiszing Committee (SOC), and the International Advisory Committee (IAC) are jointly organizing ICRC 2025. 

All the members of the LOC are proud to host ICRC 2025 and welcome you in Geneva to have great and fruitful time during the conference.

URL:  http://icrc2025.unige.ch

*Please see here about IUPAP and its conference policies.

 

Sponsors and Organisations

 

 

Circular#1 Nov 20, 2024.pdf

Circular#2 Dec 15, 2024.pdf

Flyer-Exhibitors.pdf

proceedings_template.tar

Monday 14 July

16:00 → 18:00 Registration

Tuesday 15 July

08:00 → 09:00 Registration

08:30 → 09:00 Coffee

09:00 → 09:40 Opening: Welcome

Convener: Roland Walter (University of Geneva)

09:00 Welcome

Speaker: Roland Walter (University of Geneva)

09:08 Message from the University of Geneva

09:14 Welcome from CERN

09:19 Message from the State of Geneva

09:25 Message from the IUPAP president

Speaker: Sunil Gupta (Tata Inst. of Fundamental Research (IN))

09:30 Remark from the chair of the International Advisory Committee IUPAP C4

Speaker: Ralph Engel (KIT)

09:40 → 10:40 Opening: Awards

Convener: Ralph Engel (KIT)

09:40 IUPAP Early Career Scientist Prizes I

Speaker: Ralph Engel (KIT)

09:50 IUPAP Early Career Prizes II

Speaker: Ralph Engel (KIT)

10:00 O'Ceallaigh Medal

Speaker: Ralph Engel (KIT)

10:10 Babha Award

Speaker: Ralph Engel (KIT)

10:20 Shakti Duggal Award

Speaker: Jamie Holder (University of Delaware)

10:30 Yodh Prize

Speaker: Steve Barwick

10:40 → 10:50 Opening: Concluding remarks

Conveners: Ralph Engel (KIT), Roland Walter (University of Geneva)

10:50 → 11:50 Plenary session

10:50 Atmospheric Neutrino Oscillations: New Results and the Path Forward

Atmospheric neutrinos have been crucial in advancing our knowledge of neutrino oscillations. Notably, this source of neutrinos provided one of the first evidences of this phenomenon in the late 20th century. Since then, significant progress has been made, bringing us closer to the so-called precision era of neutrino oscillation physics. SuperK has demonstrated for over three decades that Cherenkov detectors are a powerful instrument for studying neutrinos produced in the atmosphere. This success has inspired a new generation of experiments employing similar technology on a larger scale, whose main goal is to resolve one of the major open questions in particle physics: the neutrino mass ordering. In this talk, I will present an overview of atmospheric neutrino oscillations, highlighting the latest experimental results, recent phenomenological developments, and future prospects in the field.

Speaker: Dr Alfonso Andres Garcia Soto (IFIC)

11:20 LIGO,VIRGO,KAGRA - Barry Barish

11:50 → 12:00 Opening: Group photo

12:00 → 13:20 Lunch

12:00 → 13:20 PO-1: Posters installation

13:20 → 14:50 CRD: experimental results: proton & He

13:20 Direct measurement of the all-particle spectrum up to the PeV region with CALET on the International Space Station

The CALorimetric Electron Telescope (CALET) is a space-based experiment performing direct cosmic-ray observations aboard the International Space Station. Since the start of observations in October 2015, CALET has been continuously collecting scientific data for more than nine years. The instrument is capable of measuring individual cosmic-ray nuclei, covering a wide energy range from a few tens of GeV to the PeV scale, and can precisely identify the charge of each particle. In this study, we present the all-particle cosmic-ray energy spectrum measured with CALET. The spectrum extends close to the 1 PeV region, where indirect measurements have covered higher energies. CALET's direct measurements in this energy range provide valuable insights into the acceleration and propagation of high-energy cosmic rays. In particular, this spectrum is expected to provide new insights that complement indirect measurements of the Knee structure in the all-particle energy spectrum.

Speaker: Dr Yosui Akaike (Waseda University)

13:35 Measurement of the all-particle energy spectrum up to 0.5 PeV with DAMPE

The DArk Matter Particle Explorer (DAMPE) is a space based detector operating since its launch in December 2015. The primary goals of the mission include the measurement of the cosmic e+e − spectrum, the high energy gamma-ray astronomy, and the analysis of the flux and composition of cosmic ray protons and nuclei from tens GeV up to several hundreds TeV.
This study presents a direct measurement of the all-particle cosmic ray energy spectrum using data collected by DAMPE since January 2016. A dedicated analysis framework has been developed, which implements a less restrictive event selection criteria compared to those in single species spectral measurements. In particular, without applying charge selection and by using looser tracking requirements, this analysis enables the collective study of events of all particle species. This approach is designed to minimize systematic biases while maximizing statistical significance, allowing for measurements at higher energies than those achievable through individual species analyses.
This measurement results in providing the all-particle flux over an energy range spanning from few hundreds GeV to the sub-PeV domain. Thus, it approaches the so-called spectral knee with unprecedented precision for a space-based experiment, while having a wide energy overlap with ground-based observations. Possible features in the all-particle spectrum can then be studied and compared with single species spectral breaks and galactic cosmic ray acceleration/propagation models. The preliminary results of this analysis will be presented and discussed.

Speaker: Irene Cagnoli (Gran Sasso Science Institute (IT))

13:50 Revisiting the Cosmic Ray knee: new insights from LHAASO

Recently, LHAASO has performed precise measurements of the all-particle spectrum and the mean logarithmic mass $\langle \ln A \rangle$ of cosmic rays at energies around the knee (~4 PeV). These data provides an unprecedented opportunity to test models of Galactic CR acceleration and propagation, bridging direct and indirect measurements for the first time. In this work, we develop a phenomenological model of CR spectrum and composition, in which CRs experience rigidity-dependent effects during their propagation in the Galaxy. We find that a single population of sources with propagation effects can adequately explain spectral data around the knee, from 1 TeV to 30 PeV. However, the composition extrapolated from direct measurements requires the spectrum at the knee to be dominated by helium, contradicting LHAASO measurements of $\langle \ln A \rangle$. We discuss possible solutions to this tension, including a previously theorized second Galactic population providing primarily high-energy protons, and non-rigidity-dependent spectral features. We take special care to include in our model subdominant elements that are not resolved by direct experiments but provide a non-negligible total contribution to the all-particle spectrum. Using our model we provide up-to-date constraints on the properties of the spectral break, namely the energy scale and the change of slope, and compare them to several theoretical predictions.

Speaker: Igor Vaiman (Gran Sasso Science Institute, INFN-Laboratori Nazionali del Gran Sasso)

14:05 Extended measurement of the proton spectrum with CALET on the International Space Station

The Calorimetric Electron Telescope (CALET) is carrying out direct measurements of the main components of high energy cosmic rays up to ~1 PeV in order to obtain systematic understanding of cosmic ray acceleration and propagation. The detector consisting of a charge detector, an imaging calorimeter, and a total absorption calorimeter, is located on the International Space Station. The thickness of the calorimeter is equivalent to 30 radiation lengths and to ~1.3 proton interaction lengths. Data taking started in October 2015 and continues stably without any serious troubles.
We present the latest result of our proton spectrum analysis in the energy region from 50 GeV to more than 100 TeV. The energy resolution of protons is 30-40%. Compared to our previous result published on Physical Review Letters in 2022, the statistics has been increased by more than a factor of 1.3 and the energy range has been expanded.

Speaker: Kazuyoshi Kobayashi (Waseda university)

14:20 Cosmic ray proton spectrum towards PeV with 9 years of DAMPE data

Protons are the most abundant component of Cosmic Rays (CRs), predominantly of primary origin. Due to their relatively high flux compared to the other CR elements, they constitute a unique footprint of the high-energy CR phenomena that can be probed with space experiments. Recent results of the DAMPE mission on the combined proton plus helium flux indicate the presence of a new structure – a spectral hardening at about 150 TeV. It is now of utmost importance to measure individual CR
proton spectrum at such energies, gradually approaching the PeV frontier and the CR knee. This will provide an essential piece of information for identifying the high-energy CR origin in our galaxy.

Speaker: Andrii Kotenko (Universite de Geneve (CH))

14:35 Measurements of cosmic-ray proton and helium spectra from the ISS-CREAM experiment

The Cosmic Ray Energetics And Mass for the International Space Station (ISS-CREAM) payload was developed to measure the elemental spectra for a charge range of Z = 1 to 26, with an energy range from ~ 10$^{12}$ eV to ~ 10$^{15}$eV. Launched in August 2017, the ISS-CREAM payload successfully collected data for 539 days until February 2019. The ISS-CREAM instrument consists of several particle detectors: a Silicon Charge Detector (SCD) for charge measurements and a calorimeter (CAL) with carbon targets for energy measurements. It also includes a top counting detector (TCD), a bottom counting detector (BCD), and a boronated scintillator detector (BSD) to help separate electrons from protons. For this analysis, SCD and CAL were used for the charge and energy measurement, respectively, while TCD/BCD and CAL were used for the trigger. The ISS-CREAM proton spectrum has been reported in the energy range of 1.6 - 655 TeV. This proton spectrum deviates from a single power-law, softening at ~9 TeV. This study presents the helium spectrum from the ISS-CREAM experiment in the energy range of 2.7 TeV to ~1.1 PeV.

Speaker: Gwangho Choi

13:20 → 14:50 CRI: anisotropy

13:20 A composition-informed search for large-scale anisotropy with the Pierre Auger Observatory

The large-scale dipole structure in the arrival directions of ultra-high-energy cosmic rays above 8 EeV observed by the Pierre Auger Collaboration is a well-established anisotropy measurement. This anisotropy is understood to be of extragalactic origin, as the maximum of the dipolar component is located $\sim115^\circ$ away from the Galactic Center. Cosmic rays interact with background radiation and magnetized regions along their path from their sources to Earth. These interactions, which depend on the cosmic-ray energy, charge and mass composition, give rise to different propagation horizons and deflections that are expected to lead to different anisotropies in the arrival directions of cosmic rays at Earth.

In this contribution, we investigate for the first time the composition signature on the large-scale anisotropy taking advantage of composition estimators obtained for the data gathered with the surface detector. A way of probing for composition signatures in anisotropy patterns is to divide the data into composition-distinct subsets. In a simulation library, we evaluated the possibility of measuring a separation in total dipole amplitude between two such populations of the measured dataset under a source-agnostic model. Following a positive prospect, the Auger Phase 1 data set was separated into "light" and "heavy" subsets. We present the 3D dipole for each population, highlighting a separation in both amplitude and direction. The observed dipole amplitude for the light population is larger than that of the overall data, supporting the hypothesis of a composition signature on large-scale anisotropies.

Speaker: Geraldina Golup

13:35 New full-sky studies of the distribution of ultra-high-energy cosmic-ray arrival directions

Ground-based full-sky studies of the angular distribution of arrival directions of ultra-high-energy cosmic rays require combining data from different observatories, such as the Pierre Auger Observatory (Auger) and the Telescope Array (TA), because no single array can cover all declinations. A working group comprising members from the Auger and TA collaborations has been tasked with performing such studies for more than a decade and has found several indications of full-sky anisotropies. Here, in addition to an overview of previous results, we apply new analysis techniques to data that were previously only used on simulations.

Speaker: Alberto Gálvez Ureña

13:50 Update on the intermediate arrival-direction analyses of the Pierre Auger Observatory

We present an update on the arrival-direction analyses conducted on intermediate angular scales using the complete Phase I data of the Pierre Auger Observatory up to the end of $2022$ with a total exposure of $135,000\,\text{km}^2\,\text{sr}\,\text{yr}$. We will show the arrival-direction distribution of the ultra-high-energy cosmic rays along the supergalactic plane above $20\,\text{EeV}$, and an update in the search for magnetically-induced signatures in the arrival directions. Furthermore, we present the potential of introducing event-per-event mass estimators to enhance arrival-direction analyses on small to intermediate angular scales. To achieve this, we will take advantage of two estimators working on the response of the surface detector: an analytical fit based on air-shower-universality and a deep-neural network.

Speaker: Lorenzo Apollonio

14:05 Tests of anomalous correlations between ultra-high-energy cosmic rays and BL Lac type objects with the Telescope Array data

Observations made by the High Resolution Fly's Eye detector in stereoscopic fluorescent mode revealed correlations between arrival directions of ultra-high-energy cosmic rays and positions of distant BL Lac type objects (Gorbunov et al. 2004, Abbasi et al. 2005). They implied the existence of non-deflected particles travelling for cosmological distances, which was hard to explain within standard physics and astrophysics. These correlations have not been conclusively tested with independent data. Here we present the results of such tests performed with the use of two different methods and Telescope Array data.

Speaker: Mrs Mariia Kudenko (Institute for Nuclear Research Russian Academy of Science)

14:20 Galactic Cosmic Ray Anisotropy: Calculations of the Angular Power Spectrum

Simulations of the cosmic-ray (CR) anisotropy down to TeV energies are presented, using turbulence parameters consistent with those inferred from observations of the interstellar medium. We compute the angular power spectra $C_{\ell}$ of the CR anisotropy obtained from the simulations. We show that the power spectrum depends on CR energy, and that it is sensitive to the location of the observer at small $\ell$. It is found to flatten at large $\ell$, and can be modelled by a broken power-law, exhibiting a break at $\ell \approx 4$. Our computed power spectrum at $\sim 10\,$TeV fits well HAWC and IceCube measurements. Moreover, we calculate all coefficients of the spherical harmonics and compute the component of the angular power spectrum projected onto the direction of the local magnetic field line. We find that deviations from gyrotropy become increasingly important at higher CR energies and larger values of $\ell$. We also present the simulation results of CR anisotropy in Bohm turbulence. The differences in the angular power spectrum of two types of turbulence, along with comparisons to experimental observations, can provide insights into the structure of turbulent magnetic fields in the interstellar medium (ISM) surrounding the Earth.

Speaker: Wenyi Bian

14:35 Measurements of cosmic-ray anisotropy using LHAASO-WCDA

The cosmic-ray anisotropy is now used to help unveil nearby cosmic-ray accelerators and their local propagation environment. The LHAASO-WCDA experiment is composed of three water ponds. It covers a total detection area of 87000 m^2, which makes it an ideal detector for measuring the cosmic-ray anisotropy from hundreds of GeV to ∼PeV. In this talk, we present the measurements of the cosmic-ray anisotropy using three years of WCDA data. We extended our measurement to the lower energy, about 600 GeV. We find a significant energy dependence of the dipole component of the sidereal-time anisotropy below several TeV. Meanwhile, we also find the remarkable influence of solar activities on the solar-time anisotropy at sub-TeV.

Speaker: Wei Liu (ihep)

13:20 → 14:50 CRI: miscellaneous

13:20 Reconstruction of the History of Galactic Cosmic Rays via In Situ Production of 14CO in Antarctic Ice

Galactic Cosmic Rays (GCR) are a common background for measurements of solar activity. Measurements of long-lived isotopes in meteoritic data indicate the GCR flux has been constant for several Myr, but these measurements have relative systematic uncertainties exceeding 30%. By using deep-ice carbon-14 extracted from the Antarctic ice sheet at Dome C, we can reconstruct changes in the GCR flux over the past ~7 kyr with much higher precision than previously achieved. We present a model of the relationship between cosmic rays at the top of the atmosphere and 14CO formed in Antarctic ice using atmospheric and in-ice particle cascades, measurements of muon interaction cross-sections, and ice flow models to track the formation and accumulation of carbon-14. We will describe future applications of the model to 14CO measurements obtained at Dome C in early 2025 and forecast constraints on the recent history of the GCR flux.

Speaker: Walter Cook (University of Rochester)

13:35 Searching for Signs of Cosmic Ray Ensembles with the GELATICA Array

The GELATICA experiment (GEorgian Large-area Angle and TIme Coincidence Array) comprises several cosmic ray detector arrays located in two cities in Georgia. These observatories are designed to detect Extensive Air Showers (EAS) with high-precision timing and determine the arrival directions of cosmic ray showers. GELATICA is part of the CREDO collaboration (Cosmic Ray Extremely Distributed Observatory), with its primary objective being the search for Cosmic Ray Ensemble (CRE). In this work, we present an analysis of data collected over the past few years, examining detector performance, the distribution of recorded signals, and the potential for simultaneous detections across multiple arrays. So far, no CRE candidate events have been identified.

Speaker: Revaz Beradze (Andronikashvili Institute of Physics)

13:50 Cosmogenic Background Characterization for the Colorado Underground Research Institute (CURIE)

Cosmic ray secondaries produced in Earth's atmosphere present a dominant background in many experiments and equipment benchmarking efforts, especially for those requiring high levels of sensitivity. For such experiments and equipment testing, underground research facilities are an essential asset. These facilities are sought after due to the rock overburden, which provides natural protection from ionizing cosmogenic radiation, such as the near-elimination of cosmogenic muons. However, for many efforts such as dark matter searches or neutrinoless double beta decay experiments, the surviving cosmogenic muon and muon-induced events still present a significant background. One way to characterize and address these backgrounds, especially for R&D and equipment benchmarking, is to move to shallow underground facilities such as the new Colorado Underground Research Institute (CURIE). In this talk, we present the characterization of cosmogenic muon and secondary backgrounds for CURIE located in the Edgar Experimental Mine in Idaho Springs, CO. The underground muon flux was simulated using the MUTE software package and subsequently validated with direct measurements, yielding a 700x reduction relative to the sea level surface muon flux. Additionally, a new depth-intensity relationship was developed to interpret the overburden, resulting in an equivalent overburden of 415 meter-water-equivalent (m.w.e.) for CURIE. Lastly, we discuss the muon-induced secondaries at the rock-cavern boundary which were simulated by coupling the underground muon angular and energy spectrum from MUTE with Geant4.

Speaker: Dakota Keblbeck

14:05 Advancements in the IceAct Energy Spectrum Analysis

The IceAct telescopes are Imaging Air Cherenkov telescopes installed as part of the IceCube Neutrino Observatory at the geographic South Pole. They consist of a 61 pixel camera and are small and robust to withstand the harsh environmental conditions. IceAct detects Cherenkov light produced by cosmic-ray particles with energies above approximately 10TeV interacting inside the atmosphere, which is complementary to the measurement of the air shower at the surface by IceTop and the high-energy muons in the deep ice. Two telescopes have been taking data since 2019 with a conservative estimated duty cycle of around 10%. A graph neural network is used to reconstruct the basic air shower properties, like geometry and primary energy. This work focuses on the current progress in analyzing the energy spectrum of cosmic rays using IceAct data.

Speaker: Larissa Paul

14:20 Calibration Progress of the LHAASO-WFCTA based on Laser Calibration System and Atmospheric Monitoring

The Wide Field-of-view Cherenkov Telescope Array (WFCTA) at the Large High Altitude Air Shower Observatory (LHAASO) detects cosmic-ray-induced air showers by measuring Cherenkov light produced by secondary particles in the atmosphere. Precise reconstruction of primary cosmic-ray properties necessitates rigorous calibration of atmospheric attenuation effects and telescope response. This study presents an integrated calibration system deployed at the LHAASO site, comprising four fixed laser calibration stations, a 20-meter meteorological tower, and a sun photometer: 1) The meteorological tower provides real-time atmospheric densityderived from temperature and humidity measurements; 2) The sun photometer acquires daytime vertical aerosol optical depth; 3) A novel laser calibration system employs a multi-angle scanning strategy, utilizing adjustable azimuth (0–360°) and elevation (0–90°) to systematically scan the WFCTA’s full field-of-view (14°×16°). Results demonstrate that this synergistic approach effectively decouples atmospheric attenuation from detector response, ensuring reliable energy reconstruction for TeV–PeV cosmic rays. This work establishes a benchmark for atmospheric and instrumental calibration in ground-based cosmic-ray observatories.

Speaker: Dr Qinning Sun (IHEP)

14:35 Probing Ancient Cosmic Ray Flux with Paleo-Detectors and the Launch of the PRIµS Project

Paleo-detectors offer a unique opportunity to probe the long-term history of cosmic ray-flux, potentially revealing evidence of nearby supernovae and other high-energy astrophysical events. This technique relies on the persistent damage tracks left in natural minerals by nuclear recoils induced by cosmic ray secondaries, providing an integrated record of particle flux over geological timescales. In this contribution, we present our recently published work demonstrating that evaporites formed during the Messinian Salinity Crisis (~6 Myr ago) could provide an ideal natural archive for secondary cosmic ray interactions. By modeling the density of nuclear recoil tracks preserved in these minerals and taking into account the deposition and shielding rate in the geological event, we show that percent-level variations in the primary cosmic ray flux could be detected, extending the reach of paleo-detectors beyond dark matter and neutrino searches to cosmic ray paleo-astrophysics. We also introduce PRIµS, an INFN-funded experimental effort that is the natural extension of our phenomenological work. Using high-throughput optical microscopy and plasma etching techniques, PRIµS aims to analyze a variety of samples, with a focus on halite and other evaporites, with the goal of validating theoretical models and refining background estimates for future paleo-detector applications.

Speaker: Claudio Galelli (INFN Milano)

13:20 → 14:50 GA: cosmic background

13:20 Probing the extragalactic infrared background with LHAASO

: The extragalactic background light (EBL) contains all the radiation emitted by nuclear and accretion processes in stars and compact objects since the epoch of recombination. Measuring the EBL density directly is challenging However, gamma-ray astronomy provides an alternative approach to indirectly studying the EBL through the observation of gamma-ray absorption in the spectra of distant blazars. The Large High Altitude Air Shower Observatory (LHAASO), with its unique capabilities—near full duty cycle, wide field of view, and high sensitivity—is exceptionally well-suited for exploring the EBL, particularly in the near to mid-infrared region ( wavelengths of 1 to 100 micrometers). In our presentation, we will discuss the methods we employed for this analysis and share our preliminary findings based on LHAASO's observations.

Speaker: Zhiguo Yao (IHEP, Beijing)

13:35 Investigating the gamma-ray opacity and searching for additional contributions to the EBL with H.E.S.S.

The intrinsic gamma-ray flux from extragalactic sources in the very-high-energy (VHE; E>100GeV) regime is subject to attenuation due to interactions with photons of the extragalactic background light (EBL), leading to pair production. Consequently, the Universe is expected to appear opaque to VHE photons above certain energy thresholds, depending on the redshift of the source. An oscillation of VHE photons into axion-like particles (ALPs) with masses below $\sim 10^{-6}$ eV in the presence of ambient magnetic fields could reduce the opacity, as ALPs can propagate unimpeded over cosmological distances. On the other hand, heavier ALPs with masses around 10 eV that contribute to the dark matter density of the Universe could decay into two photons and contribute to the EBL, thereby increasing the gamma-ray opacity. In this study, we analyze a large sample of gamma-ray spectra obtained with the High Energy Stereoscopic System (H.E.S.S.) and the Fermi-Large Area Telescope to search for these ALP signatures. Two independent approaches are adopted to explore distinct regions of the ALP parameter space. The first approach models ALP-induced spectral upturns in gamma-ray observations, while the second investigates the effect of ALP decay on the EBL and its measurable impact on blazar spectra.

Speaker: Atreya Acharyya (University of Southern Denmark)

13:50 Gamma-ray cosmology in the upcoming CTAO era

The history of photon production and galaxy evolution since the epoch of reionization is encoded in the extragalactic background light (EBL). Above an energy threshold, $\gamma$-rays can interact with the optical and infrared photons that dominate the EBL, resulting in an absorption imprint in the spectra of extragalactic sources. The combined observations of the current generation of ground-based $\gamma$-ray instruments have recently enabled the first purely parametric $\gamma$-ray measurement of the EBL spectrum at $z=0$ that is independent of models of the evolution of the EBL with redshift. In this work, we extend this $\gamma$-ray cosmology analysis to the next generation of $\gamma$-ray observatories, the Cherenkov Telescope Array Observatory (CTAO), which will bring improved sensitivity and energy resolution, and broader energy range. Using simulations of over 3000 hours of observations, we demonstrate the unprecedented precision across the EBL spectrum that CTAO could achieve, and we explore the implications of such a precision for $\gamma$-ray cosmology. We show the potential for CTAO to measure $H_0$, the expansion rate of the Universe at $z=0$, as well as to place constraints on diffuse emissions from exotic processes.

Speaker: Lucas Gréaux (Fakultät für Physik & Astronomie, Ruhr-Universität Bochum, D-44780 Bochum, Germany)

14:05 Exploring contribution of Kilonovae to the MeV diffuse gamma-ray background

The diffuse gamma-ray background (DGRB) measured by various telescopes spans over a wide energy range from keV to around TeV. In the energy range (100 MeV-820 GeV), the DGRB can be explained by sources such as blazars and star forming galaxies. Whereas in the lower energies up to around 0.3 MeV, the dominant sources are found to be active galactic nuclei and Seyfert galaxies. However, in the intermediate MeV energies (MeV DGRB), the sources in addition to the supernovae are not yet fully explored due to lack of MeV observation data. In this work, we explore the contribution of gamma-ray emission from r-process nucleosynthesis in Kilonovae to the MeV DGRB. Finally, we analyse the potential measurement of this MeV DGRB Kilonovae signal with future MeV missions.

Speaker: Dr PRANTIK SARMAH (Institute of High Energy Physics, Beijing)

14:20 (Remote) Measuring the Infrared Extragalactic Background Light with VHE Gamma Rays and Fermi-LAT

The extragalactic background light (EBL) encodes the cumulative radiation from extragalactic sources across ultraviolet to infrared wavelengths, serving as a key probe of galaxy formation and cosmic evolution. This study enhances previous EBL reconstructions by incorporating the Spectral TeV Extragalactic Catalog (STeVECat), expanding the sample from our previous study to include a larger set of very-high-energy (VHE) gamma-ray sources, allowing a detailed derivation of the infrared region of the EBL. After selection cuts, a refined dataset of several hundred blazars up to z ~ 1, nearly five times larger than in our previous study, leads to a twofold enhancement in redshift binning resolution. This improvement, along with updated EBL results based on Fermi-LAT data to be presented in a separate contribution, allows for the reconstruction of the EBL evolution up to z ~ 4, providing a more detailed picture of its build-up over cosmic time with better resolution and reduced model dependence. Our results indicate that the EBL is well accounted for by resolved galaxy populations, leaving little room for additional diffuse contributions.

Speaker: Joshua Baxter

14:35 (Remote) Tracing the Evolution of the Extragalactic Background Light with 15 Years of Fermi-LAT Observations

The extragalactic background light (EBL) is a key observable for understanding galaxy evolution and cosmology, as it represents the cumulative radiation from all star-forming galaxies throughout cosmic history, spanning ultraviolet to far-infrared wavelengths, with an additional, less certain contribution from active galactic nuclei. High-energy gamma rays from distant blazars interact with the EBL via pair production, leading to an energy-dependent attenuation measurable with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. We present an updated measurement of the evolving EBL using the first 15 years of Fermi-LAT data, analyzing a sample of approximately 1500 blazars from the 4LAC catalog, reaching z ~ 4 and effectively doubling the source count from previous studies. Compared to the 12 redshift bins in our previous analysis based on 9 years of data, we now resolve EBL attenuation across 19 redshift bins with reduced uncertainties, refining our ability to trace its evolution back to a Universe age of only 1.5 billion years. These results enables us to probe the cosmic gamma-ray horizon, i.e. the energy at which the universe becomes opaque to gamma rays, and the EBL evolution with unprecedented accuracy. These findings provide the most detailed characterization of the EBL ever achieved with Fermi-LAT.

Speaker: Dr Justin Finke

13:20 → 14:50 GA: ground experiments

13:20 The current status of ALPACA

The Andes Large area PArticle detector for Cosmic ray physics and Astronomy (ALPACA) is a new air shower array experiment under construction in the Bolivian Andes at the altitude of 4740m. The aim of the experiment is to explore the southern gamma-ray sky beyond 100 TeV to reveal the yet unknown PeV cosmic-ray accelerators. The surface array consisting of 401 plastic scintillating counters covers 82,800m^2 and the underground muon detector array of 3600m^2 area enables the identification of electromagnetic showers from hadronic shower background. A prototype surface array named ALPAQUITA has been running since 2023 and the construction of the underground muon detector will start in 2025. In this presentation, the status of the ALPACA project is reviewed in addition to the initial performance of ALPAQUITA for the hadronic cosmic-ray observations.

Speaker: Takashi Sako (University of Tokyo (JP))

13:35 The Southern Wide-field Gamma-ray Observatory: A Next-generation Ground-based Survey Instrument for Gamma-ray Astronomy

A collaboration of scientists across the globe is currently working on the development of the Southern Wide-field Gamma-ray Observatory (SWGO), a next-generation gamma-ray facility to be constructed in Chile. SWGO will provide wide field-of-view coverage with a high duty cycle for a large portion of the southern sky and complement observations of existing ground-based survey instruments in the Northern Hemisphere and of the Cherenkov Telescope Array which is scheduled to begin science operation in the mid-twenties. Recent discoveries by HAWC and LHAASO such as TeV gamma-ray halos associated with pulsars, >30 TeV gamma-ray emission from binary systems, tens of PeVatron candidates, and multi-TeV gamma-ray emission from a GRB, underscore the need for SWGO in the Southern Hemisphere. In my talk, I will present science drivers of the project and the performance of its baseline design measured against these science benchmarks. I will show the project status and timeline, including progress made toward the construction of SWGO.

Speaker: Petra Huentemeyer

13:50 Finalizing the Design of the Southern Wide-field Gamma-ray Observatory

The Southern Wide-field Gamma-ray Observatory (SWGO) is a next-generation experiment and offers precise wide-field observations of the southern gamma-ray sky. SWGO will be located in Pamba la Bola, Chile, at an altitude of 4770 m, cover an area of 1 km² and complement CTA and LHAASO. By leveraging double-layered Water Cherenkov Detectors, the SWGO design will facilitate gamma-ray observations from 100s of GeV to the PeV scale.
This contribution will discuss recent advancements in optimizing the SWGO array layout and detector design. Furthermore, we present the preliminary Instrument Response Functions of the observatory, demonstrating the effectiveness of the SWGO approach.

Speaker: Dr Jonas Glombitza (Erlangen Centre of Astroparticle Physics)

14:05 A proposal for a multiPMT detector in the Southern Wide Field Gamma-Ray Observatory (SWGO)

The SWGO collaboration proposes constructing a wide-field-of-view observatory to explore the southern hemisphere sky in the 100 GeV - 1 PeV energy range. The selected site is the Atacama Astronomical Park in Chile. Currently, the HAWC and LHAASO experiments are the only ground-based arrays for gamma-ray detection operating in this energy range, and both are located in the northern hemisphere. The detector will be based on water Cherenkov detector units, with an inner array with a high fill factor (>60%) and a large (about 1 km^2 square) outer array with a much lower fill factor (<5%) to explore the highest energies. In this contribution, we describe one of the proposed photodetectors for the Cherenkov detector unit, the multiPMT, an enclosed waterproof vessel embedding seven 3'' photomultipliers with the electronics to control and acquire the photosensors signals. Each PMT is equipped with a high-voltage board plus a front-end board, and a main board manages the DAQ for all seven channels. Similar solutions have already been proven feasible and largely implemented in other experiments, such as Km3Net and HyperKamiokande. Among the many advantages of this device compared to a large area PMT are the increased dynamic range, a better timing resolution, and an intrinsic directional sensitivity. Simulations show these factors can improve event reconstruction and discrimination between gamma-ray-initiated showers and the hadronic background. A first multiPMT has been deployed in a prototype SWGO Cherenkov detector unit at CBPF in Rio de Janeiro, and the first data are presented here. Two additional prototypes are planned to be installed at the SWGO pathfinder.

Speaker: Luigi Lavitola (University Federico II and INFN, Naples (IT))

14:20 Prospects for Galactic Science with SWGO

The forthcoming Southern Wide-field Gamma-ray Observatory will be located in Chile and ideally situated to observe the southern Galactic Plane. With its continuous survey capabilities and large collection area at high energies ≥ 100 TeV, SWGO will significantly contribute to studies of galactic gamma-ray sources. In this contribution, we refine the galactic science case for SWGO in light of recent progress in gamma-ray astronomy as well as the site selection and design of the facility. We anticipate the discovery potential for SWGO in the Southern sky, particularly with regard to extended sources such as supernova remnants, pulsar wind nebulae and halos, stellar clusters and diffuse emission, as well as continuous monitoring and large-scale sky surveys suitable for e.g. binary systems and globular clusters.

Speaker: Alison Mitchell (ECAP, FAU Erlangen-Nürnberg)

14:35 Expected performances of the SWGO observatory to ultra high energy gamma-ray

The Southern Wide-field Gamma-ray Observatory (SWGO) will be a next generation ground array experiment probing the Southern sky in search of gamma-ray sources from the Galactic plane. The experiment will be located in the Atacama Astronomical Park at 4770 m above sea level. The observatory will be a wide field of view and high duty cycle (almost 100%) array measuring the Extensive Air Showers (EAS) generated by primaries of energy greater than 100 GeV. SWGO will rely on the Water Cherenkov Detector (WCD) technique to study the ground particle distribution of the secondary particles of the EAS, to reconstruct the characteristics of the primary gamma-rays. Recently, the HAWC and LHAASO experiments detected various sources at energies greater than 100 TeV, both arrays being in the Northern hemisphere, and there is a clear lack of an observatory exploring the Southern hemisphere sky at these energies. In this contribution, we describe the expected performance of the current reference configuration (nearly 1 km2 area with a dense core at the centre) of the SWGO observatory in the 30 TeV - 1 PeV energy range. The expected sensitivity of the array is comparable to the LHAASO one, the energy resolution is about 15% and the angular one is 0.1-0.15 degrees, showing an improvement with respect to current observatories.

Speaker: Andrea Chiavassa (Università degli Studi & INFN Torino)

13:20 → 14:50 NU: physics

13:20 Neutrino results at TeV-energies from the LHC-FASER experiment

The FASER experiment at the LHC aims to study neutrinos of all three flavors at TeV energies and search for new long-lived particles. The FASER detector, a 1-ton-scale emulsion-electronic hybrid neutrino detector, is located 480 m downstream of the ATLAS $p$-$p$ interaction point, directly in the line of sight. Data taking began with the start of LHC Run 3 in 2022, and a total of 190 fb$^{-1}$ of data has been collected. The first cross-section measurements of electron and muon neutrinos at around 1 TeV were reported in 2024. In this talk, we will present updated neutrino interaction rates, and interprettations in both neutrino cross section and hadron production at $\sqrt{s}=13.6$ TeV. We will also discuss the future neutrino program of FASER and the Forward Physics Facility at the LHC.

Speaker: Hiroki Rokujo (Nagoya University (JP))

13:35 Predictions of neutrino fluxes at the Forward Physics Facility at the high-luminosity LHC

High-energy collisions at the Large Hadron Collider (LHC) have traditionally focused on particle production at small pseudorapidities. However, to further utilize the valuable data from particles produced at the ATLAS interaction point along the beamline, the proposed Forward Physics Facility (FPF) aims to study particle production in the far-forward region at the high-luminosity LHC. The FPF will house a suite of experiments with the ability of enhancing hadronic interaction models by measurement of the resulting neutrino fluxes. These advancements are critical for astroparticle physics, linking forward scattering processes to extensive air showers and improving our understanding of cosmic-ray interactions. This work investigates simulated neutrino fluxes in the far-forward region from proton-proton collisions at ATLAS, analyzing final state particles propagated to this new facility. Results from this simulation provide theoretical expectations for the neutrino fluxes at the FPF, offering insights to refine hadronic interaction models, including the most recently developed, and better estimate atmospheric neutrino backgrounds in astrophysical neutrino telescopes.

Speaker: Dennis Soldin (University of Utah)

13:50 The quest for Lepton Flavour Violation and the neutrino nature: status of the LEGEND experiment

If neutrinos were the one (and only) instance of elementary particles of the Majorana type, they could undergo a hypothetical process violating lepton number, the so-called neutrino-less double-beta decay (0νββ). If 0νββ indeed were observed, that would be enough to claim the Majorana nature of neutrinos. This would have substantial repercussions on cosmology and provide a possible mechanism for the matter-antimatter imbalance in the universe.
Several experiments have been conceived which search for 0νββ in a handful of isotopes. A variety of experimental techniques are being employed in the quest. So far the best statistical sensitivity on the half-life for the 0νββ process is around 10^26 yr and belongs to experiments employing germanium both as a source and as a semi-conducting detector. This sensitivity is attained by combining the current analysis of data from the LEGEND-200 experiment and the legacy of its predecessors, the GERDA and MAJORANA Demonstrator experiments.
In this talk I will give an update on the “LEGEND” project: using a two-stage approach with about 200 kg first and then 1000 kg of germanium diodes enriched in the active isotope, 76Ge, LEGEND aims to attain a half-life sensitivity around 10^28 yr, thus probing the inverted-ordering of the neutrino masses. I will review the general concept and design of LEGEND-200 and describe the detector and its current results, from the first data taking periods of 2023 and 2024 at the Laboratori Nazionali del Gran Sasso in Italy. I will also illustrate how the backgrounds affect the sensitivity and in which way they are characterized and suppressed. Finally, I will provide an expected timeline to get LEGEND-1000 operational and the related R&D and procurement activities.

This work is supported by the U.S. DOE and the NSF, the LANL, ORNL and LBNL LDRD programs; the European ERC and Horizon programs; the German DFG, BMBF, and MPG; the Italian INFN; the Polish NCN and MNiSW; the Czech MEYS; the Slovak RDA; the Swiss SNF; the UK STFC; the Canadian NSERC and CFI; the LNGS and SURF facilities.

Speaker: Giuseppe Salamanna (Roma Tre University and INFN - Roma Tre)

14:05 Potential for atmospheric neutrino physics with JUNO

The Jiangmen Underground Neutrino Observatory (JUNO) is a next-generation neutrino experiment located in China, currently undergoing the Liquid Scintillator (LS) filling phase. With 20 ktons of ultra-pure LS, JUNO seeks to make world leading measurements of three neutrino oscillation parameters and determining the Neutrino Mass Ordering (NMO).
Even though it is designed to primarily use reactor neutrinos to this aim, JUNO will also be able to study neutrino oscillations using atmospheric neutrinos, which will provide a synergetic channel exploiting matter effects on neutrino oscillations. This talk will report the latest updates on the JUNO capabilities for atmospheric neutrino detection at GeV energies.

Speaker: marta colomer (ULB (IIHE))

14:20 Search for decoherence due to quantum gravity with the IceCube Neutrino Observatory

In order to develop a consistent quantum theory of gravity, we must understand whether spacetime exhibits fluctuations at the Planck scale. If these Planck-scale fluctuations exist, they may cause propagating particles to evolve in an apparently non-unitary manner. Neutrinos, which interact only via the weak force and gravity, maintain quantum coherence while propagating over large distances. Thus, neutrino oscillations serve as a precise interferometer to search for Planck-scale fluctuations of spacetime. The IceCube Neutrino Observatory is the world’s largest neutrino telescope, located in the Antarctic glacier. We search the data on atmospheric neutrinos detected by IceCube in the energy range 0.5-100 TeV to test for neutrino decoherence. In this contribution, we present the sensitivity of the analysis, which shows significant improvement compared to previous IceCube results as a result of improved reconstruction and a larger sample of events.

Speaker: Tanvi Krishnan (Harvard University)

14:35 (Remote) First Ultra High Energy Neutrino Search with a Hybrid Phased and Traditional Detector in the Askaryan Radio Array

The Askaryan Radio Array (ARA) is an in-ice ultra-high-energy (UHE, >10 PeV) neutrino experiment at the South Pole, designed to detect neutrino-induced radio emission in ice. It consists of five independent stations, each featuring a cubic lattice of in-ice antenna clusters spaced ~30 m apart and buried ~200 m below the surface. The fifth ARA station (A5) is unique due to its central phased array string, which employs an interferometric trigger to enhance sensitivity to weak signals otherwise buried in noise. This low-threshold trigger makes ARA the first in-ice radio neutrino experiment to demonstrate a significant improvement in detecting low signal-to-noise ratio (SNR) radio signals.

We present progress toward the first UHE neutrino search utilizing A5's hybrid detection capability, incorporating advancements in data selection and background rejection. This analysis is the first to fully apply dedicated event selection to both components of ARA's hybrid detector, improving directional reconstruction and significantly enhancing background rejection compared to previous analyses. This approach paves the way for next-generation in-ice UHE neutrino experiments.

Speaker: Paramita Dasgupta (CCAPP Fellow at the Ohio State University)

13:20 → 14:50 SH: neutron monitors

13:20 HLEA and THIMON: Strengthening Neutron Monitor Observations from Haleakalā

The installation of two new neutron monitors, HLEA and THIMON, at the summit of Haleakalā, Hawai‘i, marks a significant advancement in cosmic ray and solar neutron studies. Situated at 3,055 meters above sea level, these monitors benefit from minimal atmospheric interference, enabling high-precision measurements of galactic cosmic rays (GCRs) and solar neutron flux. Operational since December 2024, HLEA and THIMON address a critical geographical gap in the Pacific region, providing valuable data for space weather studies and cosmic ray research. Their strategic location allows for cross-comparisons with other neutron monitors, enhancing global network calibration and reliability.

This presentation will outline the technical specifications of HLEA and THIMON, their initial performance metrics, and early scientific insights. Additionally, we will discuss their integration of these stations, part of the Simpson Neutron Monitor network, into the neutron monitor database (NMDB) and their role in strengthening international collaboration. Their inclusion reinforces the necessity of investing in new stations and maintaining robust data infrastructures for long-term space weather monitoring.

Furthermore, we have established a Space Weather and Mission Control Center in Hawai‘i, which will remotely operate the neutron monitors while also serving as a hub for space weather alerts and critical space situational awareness information. This center will play a key role in student recruitment, providing a hands-on learning environment for STEM students and showcasing the importance of space weather studies to the next generation of scientists and engineers.

Speaker: Veronica Bindi (University of Hawai'i at Manoa (US))

13:35 Cosmic-Ray Spectral Variations during 2007-2025 with Neutron Monitor Time-Delay Measurements at High Cutoff Rigidity

The leader fraction, L, is defined as the fraction of neutron monitor counts that are not temporally associated with a later count in the same neutron monitor counter due to the same cosmic ray shower. L was extracted from time-delay histograms and serves as a precise indicator of spectral variations in cosmic rays above the cutoff rigidity. In this work, we analyze long-term variations in L measured by the Princess Sirindhorn Neutron Monitor (PSNM) at Doi Inthanon, Thailand, which has the highest vertical cutoff rigidity for a fixed neutron monitor station (16.7 GV). PSNM has recorded time-delay histograms since 2007, during which time the data acquisition system has continually been upgraded, necessitating normalizations to ensure the consistency of the long-term L dataset. We investigated the spectral variation of Galactic cosmic rays above ∼17 GV over two sunspot minimum and two sunspot maximum periods, including hysteresis effects. Furthermore, we compare L from PSNM with the daily proton spectral index derived from recently published Alpha Magnetic Spectrometer (AMS-02) data aboard the International Space Station, covering 2011–2019. This comparison provides the relationship between neutron monitor leader fraction variations and direct measurements of the proton spectral index at high rigidities.
This project is funded by National Research Council of Thailand (NRCT): N42A661044 and the National Science and Technology Development Agency (NSTDA) and National Research Council (NRCT): High-Potential Research Team Grant Program (N42A650868).

Speaker: Chanoknan Banglieng (Rajamangala University of Technology Thanyaburi, Pathum Thani)

13:50 Hourly measurements of cosmic-ray spectral variation during Forbush decreases using ground-based neutron and muon detectors

Solar storms can disturb Galactic cosmic-ray (GCR) fluxes within the heliosphere at short time scales in events known as Forbush decreases (FDs). We extract hourly GCR spectral variations during FDs from a global network of ground-based neutron monitors and muon detectors using two independent methods: A) fitting a GCR rigidity spectral model with anisotropy up to second order, and B) analyzing time delay distributions between successive neutron detections by each counter of the South Pole Neutron Monitor to obtain the “leader fraction”. Both methods provide consistent results for spectral index variations during five major FDs between 2015 to 2023 and agree very well with the daily space-based observations by AMS-02 when such data are available. This analysis demonstrates the precision level of ground-based spectral measurements and offers techniques for real-time space weather monitoring (publicly available at https://neutronm.bartol.udel.edu/realtime/southpole.html) for use in FD studies and space weather alerts. Partially supported by the National Science and Technology Development Agency (NSTDA) and National Research Council of Thailand (NRCT): High-Potential Research Team Grant Program (N42A650868).

Speaker: Warit Mitthumsiri (Department of Physics, Faculty of Science, Mahidol University)

14:05 Monte Carlo Simulations of Multiple-secondary Cosmic Ray Detection by Neutron Detectors in Mawson Station, Antarctica

Neutron monitors (NMs) are basic instruments to measure Galactic cosmic ray variations in the range of ~ 1 to 50 GeV. The upgraded electronics at a few NM stations enable the analysis of the relative time delays and relative positions of multiple secondary particles produced by the same primary particle in Earth’s atmosphere. In this work, we performed atmospheric Monte Carlo Simulations using FLUKA Then, we illuminated the simulated detector by using rectangular beams and recorded the counts produced by all secondaries from the same primary cosmic ray. We calculated the cross-counter multiplicity and cross-counter “leader fraction” for different counter separations, which helps provide more insight into atmospheric showers for cosmic rays in this energy range. We compared model results with real count rate and absolute timing data from the NM and bare neutron counters at Mawson Station. With this technique, we can distinguish the contributions of single secondaries and multiple secondaries to the cross-counter multiplicity. We gratefully acknowledge the logistical support provided by Australia’s Antarctic Program for operating the Mawson neutron monitor. This research was also supported by a Postgraduate Scholarship from the Mahidol University Faculty of Graduate Studies, by Thailand's Office of the Permanent Secretary, Ministry of Higher Education, Science, Research and Innovation (OPS MHESI, Grant No. RGNS 65-181), by Thailand's National Science and Technology Development Agency (NSTDA) and National Research Council of Thailand (NRCT) under the High-Potential Research Team Grant Program (N42A650868), and from the NSRF via the Program Management Unit for Human Resources & Institutional Development, Research and Innovation (B39G670013).

Speaker: Mehak kanwal

14:20 A Simulation Study of the Response of the Princess Sirindhorn Neutron Monitor and Bare Counters to Solar Neutrons

The Sun can occasionally accelerate particles to become solar energetic particles, some of which may collide with the Earth’s atmosphere and produce secondary air showers that ground-based neutron monitors can detect. This work investigates the Princess Sirindhorn Neutron Monitor (PSNM) response to solar neutrons originating from solar activity such as solar flares and coronal mass ejections. The PSNM, located at an altitude of 2560 m near the equator with a high geomagnetic cutoff rigidity of 16.7 GV, is particularly suited for this study as it can potentially detect lower-energy (sub-GeV) solar neutrons against a background of higher-energy charged cosmic rays because neutrons are not affected by the geomagnetic field. Furthermore, since the start of operations in 2007,PSNM has deployed bare counters without surrounding lead or polyethylene. These bare counters are more sensitive to low-energy atmospheric neutrons and may be used to distinguish showers from solar neutrons versus those from Galactic cosmic-ray ions. This research employs Monte Carlo simulations to model the interactions of solar neutrons with the Earth’s atmosphere and the response of PSNM to solar neutrons. We simulate neutron showers across a range of energies at different zenith angles. This study provides useful insights into the capabilities of neutron monitors, together with bare counters, for solar physics research and contributes to advancing our understanding of solar neutron detection. This research was supported by Thailand’s National Science and Technology Development Agency (NSTDA) and the National Research Council of Thailand (NRCT) under the High Potential Research Team Grant Program (N42A650868).

Speaker: Areej kazmi (Mahidol University, Thailand)

14:35 Response Functions of a Neutron Monitor from the 2023-24 Latitude Survey Aboard the Araon Icebreaker

A latitude survey using the Changvan neutron monitor, a ship-borne detector, was conducted aboard the South Korean Icebreaker "Araon" in 2023–24, spanning from Antarctic and Arctic regions to study cosmic ray modulation. The monitor features a 3NM64-like configuration with three proportional counters: a leaded BF₃ tube from LND Inc. at one edge, an unleaded BP28 tube in the middle, and a leaded BP28 tube at the other edge. Unlike standard models, the absence of lead rings around the middle tube classifies it as a semi-leaded neutron monitor. This study presents observed detector response functions, with geomagnetic cutoff rigidity along the voyage calculated using the IGRF-14 model. The results provide insights into the performance of these proportional counters under varying geomagnetic conditions, and a comparison of results from successive years will allow precise measurement of the rigidity dependence of solar modulation. Partially supported by the National Science and Technology Development Agency (NSTDA) and National Research Council (NRCT): High-Potential Research Team Grant Program (N42A650868).

Speaker: Prof. Waraporn Nuntiyakul (Chiang Mai University (TH))

14:50 → 15:20 Coffee

15:20 → 16:50 CRD: experimental results: primary CR

15:20 Update of the Helium flux measurement with CALET on the International Space Station

The CALorimetric Electron Telescope (CALET) is a space-based calorimetric
instrument, designed to carry out precise measurements of high energy cosmic rays. Installed on the Japanese Experiment Module – Exposed Facility on the ISS, it is collecting data with excellent performance and no significant interruptions since October 2015. We present the updated results of the direct measurement of the energy spectrum of cosmic-ray helium, based on more than 9 years of collected data, with an expected statistical increase of about 40% compared with the previously published measurement. The helium flux shows significant deviations from a single power law with a progressive hardening around a few hundred GeV followed by a softening in the multi-TeV region. Moreover, a different analysis procedure, based on machine learning approach, has been developed to improve the event selection efficiency at the highest energies. The increase in statistics, combined with the more sophisticated analysis procedure, allows to extend the upper limit of the measured energy range and to improve the precision of the measurement itself in the high energy part of the spectrum.

Speaker: Paolo Brogi (Universita degli studi di Siena (IT))

15:35 Properties of Primary Cosmic Ray Nuclei: Thirteen-year Results from the Alpha Magnetic Spectrometer

We report the latest results of primary cosmic ray proton, helium, carbon, oxygen, neon, magnesium, silicon, sulfur, and iron fluxes based on the data collected by the Alpha Magnetic Spectrometer experiment on the International Space Station during 13.5 years of operation. The unique properties of primary cosmic rays will be discussed.

Speaker: Jose Ocampo Peleteiro (Universita e INFN, Bologna (IT))

15:50 Latest Advancements on Cosmic Ray Carbon and Oxygen with the DAMPE Space Mission

The Dark Matter Particle Explorer (DAMPE), is a space–borne detector designed for precise Galactic Cosmic Ray (GCR) studies in a wide energy range (up to a few hundreds of TeV), along with detailed measurements of high–energy gamma–rays and indirect searches of Dark Matter (DM). The satellite was successfully launched into a sun–synchronous orbit at 500 km, on December 17th 2015 and has been successfully taking data ever since.

DAMPE can provide valuable insights on the energy spectra of medium mass nuclei (CNO group) with exceptional resolution. In this work, the latest advancements regarding the spectral measurement of carbon and oxygen nuclei, will be presented, along with additional insights on the C/O flux ratio and the collective CNO flux, with 9 years of DAMPE flight data. Said results are crucial in deciphering distinct features across all spectra, complimented by a significant extension into the multi-TeV/n region, with great accuracy.

Speaker: Dimitrios Kyratzis (Gran Sasso Science Institute (IT))

16:05 Energy spectra and flux ratios of BCNO cosmic-ray nuclei measured by CALET up to multi-TeV energies

We present the measurement of the individual energy spectra for boron, carbon, nitrogen and oxygen cosmic rays based on data collected by the CALorimetric Electron Telescope (CALET) during more than 9 years of operation on the International Space Station. These spectra are measured in the energy range from 10 GeV/n to several TeV/n using a fully calorimetric instrument, 1.3 nuclear interaction lengths thick, equipped with charge detectors providing single element resolution. The B, C and O spectra have been updated from our previously published results with more statistics and refined systematic uncertainty estimates, while the N energy spectrum is a new preliminary measurement. We also present the energy dependence of the B/C, B/O and N/O flux ratios, interpreting these results with fitting models including a spectral break in the power law of the diffusion coefficient and a constant residual propagation path length. Finally, we show the combined CNO flux up to hundreds of TeV in particle energy.

Speaker: Prof. Paolo Maestro (Universita degli studi di Siena (IT))

16:20 Direct measurement of cosmic neon, magnesium, and silicon fluxes with DAMPE

The Dark Matter Particle Explorer (DAMPE) is a satellite-based detector optimized for precise Galactic cosmic ray studies up to hundreds of TeV. Since its launch on December 17th, 2015, DAMPE has been continuously collecting data on high-energy cosmic particles with excellent statistics and particle identification capabilities, thanks to a large geometric factor and a very good energy resolution. In this contribution, the latest advancements concerning the direct measurement of the energy spectra of cosmic-ray neon, magnesium, and silicon nuclei obtained by DAMPE will be presented. Precise knowledge of these spectral measurements could provide valuable insights into the origin, acceleration, and propagation processes of cosmic rays in the Galaxy.

Speaker: Elisabetta Casilli (University of Salento and INFN Lecce)

16:35 Properties of Cl and K Cosmic Nuclei: Results from the Alpha Magnetic Spectrometer

We report the latest results on the properties of Cl and K cosmic rays fluxes in the rigidity range 2.5 GV to 1.3 TV based on 0.14 million Cl and 0.17 million K nuclei collected by the AMS. We observe that fluxes are well described by the sums of a primary cosmic ray component and a secondary cosmic ray component. With our measurements, the abundance ratios at the source Cl/Si and K/Si are determined independent of cosmic ray propagation.

Speaker: Yao Chen (Shandong Institute of Advanced Technology (CN))

15:20 → 16:50 CRI: anisotropy

15:20 Evolution of cosmic ray anisotropy with energy up to PeV observed by LHAASO-KM2A

The evolution of cosmic ray large-scale anisotropy (LSA) with energy is essential for studying the origins of LSA, which are closely related to the origins and propagation of cosmic rays. However, due to both the low flux of cosmic rays and inconsistency among experiments, the observations of LSA above one hundred TeV are subject to large uncertainties. We utilize over three years data from the kilometer square array (KM2A) of LHAASO to observe the LSA. The measurements covered a wide energy range, reaching PeV, with high precision.

Speaker: Wei Gao (IHEP,CAS)

15:35 The anisotropy of cosmic ray light and heavy components observed by LHAASO-KM2A

The anisotropy in different mass components of cosmic rays can provide stringent constraints on theoretical models regarding the origin of anisotropy, such as the distribution of sources, the propagation of cosmic rays, and the local magnetic field environment. This is particularly significant in the high-energy range, from hundreds of TeV to PeV, where the anisotropy exhibits considerable variation. However, to date, the cosmic-ray anisotropy of different mass compositions in this high energy range are not reported. The muon measurements from the LHAASO-KM2A offer an opportunity to identify the components of cosmic rays. In this study, we utilize three years of data from KM2A to measure the anisotropies of different mass composition ratios across tens of TeV to PeV range. We obtained high-purity samples of light and heavy component cosmic rays, and our findings indicate that the anisotropies show variations for lighter components at lower energies.

Speaker: Prof. Huihai He (Institute of High Energy Physics, CAS)

15:50 All-Sky Cosmic-Ray Anisotropy Update at Multiple Energies

We present preliminary results on an updated full-sky analysis of the cosmic-ray arrival direction distribution with data collected by the High-Altitude Water Cherenkov (HAWC) Observatory and IceCube Neutrino Observatory with complementary field of views covering a large fraction of the sky. This study extends the energy range to higher energies. The HAWC Observatory, located at 19°N has analyzed 8 years of cosmic-ray data over an energy range between 3.0 TeV and 1.0 PeV and confirms an energy-dependent anisotropy in the arrival direction distribution of cosmic rays seen by other experiments. Combined with recently published results from IceCube with 12 years of data, the combined sky maps with 93% coverage of the sky —between 70°N and 90°S— and the corresponding angular power spectra largely eliminate biases that result from partial sky coverage.

Speaker: Dr Juan Carlos Diaz-Velez (University of Wisconsin-Madison)

16:05 Observation of large-scale anisotropy of very high-energy cosmic-ray protons with LHAASO-KM2A

We present a measurement for large-scale anisotropy of pure protons with the Large High Altitude Air Shower Observatory. We analyze the data collected from the full array of KM2A in three years' operation. We selected the proton data set using a cut on the muonic and electron magnetic components ratio, similar to the gamma/background discrimination technique in KM2A. The purity of the proton sample is up to 80%, and the reconstructed energy is from 10 TeV to 220 TeV. We first perform the energy evolution analysis of the dipole anisotropy of protons at this energy.

Speaker: Jiayin He

16:20 Latest findings on large-scale cosmic ray anisotropy from the GRAPES-3 experiment

Cosmic ray anisotropy at various scales has been observed over the past decade by multiple experiments in both the Northern and Southern Hemispheres. The GRAPES-3 experiment, located at 11.4 degrees North, is well positioned to study a significant portion of both hemispheres, covering nearly 70 percent of the sky at TeV energies. Observing large-scale anisotropy is particularly challenging since the effect is extremely small, measuring less than 0.1%, while detector and atmospheric influences can reach up to 5% and must be carefully mitigated. Using four years of data collected by GRAPES-3 between January 1, 2013, and December 31, 2016, we apply the iterative maximum likelihood method to extract the large-scale anisotropy. The detection significance exceeds 10 standard deviations. The results, along with a comparison to findings from other experiments, will be presented at the conference.

Speaker: Dr Medha Chakraborty

16:35 Observation of medium-scale anisotropy of very high-energy cosmic rays with LHAASO-KM2A

The intensity of Galactic cosmic rays in the arrival directions is highly isotropic, however, many cosmic ray experiments have observed weak anisotropies of various angular sizes. In this work, we report the observation of the medium-scale structures with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO-KM2A). We have found that the positions of the excess regions, located at $\alpha\sim320^{\circ}, \delta\sim30^{\circ}$ (around 17 TeV), and $\alpha\sim120^{\circ}, \delta\sim40^{\circ}$, provide compelling evidence of energy dependence within the energy range of 10 TeV to over 100 TeV. Furthermore, the evolution behaviors of energy dependence may indicate that local complex turbulent environments play a potential role in the propagation of cosmic rays, which offers a new perspective on their origin and transport of cosmic rays.

Speaker: Dr Shiping Zhao (Purple Mountain Observatory)

15:20 → 16:50 GA: ground experiments

15:20 ASTRI-1: Early Data and Performance Highlights

The ASTRI Project is an international collaborative effort led by the Italian National Institute for Astrophysics (INAF) to develop, build, and operate a facility consisting of nine four-meter class Imaging Atmospheric Cherenkov Telescopes dedicated to gamma-ray astronomy in the 1–200 TeV range. The ASTRI Mini-Array is currently being installed in Tenerife at the Observatorio del Teide, and the first telescope, named ASTRI-1, is now fully operational.
The commissioning phase of ASTRI-1 began in November 2024, and the telescope has been regularly collecting data from the Crab Nebula, the standard candle of very high-energy gamma-ray astronomy.
The overall data sample consists of approximately 100 hours of observations at low zenith angles (<30°) and 50 hours at higher zenith angles, collected between November 2024 and early 2025, under varying night sky illumination conditions (dark and moonlight). The Crab Nebula was observed in wobble mode, with equal amounts of data divided into four symmetrical positions with same offset from the center of the camera. In order to assess the off-axis performance, different wobble offsets ranging from 0.5° to 4.5° were adopted.
In this contribution we present the performance of the telescope evaluated on the basis of data collected during the commissioning phase. We also report on the first scientific highlights achieved, with a focus on the analysis of the Crab Nebula, which provides key insights into the telescope sensitivity and performance. These preliminary results provide a strong foundation for future studies and pave the way for the next steps in the development of the ASTRI Mini-Array.

Speaker: Silvia Crestan

15:35 Status of the ASTRI Mini-Array Gamma-Ray Experiment

The ASTRI Mini–Array is an international project led by INAF to install and operate nine innovative Imaging Atmospheric Cherenkov Telescopes (IACTs) at the Observatorio del Teide site e, resulting from a hosting agreement between INAF and IAC. The facility will operate for at least 8 years. It will deeply observe the Galactic and extra-galactic sky at TeV energies to study compelling open questions of high energy astrophysics, e.g., the nature of pevatrons that accelerate the hadronic cosmic rays. The complete array will be ready to conduct the commissioning and scientific calibration activities by mid-2026. Compared to currently operating IACT systems (HESS, VERITAS, and MAGIC), the ASTRI Mini–Array will extend the sensitivity to 100 TeV and beyond, an almost never-explored energy range by IACTs. Therefore, ASTRI and the upcoming LACT array in China will complement the HAWC and LHAASO astroparticle experiments in the northern hemisphere and the CTAO northern observatory, which will operate at lower energies. This contribution overviews the ASTRI Mini–Array project’s design, technologies, and scientific goals. It will also present the results achieved from calibration and scientific data from the telescopes already installed and equipped with the advanced ASTRI Cherenkov camera.

Speaker: Dr Giovanni Pareschi (INAF - Osservatorio Astronomico di Brera)

15:50 New time-based parameters to enhance gamma-ray and hadron discrimination for the ASTRI Mini-Array event reconstruction

The ASTRI Mini-Array is an international project to build and operate an array of nine 4-m diameter Imaging Atmospheric Cherenkov Telescopes (IACT) at the Observatorio del Teide (Tenerife, Spain). The array has been designed to perform deep galactic and extragalactic gamma-ray sky observations in the 1-200 TeV energy range. As of today, the first telescope ASTRI-1 is fully operative, and in its commissioning phase.
In the effort of improving the sensitivity of the array, particularly in discriminating between gamma-ray- and hadron-induced showers, we are investigating whether the temporal evolution of the shower images, as recorded by the pixel time tag, can provide additional discriminatory power beyond the traditional morphological parameters. We have developed and tested a set of parameters and through extensive testing, we have identified a subset of them that exhibit good discriminatory efficacy. Combining these time parameters with the standard morphological parameters has demonstrated, in our preliminary analysis, a significant improvement in hadron rejection, especially at the lower end of the energy detection range, and a definite boost in the single telescope performance.
Here we show how this new set of parameters impacts on the analysis of the ASTRI-1 data taken in the November 2024 – February 2025 campaign and on its sensitivity.

Speaker: Valentina La Parola (INAF -IASF Palermo)

16:05 The Large Array of Imaging Atmospheric Cherenkov Telescopes (LACT): Performance and Status

The Large High Altitude Air Shower Observatory (LHAASO) has recently detected over 40 ultra-high-energy (UHE) gamma-ray sources. However, many of these sources are extended, and some are located within a small angular region (~1°) that LHAASO cannot resolve clearly. To address these limitations, the Large Array of Imaging Atmospheric Cherenkov Telescopes (LACT) has been proposed and is currently under construction at the LHAASO site, LACT consists of 32 telescopes, each with a field of view (FOV) of 8° . It has an angular resolution better than 0.05° and a large detection area of approximately 2 km² for energies above 10 TeV. Additionally, by integrating parameters from both the showers detected by LHAASO and the Cherenkov images captured by LACT, the array achieves robust gamma/hadron separation capabilities. This enables precise measurements of the energy spectra and morphologies of UHE gamma-ray sources. These capabilities are crucial for resolving the acceleration mechanisms and the origins of cosmic rays. In this presentation, we introduce the design and performance of LACT, discuss the prospects for studying UHE gamma-ray sources, and provide an update on the current status of the experiment.

Speaker: Dr Jiali Liu (The Institute of High Energy Physics, Chinese Academy of Sciences.)

16:20 Performance of LACT Array: Instrument Response Functions and Source Prospects

Large Array of imaging atmospheric Cherenkov Telescope (LACT) is an array of 32 Cherenkov telescopes with 6-meter diameter mirrors to be constructed at the LHAASO site, aiming to enhance our understanding of ultra-high energy gamma ray astronomy. This work presents a detailed performance assessment of the LACT array, focusing on the IRFs for both an 8-telescope subarray configuration optimized for large zenith angle observations (60°) and the full 32-telescope array, with a particular emphasis on a 20° zenith angle configuration for lower energy threshold observations.

We have generated IRFs using extensive Monte Carlo simulations of gamma-ray showers and the detector response. The IRFs include the effective area, angular resolution, and energy resolution as a function of reconstructed energy and offset angle. Crucially, these IRFs are produced in the standard Data format for Gamma ray astronomy (GADF), ensuring interoperability with existing analysis tools like Gammapy and ctools and enabling seamless integration into scientific workflows.

In this work, we also have used these GADF-format IRFs to simulate observations of key astrophysical sources and assess the LACT array's capabilities for morphology studies and spectral analysis.

Speaker: zhipeng zhang (University of Science and Technology of Chinaπ)

16:35 The SST-1M stereoscopic system

The Single-Mirror Small-Size Telescope (SST-1M) is an Imaging Atmospheric Cherenkov Telescope designed for detecting very high-energy gamma rays. With a compact design achieved through the adoption of silicon-photomultiplier pixels and a lightweight structure, SST-1M offers a large field of view of about 9° and features a mirror system of 4 m diameter with a PSF (at 80% of photon inclusion) of 0.08° on axis and 0.21° at 4° off-axis, and a fully digitizing readout almost deadtime free up to few kHz. The SST-1M achieved a high-performance and cost-effective solution for implementing an array of small-sized telescopes.
The stereoscopic system of two SST-1Ms is temporarily installed at the Ondrejov Observatory in the Czech Republic. From an altitude of only about 500 m and in harsh meteorological conditions, the system is detecting galactic sources and flares of AGNs. The accurate calibration of the detector and the simulation benchmark are ongoing. The results of its performance will be shown. A future final location is being considered and a future performance outlook will be discussed.

Speaker: Prof. Teresa Montaruli (Universite de Geneve (CH))

15:20 → 16:20 GA: magnetic fields

15:20 Constraints on the InterGalactic Magnetic Field using detected very-high-energy GRBs by the Cherenkov Telescope Array Observatory

The InterGalactic Magnetic Field (IGMF) is believed to be a remnant of the Big Bang and the origin of cosmological magnetic fields. However, it has yet to be detected. The Cherenkov Telescope Array Observatory (CTAO) will have the potential to place stricter constraints on the IGMF by analysing data from AGN and GRBs. In this study, we propose to simulate realistic observations in CTAO of GRBs detected so far in the TeV range, using the available instrument response functions of the Alpha configuration of CTAO: $4$ Large-Sized Telescopes (LSTs), $9$ Medium-Sized Telescopes (MSTs) in the CTAO-North array, and $14$ MSTs, $37$ Small-Sized Telescopes (SSTs) in the CTAO-South array. The expected IGMF signatures are modelled with a dedicated simulation code and the analysis of the synthetic data is performed using a joint, spectral and temporal fit. By assuming a power-law behaviour in energy with an unknown cut-off, we will extrapolate the detected GRBs into the tens of TeV energy range, we show that CTAO can constrain the IGMF in the range $\left[10^{-19},10^{-15}\right]\mathrm{G}$ for various coherence lengths and place limits on fields stronger than $10^{-15}\;\mathrm{G}$.

Speaker: Ténéman Keita (CEA Paris-Saclay)

15:35 Impact of GRB Physics on Pair Echoes and Intergalactic Magnetic Field Constraints

The origin of magnetic fields on cosmological scales remains one of the longstanding problems in cosmology. Magnetic fields observed in galaxies and clusters are typically explained through the amplification of weak seed fields. However, the nature of these weak seed fields remains largely unknown. Two scenarios are usually considered: the cosmological and the astrophysical scenarios.
To distinguish between these formation scenarios, it is crucial to search for signatures of magnetization in cosmic voids, which are regions devoid of large-scale structures. In this context, gamma-ray observations of extragalactic sources offer a powerful tool to measure or constrain the Intergalactic Magnetic Field (IGMF). Very High Energy (VHE) photons (E > 100 GeV) cannot propagate over large distances because they interact with the Extragalactic Background Light (EBL) via γγ pair production. The resulting electron-positron pairs then inverse Compton (IC) scatter photons from the Cosmic Microwave Background (CMB) up to γ-ray energies, initiating an electromagnetic cascade.
If a non-negligible IGMF is present, it deflects the pairs, leading to the so-called pair-echo emission in the case of Gamma-Ray Bursts (GRBs) emitting VHE photons. The characteristics of the pair-echo emission—such as its duration, time extension, and temporal profile—depend on the IGMF, providing a powerful tool to measure or constrain it.

In this contribution, we simulate afterglow emission for GRBs with different physical properties and investigate the possibility of detection of pair-echo emission in the GeV and tens of GeV bands. Specifically, we simulate the pair-echo emission from GRBs located up to redshift 1 for different IGMF configurations. We explore the IGMF strengths for which the pair-echo emission can dominate or compete with the afterglow, as a function of key GRB features such as jet opening angle, distance, and energetics. Our findings provide important predictions for the detection of pair echoes with current and upcoming gamma-ray observatories.

Speaker: Paolo Da Vela (INAF OAS Bologna)

15:50 Impact of Plasma Instabilities and of the Intergalactic Magnetic Field on Blazar-Induced Electromagnetic Cascades

Intergalactic weak magnetic fields can have non-negligible effects on the electromagnetic cascades induced by blazar gamma-ray emission. Secondary electrons and positrons are produced by primary gamma rays of energies ~TeV and can be magnetically deflected out of the line of sight to the source. However, these leptons can perturb the background intergalactic medium (IGM), resulting in the growth of plasma instabilities, which can also influence the electromagnetic cascade. The resulting gamma-ray spectrum, observable in the GeV-TeV energy range, can bear imprints of these two competing phenomena: deflection by the intergalactic magnetic field and plasma instability cooling. We present the results of numerical simulations that incorporate the combined impact of these two processes on the propagated gamma-ray spectrum of the blazar 1ES 0229+200.

Speaker: Suman Dey (II. Institut für Theoretische Physik, Universität Hamburg)

16:05 MeV cosmic-ray electrons modify the TeV pair-beam plasma instability

Relativistic pair beams created in the intergalactic medium (IGM) by TeV gamma rays from blazars are expected to produce a detectable GeV-scale electromagnetic cascade, but the cascade component is absent in the spectra of many hard-spectrum TeV-emitting blazars. One common explanation is that weak intergalactic magnetic fields deflect the electron-positron pairs away from our line of sight. An alternative possibility is that electrostatic beam-plasma instabilities drain the energy of these pairs before a cascade can develop. Recent studies have shown that beam scattering by oblique electrostatic modes leads to minimal energy loss. But these modes might be suppressed by linear Landau damping (LLD) due to MeV-scale cosmic-ray electrons in the IGM. In this work, we explore the impact of LLD on the energy-loss efficiency of plasma instabilities in pair beams associated with 1ES 0229+200.
We find that LLD effectively suppresses oblique electrostatic modes, while quasi-parallel ones continue to grow. In this way LLD enhances the energy-loss efficiency of the instability by more than an order of magnitude, depending on the distance from the blazar. We plan to follow up with a quantitative analysis of how this increased efficiency influences the observable spectra of the GeV cascade.

Speaker: Martin Pohl

15:20 → 16:21 NU: physics

15:20 Exploring Exotic and Non-Standard Phenomena in the NOvA Experiment Absrtac

The NOvA experiment, primarily focused on neutrino oscillation studies, also provides a unique platform to search for exotic and non-standard physics phenomena. In this talk, we present the ongoing analyses, outline the current status, highlight the methods and techniques, and discuss the preliminary results. We also highlight the importance of these searches for our scientific knowledge.

Speaker: Oleg Samoylov (Joint Institute for Nuclear Research (RU))

15:35 Exploring New Oscillation Scales with Galactic Neutrinos

The IceCube Neutrino Observatory recently published evidence for diffuse neutrino emission from the Galactic Plane at $4.5\sigma$ significance. This new source of astrophysical neutrinos provides an exciting laboratory for probing the nature of neutrino masses. In particular, extremely small mass splittings, such as those predicted by quasi-Dirac neutrino mass models, and finite neutrino lifetimes from neutrino decays, would induce effects on the spectra and flavor ratios of neutrinos with TeV-scale energies traversing kiloparsec-scale baselines. Using TANDEM, a new three dimensional galactic neutrino emission model, we explore the sensitivity of IceCube and KM3NeT/ARCA to these ultra-long baseline phenomena. We find that a combined analysis would be sensitive to as-yet unexplored regions of parameter space in both quasi-Dirac and decay scenarios; the sensitive region to quasi-Dirac parameter space is $10^{-15}~\mathrm{eV^2} \lesssim \delta m^2 \lesssim 10^{-10}~\mathrm{eV^2}$, and the sensitive region to invisible neutrino decay is $m / \tau \gtrsim 10^{-15.5}~\mathrm{eV^2}$. Our results demonstrate the potential that astrophysical neutrino sources and global neutrino telescope networks have in probing new regions of exotic neutrino mass models.

Speaker: Miller MacDonald (Harvard University)

15:50 Neutrino constraints on inelastic dark matter captured in the Sun

We study the possibility for large volume underground neutrino experiments
to detect the neutrino flux from captured inelastic dark matter in the Sun.
The neutrino spectrum has two components: a mono-energetic "spike" from
pion and kaon decays at rest and a broad-spectrum "shoulder" from prompt
primary meson decays. We focus on detecting the shoulder neutrinos
from annihilation of hadrophilic inelastic dark matter with masses in the
range 4-100 GeV. We find the region of parameter space that these
neutrino experiments are more sensitive to than the direct-detection
experiments. For dark matter annihilation to heavy-quarks, the projected
sensitivity of DUNE is weaker than current (future) Super (Hyper) Kamiokande
experiments, while for the light-quark channel, only the spike is
observable and DUNE will be the most sensitive experiment.

Speaker: Ina Sarcevic (University of Arizona)

16:05 Constraints on Neutrino Secret Interactions from Multi-messenger neutrinos scattering on CνB

We present new constraints on neutrino secret interactions (νSI) using high-energy and ultra high-energy astrophysical neutrinos as probes of new physics beyond the Standard Model. By studying neutrinos from established sources, such as SN1987A, NGC 1068, TXS 0506+056, PKS 0735+178, and the extreme-energy KM3-230213A event, we explore the potential interactions of Dirac neutrinos with a massive spin-one boson during their propagation through the Cosmic Neutrino Background (CνB). Notably, the KM3-230213A event allows us to probe an entirely new scale of interaction strength and reveals sensitivity to heavier mediator masses previously beyond reach.

Our analysis covers both ultra-relativistic and non-relativistic regimes, deriving exclusion limits on the νSI coupling constant across the full mediator mass range. We examine flavor-universal and flavor-non-universal coupling scenarios, the latter are often addressed in discussions about cosmological tensions such as H₀ and S₈ discrepancies. This work contributes to the ongoing development of the theoretical framework for νSI and illustrates the potential of multi-messenger neutrino observations to probe fundamental aspects of neutrino interactions.

Speaker: Maria Petropavlova

15:20 → 16:36 SH: Instrumentation

15:20 Observation of the Moon and Sun Shadows with the ALPAQUITA Air Shower Array in Bolivia

The ALPACA experiment, which consists of the large air shower array (83,000 m^2) and the water-Cherenkov-type muon detector (3,600 m^2), is a new project to observe cosmic rays and gamma rays in the energy range between TeV and PeV in the southern hemisphere. The prototype air shower array, named ALPAQUITA (18,000 m^2), has been fully operated at the Chacaltaya plateau (4,740 m a.s.l.) in Bolivia since April 2023. The ALPAQUITA array consists of 97 scintillation detectors with an area of 1 m^2, deployed with 15 m spacing.
The Moon and Sun block cosmic rays, and cast cosmic-ray shadows on Earth, so-called the Moon and Sun shadows. The geomagnetic and solar magnetic fields affect the trajectory of cosmic rays so that the position and depth of the shadow vary depending on cosmic-ray energy and time. These cosmic-ray shadows are utilized to evaluate the angular resolution, the pointing accuracy, and the absolute energy scale of the cosmic-ray instruments as well as the investigation of the time-dependent solar magnetic fields. In this work, we will evaluate the performance of the ALPAQUITA air shower array by the observed Moon shadow. We will also report on the Sun shadows observed around the solar maximum phase in solar cycle 25, compared with the Moon shadow.

Speaker: Dr Kazumasa Kawata (Institute for Cosmic Ray Research, University of Tokyo (Japan))

15:35 Design, Assessment, and Calibration of the Moon-Aiming Thai-Chinese Hodoscope for Observing Cosmic Ray Electrons, Solar Energetic Particles, and Lunar Albedo Ions

The Moon-Aiming Thai-Chinese Hodoscope (MATCH) is designed as a space weather payload for the Chang’E-7 lunar orbiter, aimed at enhancing space weather monitoring in the Earth-Moon region and measuring lunar albedo ions up to approximately 100 MeV/n. Additionally, it will provide continuous measurements of cosmic ray electrons up to around 120 MeV/n, thereby clarifying the contributions from Jovian and Galactic sources. Furthermore, Jovian electrons, together with solar energetic particles (SEPs) to a certain degree, constitute particles from a recognized source that can be utilized to investigate the effects of Earth's magnetotail during a segment of the Moon's orbit around Earth. The engineering challenges for Thailand’s nascent space program include integrated sensor design and fabrication, mechanical design, readout electronics with high resolution and sensitivity yet low power consumption and ensuring seamless integration with and safe operation of the Chang’E-7 orbiter spacecraft itself. This presentation will include the scientific objectives and technical design of the payload, validation via GEANT4 simulations of geometrical acceptance and angular resolution, along with the results from the detector payload’s calibrations using standard radiation testing in a space environment control chamber. The expected detection range will also be confirmed.

Speaker: Dr Kunlanan Puprasit (Mahidol University, Bangkok, Thailand and Chulabhorn Royal Academy, Bangkok, Thailand)

15:50 Comprehensive Study of the Lunar Energetic Particle Environment with LunPAN

LunPAN (Lunar Particle Analyzer Network) is a three-year mission proposal designed to comprehensively map the particle spectra in the lunar radiation field. It aims to provide precise measurements of Galactic Cosmic Rays (GCR), Solar Energetic Particles (SEP), and albedo particles, including charged particles, neutrons, and gamma-rays, originating from the Moon's surface. Therefore it will contribute to fundamental space physics, lunar geology sciences, space weather prediction, and radiation risk assessment for future lunar explorations. This is achieved through two state-of-the-art instruments; Pix.PAN and NeuPix. Pix.PAN is a compact magnetic spectrometer designed for precise measurements of penetrating charged particles, ranging from 100 MeV to 10 GeV. Based on the Mini.PAN project, Pix.PAN employs thin silicon pixel sensors optimized for energy resolution and particle identification. NeuPix is a hybrid active pixel sensor system capable of detecting neutrons, gamma-rays, and lower-energy charged particles between 10MeV and 100 MeV. Utilizing innovative sensor-converter combinations, NeuPix will provide spectral measurements of lunar albedo neutrons and gamma-ray fluxes. Currently, the LunPAN mission is accepted by ESA’s “Small Missions for Exploration – Destination the Moon” call for a pre-A phase study. We will discuss mission outline and expected scientific performance of the PixPAN and NeuPix.

Speaker: Dr Johannes Hulsman (Universite de Geneve (CH))

16:05 Technical design of the first Thai Space Consortium Satellite (TSC-1) and Its Polar Orbiting Ion Spectrometer Experiment (POISE) Payload

TSC-1 is the first Thai scientific research mission on a microsatellite, which has been designed and developed by the Thai Space Consortium. The satellite is planned to operate in Sun-synchronous Earth orbit at 500 - 600 km altitude and should be launch ready at the end of 2026. All design, construction, system integration, and testing are to be carried out in Thailand. The payloads include a Hyperspectral Imaging Camera and the Polar Orbiting Ion Spectrometer Experiment (POISE). The POISE detector is developed to characterize energetic ions for space weather monitoring. It uses the ΔE-E technique, comprising semiconductor detectors based on P-I-N junction parts designed and fabricated by Thai engineers and researchers, which in later versions will be combined with standard commercial parts (PIPs and silicon strip detectors) for benchmarking purposes. We will summarize the overall plan of TSC-1 and POISE, including the technical design, scientific concepts, geometrical acceptance, design of compact charge sensitive preamplifiers, and evaluation of the electronic dead-time of the data acquisition system. Radiation testing results for the engineering model prototype will also be presented.
This research was supported by the Office of National Higher Education, Science Research and Innovation Policy Council, organized by the Program Management Unit for Human Resources & Institutional Development, Research and Innovation (PMU-B), through the Hub of Talents in the TSC-1 satellite program, Grant (B11F670111). Partially supported by the National Science and Technology Development Agency (NSTDA) and National Research Council (NRCT): High-Potential Research Team Grant Program (N42A650868).

Speaker: Sunruthai Burom (National Astronomical Research Institute of Thailand, Chiang Mai, Thailand)

16:20 Advancing Solar and Heliospheric Studies with the CSES Programme

The China Seismo-Electromagnetic Satellite (CSES) program, a collaboration between the China National Space Administration (CNSA) and the Italian Space Agency (ASI), offers a new window into solar-terrestrial interactions through continuous monitoring of the near-Earth space environment. Since its launch in 2018, CSES-01 has provided valuable data on space weather phenomena, ionospheric dynamics, and the modulation of low-energy cosmic rays by solar activity. The upcoming launch of CSES-02 in 2025 will initiate multi-site observations, greatly enhancing our ability to disentangle temporal and spatial variations in the magnetosphere and heliosphere.
Operating in a Sun-synchronous orbit at ~500 km altitude, the CSES constellation will deliver simultaneous measurements of electromagnetic fields, plasma parameters, and energetic particle fluxes over a broad energy range (~100 keV to ~100 MeV). The Italian-led High-Energy Particle Detector (HEPD-02) aboard CSES-02 will significantly improve sensitivity to electrons, protons, and light nuclei, enabling precise studies of solar energetic particle (SEP) events, geomagnetic storms, and cosmic-ray transport in the heliosphere.
CSES-01 observations have already contributed to the understanding of solar modulation of low-energy cosmic rays, the response of the ionosphere to solar activity, and the evolution of geomagnetic disturbances. With its dual-satellite configuration, CSES-02 will enhance our capability to track SEP propagation, investigate Forbush decreases, and study variations in trapped and quasi-trapped particle populations. The improved revisit time of the constellation, reduced from five days to 2.5 days, will provide a more frequent sampling of space weather events and their impact on the near-Earth environment.
This contribution will highlight key results from CSES-01 relevant to heliospheric and magnetospheric physics and outline the expected advances enabled by CSES-02. The ability to perform multi-point, high-cadence observations will offer unprecedented insight into the coupling between solar activity, cosmic rays, and the Earth's magnetosphere, contributing to a deeper understanding of the dynamic processes governing near-Earth space.

Speaker: Roberto Iuppa (Universita degli Studi di Trento and INFN (IT))

15:21 → 16:51 CRI: miscellaneous

15:21 AugerPrime: Status and first results

With the knowledge and statistical precision derived from two decades of measurement, the Pierre Auger Observatory has significantly deepened our understanding of ultra-high-energy cosmic rays while unearthing an increasingly complex astrophysical landscape and exposing tensions with hadronic interaction models. The field now demands the mass of individual cosmic-ray primaries as an observable with an exposure that only the 3000-square-kilometer surface array of the Observatory can provide. Access to the primary mass hinges on the disentanglement of the electromagnetic and muonic components of extensive air showers. To achieve this, scintillator and radio detectors have been installed atop each existing water-Cherenkov detector of the surface array, whose dynamic range has also been enhanced through the installation of small-area PMTs. Additionally, the timing and signal resolution of all detector stations have been improved through upgraded station electronics, and underground muon counters have been installed in a region of the array with denser spacing. As the commissioning of the final components of AugerPrime reaches its conclusion and the enhanced array comes fully online, we present its performance and the first results from this now multi-hybrid observatory.

Speaker: David Schmidt

15:36 Monitoring and Performance of AugerPrime

The Pierre Auger Observatory upgrade, AugerPrime, is a multi-hybrid system designed to improve the sensitivity and precision of ultra-high-energy cosmic ray measurements. It includes scintillator detectors positioned both atop the enhanced Water-Cherenkov detectors and buried nearby for direct muon measurements, along with radio and fluorescence detectors. In this contribution, we present an overview of the monitoring tools developed for all AugerPrime components, focusing on real-time performance assessment and long-term stability metrics. By continuously tracking key parameters, we can identify potential issues early, enabling timely interventions and improving overall data quality. These strategies are crucial for maintaining the long-term reliability of the Observatory’s measurements and providing high-quality data for cosmic ray research in the coming decades.

Speaker: Belén Andrada (ITeDA)

15:51 Gamma/hadron discriminant variables in application to high-energy cosmic-ray air showers

Identification of primary cosmic rays on an event-by-event basis is a much-desired capability of cosmic-ray observatories. Several cosmic-ray air-shower experiments use so-called photon tags for gamma/hadron primary particle discrimination. These photon tag variables are derived from the total signals measured by an array of detectors and are correlated with the total number of muons in the air shower. In this work, variables based on time distribution of signals in detectors (trace-based discriminant variables) are studied and compared to total-signal-based variables. This study relies on simulated high-energy cosmic-ray air showers with energies around 10^17 eV. Since the variables discussed are derived from total signals and their time traces, which can be directly measured in real data, they are suitable for use as discriminant variables in the real ground-based cosmic ray experiments.

Speaker: Dr Nataliia Borodai (Institute of Nuclear Physics PAS, Krakow, Poland)

16:06 The First Observation of the Moon Shadow at an Average Energy of $7\times10^{17}\,$eV with the Pierre Auger Observatory

The interaction of cosmic rays with celestial bodies such as the Moon or the Sun produces a shadow in the arrival direction distribution of the cosmic rays reaching the Earth. Such deficits from an isotropic flux have been observed by astroparticle observatories below energies of $10^{15}\,$eV. Above this energy, measurements were limited due to the low number of events as a result of the steeply falling cosmic-ray flux with energy. With more than 10.6 million events recorded during 20 years of operation of the Pierre Auger Observatory, we report the first observation of the Moon shadow at an average energy of $7\times10^{17}\,$eV with a maximum significance above 3$\sigma$. Using this deficit, we verify the accuracy of the Observatory's absolute pointing. Additionally, we present the results of a similar study on the Sun's shadow and discuss both measurements in the context of the angular resolution of the Observatory.

Speaker: Katarína Simkova (Vrije Universiteit Brussel, Université Libre de Bruxelles)

16:21 Constraining the origin of the highest-energy cosmic-ray events detected by the Pierre Auger Observatory: a three-dimensional approach

Unveiling the sources of ultra-high energy cosmic rays remains one of the main challenges of high-energy astrophysics. Measurements of anisotropies in their arrival directions are key to identifying their sources, yet magnetic deflections obscure direct associations. In this work, we reconstruct the sky regions of origin of the highest-energy cosmic-ray events detected by the Pierre Auger Observatory by tracing their trajectories through Galactic magnetic fields using the most up-to-date models, while fully accounting for energy and directional uncertainties. A mixed composition at injection is assumed to model the detected charge distributions of such events. Different classes of astrophysical sources are investigated and tested for a correlation with the inferred regions of origin of the events. By incorporating constraints on the maximum propagation distances, we also allow for a three-dimensional localization of the possible source regions. Our findings provide new constraints on the sources of the highest-energy cosmic particles and offer fresh insights into the role of Galactic magnetic fields in shaping the observed ultra-high-energy cosmic-ray sky.

Speaker: Marta Bianciotto (INFN Torino)

16:36 Advanced techniques of searching for flares of ultra-high-energy photons from point sources

Astrophysical flares are one of the possible prominent source classes of ultra-high-energy (UHE, E > 10^17 eV) cosmic rays, which can be detected by recording clusters of extensive air showers in arrays of detectors. The search for sources of neutral particles offers distinct advantages over searching for sources of charged particles, as the former traverse cosmic distances undeflected by magnetic fields. While no cosmic-ray photons exceeding 10^17 eV have been definitively detected, identifying the clustering of events in cosmic-ray data would provide compelling evidence for their existence.
We compare two analysis methods for detecting direction-time clustering in ultra-high-energy extensive air showers: the standard approach, which examines multiplets, and the stacking method, which analyzes sets of doublets that are not necessarily consecutive, thus making it sensitive to multiple flares. Both techniques combine time-clustering algorithms with unbinned likelihood study. Background events (initiated by hadrons) can be more efficiently distinguished from photon-induced events (signals) by using a photon tag that employs probability distribution functions to classify each event as more likely to be initiated by either a photon or a hadron. We demonstrate that these methods can effectively distinguish between events initiated by photons and those initiated by hadrons (background), and can accurately reproduce both the number of photon events within flares and their duration. We calculate the discovery potentials, i.e., the number of events required to identify a photon flare. The methods discussed can be used to search for cosmic ray sources and/or improve limits on the fluxes of ultra-high-energy photons.

Speaker: Jaroslaw Stasielak (Institute of Nuclear Physics PAS, Krakow, Poland)

16:51 → 17:00 Break

17:00 → 17:05 Welcome by the Geneva Congress Office

17:05 → 18:35 Welcome Cocktail

Wednesday 16 July

08:15 → 09:00 Registration

09:00 → 10:30 Plenary session

09:00 Lighting up the sky: What gamma rays reveal About supernova remnant shocks

Gamma-ray observations over the past decade—from space-based instruments like Fermi-LAT to ground-based arrays such as H.E.S.S., MAGIC, and VERITAS—have provided an increasingly detailed view of supernova remnants (SNRs). Several dozens of SNRs have been detected in the GeV–TeV energy range, revealing a diverse population shaped by their environments and evolutionary stages, and new detections continue to expand the catalog of gamma-ray bright remnants. Observations by HAWC and LHAASO have even identified a few Galactic PeVatron candidates, though a direct connection to SNRs remains under investigation. Beyond remnants, gamma-ray detections from novae also underscore the ubiquity of shock-powered emission across explosive astrophysical systems. This presentation will highlight recent gamma-ray results offering fresh insight into the radiative signatures and energetic processes associated with supernova remnant shocks.

Speaker: Marianne LEMOINE

09:45 Multi-Messenger Signatures of the Milky Way Galaxy in Cosmic Rays, Neutrinos, and Gamma Rays

In this talk, I will review recent measurements of the local Galactic cosmic ray flux up to the knee region, as well as the emission from the Milky Way galaxy in gamma-rays and neutrinos within the same energy range. I will discuss the major classes of Galactic sources of high-energy cosmic rays, their multi-messenger signatures, and present an overview of both observational data and theoretical models of diffuse emission from the Galaxy.

Speaker: Dmitri SEMIKOZ

10:30 → 11:00 Coffee

11:00 → 12:00 Plenary session

11:00 Cosmic-ray escape from accelerators: the case of pulsar wind nebulae and TeV gamma-ray halos

The escape of particles from their accelerators is a major open problem in cosmic-ray physics. It is intrinsically connected to the ability of sources to accelerate particles up to very high energies, and influences deeply the spectrum released in the interstellar medium, the propagation in the source region, and all direct and indirect observables of the phenomenon. The study of these phenomena is made particularly
challenging both for theory and simulations due to their multi-scale and non-linear nature.
Middle-aged pulsar wind nebulae constitute a unique laboratory to investigate particle escape.
Indeed, the detection of bright X-ray filaments protruding from a number of bow-shock pulsar wind nebulae and of extended TeV gamma-ray halos around a few middle-aged pulsars is now unambiguously understood as resulting from relativistic leptons released from these objects and challenged our current understanding of escape and transport.
In this talk, I will discuss the theoretical issues that emerged from these observations, the main ideas that have been put forward to explain them, and how current and future gamma-ray detectors could help in discriminating among different theoretical models.

Speaker: Sarah Recchia (INAF)

11:30 Highlights of 10 years of observations with CALET on the International Space Station

The CALorimetric Electron Telescope (CALET) is a high-energy astroparticle physics experiment in operation on the International Space Station (ISS) since 2015 with excellent and continuous performance. Designed to measure the spectra of electrons+positrons up to 20 TeV (and gamma rays up to 10 TeV), CALET is searching for possible nearby sources of high-energy electrons and dark matter signatures. Unexpected deviations from a power-law were observed not only for electrons (around 1 TeV), but also in the spectra of proton, helium, and heavier cosmic nuclei. With a precise measurement of their charge, cosmic nuclei can be identified and their spectra measured up to the PeV energy scale, contributing to the study of galactic cosmic-ray acceleration and propagation. CALET also measures the relative abundances of ultra-heavy galactic cosmic rays (UHGRC) above atomic number Z=28 (nickel) and past Z=40 (zirconium).
Here, we present the highlights of the CALET latest science results stemming from almost 10 years of spectral observations of cosmic leptons, hadrons, and photons. Some recent results on the observations of solar modulation will also be included, together with the study of space-weather phenomena, X-ray and soft gamma-ray transients, and searches of electromagnetic counterparts of LIGO/Virgo gravitational wave events. Characterization of on-orbit performance, with approximately 20 million events above 10 GeV recorded per month, will be reported.

Speaker: Pier Simone Marrocchesi (Universita degli studi di Siena (IT))

12:00 → 13:20 Lunch

13:20 → 14:50 CRD: experimental results: secondary CR and transport

13:20 Properties of Secondary Cosmic Ray Nuclei: Thirteen-year Results from the Alpha Magnetic Spectrometer

We present high statistics measurements of the secondary cosmic rays Lithium, Beryllium, Boron, and Fluorine. The properties of the secondary cosmic ray fluxes and their ratios to the primary cosmic rays Li/C, Be/C, B/C, Li/O, Be/O, B/O, and F/Si , are presented. The comparison with the latest theoretical models is also presented.

Speaker: Dr Erwan Robyn (Universita e INFN, Bologna (IT))

13:35 Measurement of the boron spectrum and the boron-to-carbon and boron-to-oxygen flux ratios with 9 years of on-orbit data of the DAMPE space mission.

The precise measurement of secondary cosmic ray (CR) fluxes provides crucial insights into the propagation and interaction of high-energy particles in the Galaxy. Primary CRs—such as carbon and oxygen nuclei—are believed to interact with the interstellar medium (ISM) and fragment into lighter secondary CRs. Boron is one of the most abundant elements among secondary CRs and its spectrum serves as a valuable probe for CR propagation and interactions.

Among all current space-born CRs observatories, the DArk Matter Particle Explorer (DAMPE)—in activity since December 2015—is the one with the deepest calorimeter, enabling the direct measurement of CR spectra up to hundreds of TeV.

We present the direct measurement of the CR boron spectrum, as well as the boron-to-carbon and boron-to-oxygen flux ratios, from 10 GeV/n up to $\sim$8 TeV/n, based on 9 years of on-orbit data collected by the DAMPE mission, thus significantly extending the energy range with respect to previous experiments.

Speaker: Andrea Serpolla (Universite de Geneve (CH))

13:50 Analysis of secondary cosmic ray lithium and beryllium with the DAMPE mission

DAMPE (DArk Matter Particle Explorer) is a space-based particle detector launched in December 2015 to observe high-energy electrons, gamma rays, and cosmic rays. Secondary cosmic ray fluxes serve as key probes of the propagation and interaction of high-energy particles in the Galaxy. Spectral measurements of secondary nuclei, such as lithium, beryllium, as well as their ratios to primary fluxes, are fundamental for improving our understanding of cosmic ray acceleration and propagation. This work presents the latest results from DAMPE’s data analysis, including the spectral measurements of lithium and beryllium and their ratios, spanning energies from a few dozen GeV/n to several TeV/n with 9 years of DAMPE flight data.

Speaker: En-heng Xu (University of Science and Technology of China)

14:05 Measurement of Cr and Ti fluxes and sub-iron/iron flux ratios with CALET on the International Space Station

The analysis of cosmic ray nuclei provides critical insights for a theoretical
understanding of the acceleration and propagation mechanisms of charged particles in
our Galaxy. A unique source of information on the average path length that cosmic
rays travel before reaching Earth can be provided by the elements lying just below iron
in the periodic table (sub-iron). These elements are believed to be produced by the
spallation of heavier nuclei as they propagate in the interstellar medium. The
Calorimetric Electron Telescope (CALET), which has been operational on the
International Space Station since 2015, has collected a substantial dataset comprising
cosmic-ray (CR) iron and sub-iron events across a broad energy spectrum. In this
contribution we present the measurements of the energy dependence of the titanium
and chromium fluxes in cosmic rays, as their flux ratios to iron, in the energy interval
from 10 GeV/n to 250 GeV/n. The measurements, based on data collected during eight
years of operation, are reported with significantly enhanced precision compared to
existing measurements, including a detailed assessment of systematic uncertainties. In
addition to the sub-iron fluxes, an update of CALET's analysis of the iron flux has
been carried out up to 1.6 TeV/n.

Speaker: Francesco Stolzi

14:20 Galactic cosmic rays and cross-sections from accelerators

The last generation of Galactic cosmic-ray experiments is providing a wealth of high-precision new data. The interpretation of these data is stimulating a very rich and active debate in the community, with strong discovery and constraining potentials on many topics (dark matter, acceleration and transport of cosmic rays, Galactic sources etc.). However, the consensus in the community is that these interpretations are strongly limited by nuclear cross-section uncertainties.
The XSCRC (Cross-Section for Cosmic Rays at CERN) workshop series https://indico.cern.ch/event/1377509/ aims at bringing together experimentalists, phenomenologists, and theorists from various communities (astroparticle, particle physics, nuclear physics, etc.), to build synergies and provide a detailed road map to close the most urgent gaps in cross-section data, in order to efficiently progress on many open physics cases. In this talk, I will present the main outcomes from the 2024 edition, which are going to appear in a comprehensive white paper. In particular, I will discuss the most relevant physics cases and which cross sections are the most urgent to measure at high precision.

Speaker: Prof. Fiorenza Donato (Torino University & INFN, & CERN)

14:35 Fragmentation Cross Sections for the Understanding of Cosmic-Ray Transport in the Galaxy: Results and Prospects from NA61/SHINE

Accurate measurements of cosmic-ray fragmentation cross sections are essential for maximizing the physics potential of precise measurements of secondary and primary cosmic-ray fluxes from current balloon and spaceborne experiments. NA61/SHINE, operating at the CERN SPS H2 beamline, is uniquely suited for studying these interactions at high energies above 10 GeV/nucleon.

In this contribution we will present the fragmentation cross sections of carbon to 10B, 11B and 11C at 13 GeV/nucleon, crucial for interpreting the cosmic-ray boron-to-carbon (B/C) ratio. These findings are based on data from a pilot run conducted in 2018. Additionally, we report on preliminary results from 2024 measurements covering projectile nuclei ranging from lithium to silicon. With over 40 million recorded events, this dataset will enable the reconstruction of the full reaction network required to study light secondary cosmic rays. Finally, we discuss prospects for extending these measurements to heavier projectiles, including iron.

Speaker: Michael Unger (Karlsruhe Institute for Technology)

13:20 → 14:50 CRI: extensive air shower laboratory

13:20 Review of Very High Energy Cosmic Ray Air Shower Studies of the LHAASO Observatory

The large high altitude air shower observatory has comprehensively measured the information of the air showers of very high energy cosmic rays. Several important results regarding the air shower already have been published. A cosmic ray mass independent energy reconstruction method has been proposed by combining the muon content and the electromagnetic particles (or Cherenkov light) of the air shower. The mean logarithmic mass of the cosmic ray also has been estimated based on the muon content of the air shower. Also, the attenuation length of muon content in the air shower has measured and compared with expectations of several hadronic interaction models. The fluctuation of the muon content of the air shower has been used to estimate the variance of logarithmic mass of the cosmic ray. This talk will summarize all the aforementioned air shower studies.

Speaker: Cunfeng Feng (Shandong University (CN))

13:35 Latest results by the FASER experiment and their implication for forward hadron productions

The muon puzzle, the excess of the number of muons with respect to simulations in ultra-high energy cosmic rays, was initially reported by the Pierre Auger Observatory in 2015 and confirmed by more recent analyses. This suggests that forward meson production in hadronic interactions is not fully understood. Most scenarios to solve this issue predict less production of forward neutral pions and more production of forward kaons (or other particles) instead.
The FASER experiment at the LHC is sensitive to neutrinos and muons, which are the decay products of forward charged pions and kaons. Recently, the FASER experiment published first measurements of muon and electron neutrinos. By combining these measurements, we can give constraints on forward hadron production, which is a key to solving the muon puzzle. In this talk, we report the latest results from the FASER experiment and their implication for forward hadron productions.

Speaker: Ken Ohashi (Universitaet Bern (CH))

13:50 Status and Prospects of the LHCf experiment

Precise knowledge of high energy hadronic interaction is an important key to understand air shower development. The LHCf experiment measures neutral particles such as photons, neutral pions, and neutrons, produced in the very forward region of LHC collisions, which contribute to the air shower development. Since the LHC start, LHCf performed many operations with pp collisions at several collision energies from 0.9 to 13.6 TeV and pPb.

The last and most important operation of LHCf, with proton-oxygen collisions which is an ideal condition to study interactions between high-energy cosmic-rays and atmospheric nucleus, will be performed in July 2025, just before this conference. The LHCf-Arm2 detector will be installed in the proton remnant side, and approximately 100 M events are expected to be recorded in 2 days of data taking together with ATLAS. We will report prospects and flesh news of this operation as well as current analysis activities using data obtained in the past.

Speaker: Hiroaki Menjo (Nagoya University (JP))

14:05 EPOS LHC-R : a global approach to solve the muon puzzle

The hadron production in the simulation of extensive air showers is a long standing problem and the origin of large uncertainties in the reconstruction of the mass of the high energy primary cosmic rays. Hadronic interaction models re-tuned after early LHC data give more consistent results among each other compared to the first generation of models, but still can't reproduce extended air shower data (EAS) consistently resulting in the so-called "muon puzzle". Using more recent LHC data like in the QGSJET-III model improve further the description of EAS by such a model but is not enough to resolve the discrepancy. On the other hand, the EPOS project is a theoretical global approach aiming at describing data from very fundamental electron-positron interactions to central heavy ions collisions. We will demonstrate that this approach can provide new constraints, changing the correlation between the measured data at mid-rapidity and the predicted particle production at large rapidities, which drive the EAS development. Thus, using the same accelerator data, different predictions are obtained in air shower simulations in much better agreement with the current air shower data (for both the maximum shower development depth Xmax and the energy spectrum of the muons at ground). Using the EPOS LHC-R model, the detailed changes will be addressed and their consequences on EAS observable at various energies.

Speaker: Dr Tanguy Pierog

14:20 A new approach to modeling cosmic ray interactions

We present a new approach to modeling cosmic ray (CR) interactions, which relies on a very basic interaction picture, while using a reasonable and transparent formalism, in the framework of the Reggeon Field Theory. Our main motivation is to provide a new CR interaction model characterized by relatively transparent physics, sufficient parameter flexibility, and high computational efficiency, which can be easily managed by external users, including a re-tuning of the model parameters. Such a model can be used for studying potential modifications of the interaction treatment, necessary for describing particular sets of data on extensive air showers (EAS) initiated by high energy cosmic rays, at a microscopic level, thereby keeping a consistency with general restrictions, like the unitarity, energy-momentum and charge conservation, Lorentz and isospin invariance. Importantly, this should allow one to study a compatibility of such modifications with relevant accelerator data. The preliminary version of the new model is presented and its results for particle production and for EAS characteristics are discussed.

Speaker: Sergey Ostapchenko (Frankfurt Institute for Advanced Studies (FIAS))

14:35 A Universal Mapping Between Proton-Air Interaction Variables and Air Shower Observables: Depth of Shower Maximum and Muon Content

We introduce a set of new multiparticle production variables derived from the energy spectrum of secondary hadrons in ultra-high-energy proton-air interactions. The distributions of these variables can be measured within the phase space accessible to particle detectors in accelerator experiments and are highly dependent on the hadronic interaction model. Furthermore, we demonstrate a precise, hadronic-model-independent mapping between these variables and the joint distribution of the depth of shower maxima and the number of muons in extensive air showers. This enables the use of air shower measurements to constrain hadron production in kinematic regimes beyond the reach of human-made colliders.

Speaker: Miguel Martins

13:20 → 14:50 CRI: lightning

13:20 Optical Emissions Associated with Terrestrial Gamma-ray and Lightning Flashes at the Telescope Array Detector.

Terrestrial Gamma-ray Flashes (TGFs) are intense bursts of gamma rays originating in Earth's atmosphere, often associated with lightning activity during thunderstorms. These flashes are believed to result from relativistic runaway electron avalanches triggered by strong electric fields. In this study, we analyze multiple TGFs observed at the Telescope Array Surface Detectors site using a suite of instruments, including a fast antenna, a Lightning Mapping Array, a high-speed camera, and a spectroscopic system. Our focus is on the time-resolved leader spectra of the optical component linked to downward TGFs, covering the 400–900 nm range during the 2022 and 2023 lightning seasons. The spectra reveal that emissions from singly ionized nitrogen and oxygen appear before and after TGF detection, while neutral emissions coincide with the moment of TGF detection. Additionally, we report the first observations captured by the photometric array at 337, 391, and 777 nm. Observations from the spectroscopic system and the photometric array provide valuable insights into the mechanisms driving lightning and TGF initiation and propagation. These findings highlight key optical signatures associated with TGFs, offering new perspectives on their behavior during thunderstorm activity.

Speaker: Rasha Abbasi (Loyola University Chicago)

13:35 Simultaneous observations of multiple ELVES and SPRITES at the Pierre Auger Observatory

Since 2014, the Pierre Auger Observatory has exploited a dedicated trigger, and its very high time resolution to do studies on ELVES and harvest record samples of multiple ELVES using the Fluorescence Detector (FD). In 2017, after extending the readout of trace lengths to 0.9 ms, we started observing other types of light transients from the base of the ionosphere, such as HALOS, which deserved further investigation. In December 2023 and April 2024, we installed two additional cameras (TLECAMs), which allow us to perform simultaneous detection of these transients with higher space resolution and longer integration times. Here we present our first simultaneous observations of SPRITES and ELVES by both TLECAMs and FD. Furthermore, we describe the Python algorithm based on DBSCAN to automatically detect SPRITES in the videos recorded by our TLECAMs and acquire data efficiently without needing the FD trigger.

Speaker: Dr Roberto Mussa (INFN Torino)

13:50 Investigation of the connection between gamma-ray glow and cosmic-ray in the next generation “thundercloud project”

The connection between cosmic ray air showers and thunderclouds has become a major research topic in recent years in high-energy atmospheric physics.
One of the open questions is whether cosmic rays are involved in triggering a “gamma-ray glow”. A “gamma-ray glow” is a phenomenon in which gamma-ray increases for tens of seconds to several minutes during the passage of thunderclouds. A strong electric field is generated by charge separation in the developed thundercloud. When high-energy seed electrons pass through this region, electrons are accelerated and amplified to relativistic speed. Relativistic electrons interact with the atmosphere, producing gamma rays by bremsstrahlung, which reach the ground. The origin of these seed electrons is still unknown, but one candidate is thought to be electrons from cosmic ray air showers.
To track moving thunderclouds, Citizen Science “Thundercloud Project” has installed about 70 gamma-ray detectors “Cogamo” along the Japan Sea coast area in winter since 2018. The Cogamo detectors are equipped with 5×5×15 cm CsI (Tl) scintillators and store radiation event data with a time resolution of 100 μs and housekeeping data every 10 seconds. This multi-point observation has revealed temporal changes in gamma-ray glow such as the growth, disappearance, as well as spatial distribution of the height and size of the electron acceleration region in thunderclouds.
In the FY2024 observations, in addition to the previous mapping observations of the Cogamo detectors, a new detector was installed at Kanazawa University to investigate the relationship between cosmic ray air showers and gamma-ray glow. This detector can discriminate between charged particles and gamma rays using the MoMoTarO board, which is being developed for lunar water resources exploration and can acquire 4-channels event data with a time resolution of 100 ns. A plastic scintillator EJ200 (5×15×1 cm) is mounted under the CsI (5×5×15 cm) scintillator so that charged particles and gamma rays from the vertical direction can be discriminated by 2-channel coincidence. To detect photonuclear reactions (Enoto et al.,2017), a plastic scintillator EJ270 (5×5×1 cm) doped with Li, which can detect neutrons, is mounted. GAGG (2×2×1 cm) is also installed to detect TGF(terrestrial gamma-ray flash), which has a large count rate within several ms.
Around 21:30 on February 19, 2025, a gamma-ray glow with a duration of about 2 minutes was detected with the new detector, mainly by the CsI(Tl) scintillator. A similar gamma-ray glow was also observed at the nearby Cogamo detector, which was located about 1 m away from the new detector. The maximum count rate was about 2-2.5 times the background, which was weak among the glows observed in Kanazawa. At this time, EJ200 showed an intensification of about 1.1 times from the background level.There was no noticeable intensification in the count rate of the EJ270 scintillator. A slight brightening was observed by the small effective area GAGG.
In this talk, I will report the results of the gamma-ray glow observations with the new detector and summarize improvements for next year's observation plan.

Speaker: Miwa Tsurumi (Kyoto University)

14:05 Analyze thunderstorm events based on the experimental data from LHAASO-WCDA

Thunderstorms are intense localized convective weather phenomena, typically accompanied by strong lightning, high-energy electromagnetic radiation, and dramatic variations in atmospheric electric fields. Terrestrial Gamma-ray Flashes (TGFs) and Thunderstorm Ground Enhancements (TGE) represent high-energy radiation phenomena generated during thunderstorms. The extreme electric field fluctuations triggered by thunderstorm activity (peaking at -1700 V/cm) can modify the propagation of secondary cosmic particles, altering their arrival times, spatial distributions, and energy spectra at ground level. The Large High Altitude Air Shower Observatory (LHAASO), located in Daocheng County, Sichuan Province, China – a thunderstorm-prone region – hosts the Water Cherenkov Detector Array (WCDA) comprising 3,120 tightly packed detectors covering 78,000 m², with a cosmic ray event detection threshold of ~100 GeV. Data analysis from May 2021 to September 2024 reveals a maximum event rate reduction of 20% during thunderstorms in WCDA observations, exhibiting distinct anisotropic characteristics: systematic discrepancies in reduction magnitude across different azimuthal and zenith angles, with spatial distributions demonstrating temporal evolution as storms develop. Energy-dependent analysis shows more pronounced event rate reductions in the lower energy range compared to higher energies.This paper synthesizes the findings from three years of LHAASO-WCDA cosmic ray data analysis during thunderstorms and discusses potential underlying mechanisms for these anomalies, including electric field modulation of particle transport and possible thunderstorm-induced atmospheric shielding effects.

Speaker: Baining Xu

14:20 Characterization of downward TGFs detected at the Pierre Auger Observatory

Downward TGFs are sub-millisecond bursts of MeV gamma rays produced in thunderclouds. According to the Relativistic Runaway Electron Avalanche model, gamma rays are produced, via bremsstrahlung, from electron cascades activated by a relativistic “seed” electron. It is not clear what mechanism is responsible for the acceleration of electrons to relativistic energies in electric discharges. To better understand the acceleration sites and the TGF production mechanisms, it is critically important to identify the TGF source position and geometry in the atmosphere and study the gamma emission characteristics. The Surface Detector of the Pierre Auger Observatory, with its 1600 Water-Cherenkov detectors very sensitive to high-energy photons and with a very fine time-sampling, is a valuable instrument to study downward TGFs. The possibility to analyze the radiation emission in detail led to the observation of the first TGFs with an asymmetric azimuthal structure, suggesting a complex source different from the initially hypothesized downward beam. We report on these observations and the new perspectives that the incorporation of new instruments at the Auger site to study lightning development alongside gamma emission, and the increasingly detailed data provided by satellites and global lightning networks could open.

Speaker: Roberta Colalillo

14:35 The Atmosphere and Radiation: Screening or Generating?

It is commonly understood that the atmosphere protects the Earth from harmful radiation. However, the atmosphere not only absorbs the vast energy of galactic cosmic rays but also serves as a source of particle generation, producing significant fluxes of electrons, gamma rays, and neutrons. These particles are generated through several mechanisms, including relativistic runaway electron avalanches (RREA), manifesting as thunderstorm ground enhancements (TGE) when detected on the Earth's surface, and radon progeny gamma radiation.

The Global Electric Circuit (GEC) governs enhanced particle fluxes of atmospheric origin. Thunderstorms create strong electric fields that extend across large areas within and around storm systems. Charge separation in thunderclouds, driven by updrafts of warm air and interactions among hydrometeors, generates oppositely directed dipoles within the cloud. The atmospheric electric field comprises upper and lower dipoles, accelerating free electrons toward both open space and the Earth's surface.

Free electrons are abundant in the troposphere. Electric fields induced by strong thunderstorms transfer energy to these electrons, accelerating them and, under specific conditions, forming electron-photon avalanches. These avalanches propagate through large atmospheric volumes and extend across extensive areas upon reaching the Earth's surface, significantly increasing the intensity of natural gamma radiation (NGR). These enhancements can last from seconds to tens of minutes. The ionized channels created by these avalanches provide pathways for lightning leaders to propagate toward the ground.

New observations on Aragats have revealed a previously overlooked intense gamma-ray source in high-altitude and polar environments. This novel wind-driven radiation mechanism (Wind-TGE) differs from relativistic runaway electron avalanches and conventional radon progeny radiation models. Strong winds and dry, electrified snow concentrate gamma rays into a dense radioactive cloud that persists for many hours, enhancing NGR levels by more than 1000%. Total fluence can reach 2×107 gammas/cm² and more.
Understanding these newly observed phenomena is critical for atmospheric physics, space weather studies, and environmental monitoring. This underscores the need for dedicated research into the interactions among snowstorms, radon transport, and atmospheric electricity.

Speaker: Ashot Chilingarian

13:20 → 14:50 GA: AGNs

13:20 An unbiased survey of high-frequency-peaked BL Lac objects with VERITAS

More than 50 high-frequency-peaked BL Lac objects (HBLs) have been detected by ground-based TeV gamma-ray observatories, making them the dominant population of extragalactic sources observed at energies above 0.1 TeV. The fluxes of HBLs are often reported only during high-flux states, biasing our understanding of the properties and duty cycle of these sources towards flares. In recent years, the VERITAS observatory has conducted an observing campaign of 36 X-ray selected HBLs, aiming to produce the first unbiased survey of HBLs at TeV energies by finding an estimate of the average TeV flux for each source, while also searching for detections of new TeV blazars. The VERITAS HBL sample consists of 21 known TeV sources and 15 blazars without previously reported TeV emission at the time of the source selection (three of which have since been announced as new detections by VERITAS). A total of 13 blazars are significantly detected in the unbiased survey dataset, which includes the first detection of the blazar RBS 1366 at TeV energies. We find that 11 sources that have been detected during flaring episodes do not show detectable levels of TeV emission when only untriggered observations are considered. The results of the full survey will be first presented in this contribution.

Speaker: Pazit Rabinowitz

13:35 Exploring the Most Extreme Blazars: New Insights from MAGIC

Extremely high-peaked BL Lac objects (or extreme blazars) are unique extragalactic laboratories where particle acceleration processes are pushed at their physical limits. In these blazars, synchrotron emission peaking above keV energies is reprocessed to very-high-energy (VHE, energies > 100 GeV) gamma rays, often resulting in very hard TeV spectra. Over the past two decades, they have attracted a growing interest from the scientific community, both experimentally and theoretically, as crucial targets for understanding the diversity within the blazar class.
On the experimental side, new sources have been detected and characterized, populating the extreme blazars class. Notably, VHE campaigns have revealed evidence of emerging spectral differences in this energy band, suggesting inhomogeneity within this class of sources. Recent studies have also unveiled intriguing differences in the temporal evolution of their spectral emission. On the theoretical side, these spectral differences are challenging the current standard emission and acceleration models for blazars, suggesting the need for more complex theoretical frameworks.
In this contribution, we present the latest results from recent MAGIC Collaboration observing campaigns aimed to enlarge the extreme blazars population at VHE and understand the origin of their extreme properties. Furthermore, we will present the results of the most recent observations, discussing analogies and differences with well-known sources such as the archetypal 1ES 0229+200, as well as interpretations of their non-conventional spectral emission.

Speaker: Luca Foffano (INAF Rome (IAPS))

13:50 VERITAS observations of changing-look blazars

Changing-look (transitional) blazars shift between subclasses at different flux states. It is, therefore, crucial to study them to comprehend the fundamental physics governing blazars and the relationships between their different subclasses. VERITAS has detected very-high-energy (VHE; E>100 GeV) emissions from several transitional blazars during flaring states, revealing their capability of particle acceleration and relevance to the VHE astrophysics domain.
We present the results of our recent studies of VHE timing and spectral properties of flaring transitional blazars observed with VERITAS, including OP 313 and BL Lac. VERITAS closely monitored OP 313 during its January 2025 flare and BL Lac during its October 2024 flare. To complement these observations, we incorporate multiwavelength data from Fermi-LAT, Swift-XRT/UVOT, and other ground-based telescopes to construct their broadband spectral energy distributions (SEDs). By modeling these SEDs, we aim to investigate the physical mechanisms driving their transitional behavior and emission processes.
Our findings provide key insights into the particle acceleration mechanisms in these sources and the physical parameters responsible for the transition between different subclasses.

Speaker: Ashwani Pandey (University of Utah)

14:05 Review of extragalactic sources detected by LHAASO-WCDA

Key sources of VHE gamma rays include extra-galactic objects such as blazars, gamma-ray bursts (GRBs), and other interesting transients phenomena. The studies on these targets provides critical insights into astrophysical phenomena, including black hole accretion, particle acceleration, and explosion dynamics. The Large High Altitude Air Shower Observatory (LHAASO), located in China, is a multi-purpose facility designed to detect cosmic rays and gamma rays in the energy range from a few hundred GeV to a few hundred PeV. As one of three sub-arrays comprising LHAASO, the Water Cherenkov Detector Array (WCDA), Its wide field of view, high duty cycle, and high sensitivity of LHAASO-WCDA provides an ideal platform for capturing these flaring phenomena, contributing to a deeper understanding astrophysical phenomena. In this talk, we will review the extragalactic sources detected by LHAASO-WCDA, along with a preliminary catalog of these sourcesl. Additionally, we will discuss transient event handling, including the monitoring framework, analysis pipeline, and preliminary results.

Speaker: Min Zha

14:20 HEGS : Revisiting a decade of H.E.S.S. extragalactic observations

During its first phase, from 2004 up to the end of 2012, the H.E.S.S. (High Energy Stereoscopic System) experiment observed the extragalactic skies for more than 2700 hours. These data have been re-analysed in a single consistent framework, leading to the derivation of a catalog of 23 sources. In total, about 6.5% of the sky was observed, allowing for several additional studies to be conducted: source variability, extragalactic gamma-ray background light, and comparison with the Fermi-LAT catalogues. In this contribution, we will discuss these results and present the high-level data (catalogs, maps) released to the astrophysical community.

Speaker: François Brun (IRFU, CEA, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France)

14:35 Recent Highlights from the VERITAS AGN Program

VERITAS is one of the world’s most sensitive very-high-energy (VHE; E > 100 GeV) gamma-ray observatories. Over 8,600 hours (~50%) of its good-weather observations were targeted on active galactic nuclei (AGN). These observations include an ongoing, comprehensive program to discover new VHE AGN, target-of-opportunity responses to flaring AGN, and both monitoring and deep campaigns on known VHE AGN. For these studies, the VERITAS collaboration leverages its VHE spectral and variability measurements, and accompanying broadband observations to probe the underlying jet-powered processes in AGN. Recent scientific highlights from the VERITAS AGN program, including any new announcements, will be presented.

Speaker: Wystan Benbow

13:20 → 14:50 GA: space experiments

13:20 The Anti Coincidence Detector for the Antarctic Demonstrator for APT (ADAPT)

The Antarctic Demonstrator for the Advanced Particle-astrophysics Telescope (ADAPT) is a NASA suborbital mission scheduled for a high-altitude balloon flight over Antarctica during the 2025-2026 season. ADAPT aims at validating key detector technologies for the forthcoming space-based Advanced Particle-astrophysics Telescope (APT) mission, an MeV-TeV gamma-ray telescope designed to provide an order of magnitude improvement in sensitivity over any current mission, with a focus on dark matter and multimessenger science.

A segmented anti-coincidence detector (ACD) covers the ADAPT instrument to identify gamma rays against the charged cosmic-ray background (mainly protons), thereby enhancing the detection sensitivity to gamma-ray events. A secondary objective of the ACD is to identify heavy nuclei that exploit the proportionality of the energy deposition to Z^2, being Z the atomic number of the nuclei. The ACD consists of a set of plastic scintillator tiles coupled with Silicon Photomultipliers (SiPMs), arranged to envelop the detectors in a configuration that ensures the veto of charged particle interactions while providing complementary measurements for nuclei identification.

This presentation will explore the technical specifications and design considerations of the ADAPT ACD, as well as its expected performance, which has been extensively evaluated through simulation modeling, tests in the laboratory, and with beam particles.

Speaker: Leonardo Di Venere (Universita e INFN, Bari (IT))

13:35 Design and Performance Assessment of the Antarctic Demonstrator for APT (ADAPT): A Next-Generation Gamma-Ray space-borne Telescope

The astrophysical community is currently focusing on the development of next-generation gamma-ray telescopes designed to detect low-energy photons in the MeV-GeV range, operating in both the Compton and pair conversion regimes. The proposed Advanced Particle-astrophysics Telescope (APT) is a planned space-based, MeV-TeV gamma-ray mission aimed at providing an order of magnitude improvement in sensitivity over any current mission with a design optimized for dark-matter and multimessenger science. The APT collaboration is an international team focused now on designing and building a high-altitude balloon-borne prototype, the Antarctic Demonstrator for APT (ADAPT), which is anticipated to fly in the 2026-27 season. The current design of the ADAPT instrument includes an imaging CsI calorimeter (ICC) and a scintillating fiber tracker. An ICC module is composed of a 3x3 array of 150 mm x 150 mm x 5 mm CsI(Na) tiles, with top and bottom surfaces covered by 2 mm wavelength-shifting (WLS) fibers, oriented orthogonally along the x- and y-axes and read out by silicon photomultipliers (SiPMs). The ICC modules also have edge-mounted SiPMs for calorimetry. The fiber tracker consists of 1.5 mm round scintillating fibers, arranged in two interleaved layers for both the x- and y-coordinates. Additionally, the ADAPT design includes a Silicon Strip Detector (SSD) to enhance Compton reconstruction and cosmic ray (CR) measurements. The instrument is also equipped with an Anti-Coincidence Detector (ACD) made of plastic scintillators as an outermost detector. The ACD's primary role is to discriminate gamma rays from charged particles and provide complementary measurements for nuclei identification. The performance of each sub-detector, as well as the overall performance of ADAPT, has been extensively evaluated through simulation modeling, laboratory tests, and beam tests. In this contribution, we present an overview of the current design of the ADAPT instrument, its scientific objectives, and its ongoing performance assessment (with a focus on event reconstruction in the Compton regime and real-time gamma-ray burst localization).

Speaker: Davide Serini (INFN - National Institute for Nuclear Physics)

13:50 POLAR-2 – Latest Developments of the Next Generation GRB Polarimeter

Gamma-Ray Bursts (GRBs) are among the most energetic events in the Universe. Despite over 50 years of research and measurements their prompt emission remains poorly understood, with key questions surrounding the structure of relativistic jets, magnetic field configurations, and dominant radiation mechanisms. Polarization measurements are critical in resolving these uncertainties. The POLAR mission, operational in 2016-2017 on Tiangong-2, provided the most statistically significant GRB polarization data. Its results indicated low time-averaged polarization with hints of temporal evolution. However, POLAR’s limited sensitivity, small effective area, and restricted energy range prevented more detailed time- and energy-resolved analyses in addition to a larger sample of GRB polarization measurements. POLAR-2 is designed to address these limitations by offering a fourfold increase in effective area (at least) and an extended energy range of 30–800 keV by utilizing Silicon Photomultipliers (SiPMs) and an updated module design, enabling the differentiation of competing GRB emission models. The instrument comprises of 100 polarimeter modules (each with 64 plastic scintillator bars), wherein the polarization angle is extracted through Compton Scattering of the gammas. The polarimeter module design was validated during an ESRF beam test campaign in 2023. The instrument was developed by a joint effort of Switzerland, China, Poland and Germany and is planned for launch in 2027. Currently, POLAR-2 is in its production phase with the first module targets being produced. We will provide an overview of the current status of the development.

Speaker: Philipp Azzarello (Département de Physique Nucléaire et Corpusculaire (DPNC), Université de Genève, 24 quai Ernest-Ansermet, CH-1211 Genève 4, Switzerland)

14:05 DR-TES: Balloon-Borne TES Microcalorimeter Mission for Gamma-Ray Detection

DR-TES (Dilution Refrigerator - Transition Edge Sensors) is a balloon-borne experiment aimed at demonstrating advanced cryogenic and detector technologies for X-ray and gamma-ray spectroscopy in a near-space environment. The mission utilizes a low-temperature TES detector array, cooled to ~75 mK by a miniature dilution refrigerator (mini-DR), which itself is pre-cooled by a liquid helium cryostat. During pre-flight calibrations, the TES array, read out by Superconducting Quantum Interference Devices (SQUIDs) and microwave-multiplexed electronics, achieved an energy resolution of ~70 eV FWHM at 97 keV.

On September 24, 2024, DR-TES completed a one-day balloon flight, maintaining operational temperatures between 75 mK and 100 mK for nearly 90% of the total flight time, and demonstrated excellent cryogenic stability. The TES detector array successfully recorded X-ray and gamma-ray signals from an onboard radioactive source, confirming the TES array's capability to operate in a space-like environment.

This presentation covers the objectives of the mission, experimental setup, pre-flight performance, and in-flight results. We emphasize the first successful demonstration of a TES microcalorimeter array for X-ray and gamma-ray detection, cooled by a mini-DR system, in a near-space environment aboard a stratospheric balloon. These results establish a foundation for future high-energy astrophysics investigations with balloon-borne and space-based cryogenic TES missions.

Speaker: Sohee Chun (Washington University in St. Louis)

14:20 WINK: Advancing X and Gamma Ray Detection Technology for Space Observations

WINK is a proof of concept prototype designed to test, enhance and approve the base technology of Crystal Eye. While Crystal Eye is intended for all-sky monitoring of X and gamma rays in the 0.1–30 MeV range, whose primary objectives include investigating the prompt emissions of Gamma Ray Bursts (GRBs) - and acting as pointing system for other detectors in order to study the associated afterglow - and studying EM signals associated with extreme cosmic phenomena, WINK will contribute to the characterization of the cosmic background and, when directed toward Earth, will allow the study of atmospheric phenomena such as Terrestrial Gamma-Ray Flashes (TGFs).

The WINK system consists of three full pixels of the original concept of Crystal Eye: each pixel is composed of two layers of LYSO crystal, each read by Silicon Photomultipliers (SiPMs), and an anti-coincidence system. The final instrument will feature 112 pixels arranged on a hemispherical surface with a 14 cm radius, providing a wide field of view (FoV) and high localization accuracy.

WINK is scheduled to operate for two months in low Earth orbit (LEO) aboard Space Rider (SR), an ESA vehicle. Positioned within the module, it will have a 30° FoV, enabling crucial field tests to refine the final detector’s design. The WINK qualification model has been developed and built, featuring a space-qualified electronic board and updated software, and will enble further testing to enhance performance and reliability. In this contribution, we present the initial test results along with progress on the qualification model.

Speaker: Matteo Tambone (Università degli Studi di Napoli Federico II, INFN Sezione di Napoli)

14:35 Gamma-ray observations with DAMPE

The DArk Matter Particle Explorer (DAMPE) is a spaceborne high-energy particle detector launched on December 17, 2015, as part of an international collaboration led by the Chinese Academy of Sciences. DAMPE is designed to investigate cosmic-ray electrons and γ-rays with unprecedented energy resolution and sensitivity. By operating in low Earth orbit at an altitude of approximately 500 km, DAMPE provides continuous observations of the high-energy sky, significantly contributing to our understanding of astrophysical and fundamental physics phenomena.

DAMPE observes the γ-ray sky over a broad energy range, from approximately 2 GeV to 10 TeV, with a maximum acceptance of 1800 cm² sr. The payload consists of a sophisticated set of detectors, including a plastic scintillator detector (PSD), a silicon-tungsten tracker (STK), a BGO calorimeter, and a neutron detector, which together enable precise measurement of incoming particles' energy, trajectory, and identity. These capabilities allow DAMPE to explore a variety of astrophysical sources and processes with high precision.

Over its nine years of operation, DAMPE has completed approximately 18 full-sky surveys, collecting an extensive dataset that has deepened our understanding of high-energy cosmic phenomena. In particular, the continuous accumulation of observational data has led to a refined calibration of the Instrumental Response Functions (IRF), enhancing the accuracy of measurements and enabling more precise scientific analyses. The in-flight calibration, made possible by a comprehensive understanding of the payload, has led to significant improvements in DAMPE’s ability to detect and analyze γ-ray sources.

The scientific impact of DAMPE extends across multiple research areas. One major focus is the search for narrow γ-ray line emissions, which could provide indirect evidence for dark matter annihilation or decay. Additionally, DAMPE has contributed to studies of diffuse γ-ray emissions, shedding light on cosmic-ray interactions with the interstellar medium. The instrument has also played a crucial role in the analysis of point sources, such as active galactic nuclei (AGN) and pulsars, providing valuable insights into their emission mechanisms. Furthermore, DAMPE contributes to transient source monitoring, detecting and characterizing sudden high-energy events, such as γ-ray bursts and flaring AGNs.

In this talk, we present the latest results from DAMPE, highlighting its contributions to high-energy astrophysics and fundamental physics. These findings demonstrate the continued scientific value of DAMPE and its role in advancing our understanding of the γ-ray universe.

Speaker: Fabio Gargano (INFN, Bari (IT))

13:20 → 14:50 NU: experimental & next generation

13:20 Prompt atmospheric leptons and the potential role of intrinsic charm

The all-sky very-high energy ($10^4-10^6$ GeV) atmospheric muon flux is most recently measured by IceCube, where in the higher energy range, the spectrum hardens indicating a prompt component. IceCube also measures the atmospheric muon neutrino flux at high energy. Since this is dominated by the astrophysical flux, they are only able to set an upper bound on the prompt atmospheric muon neutrino flux contribution. We provide a new evaluation of the prompt atmospheric muon flux including for the first time an intrinsic charm component to colliding nucleons. This increases forward production of $\bar{D}^{0}$, $D^-$ and $\Lambda_c$ which decay into final states that can contain muons and muon neutrinos. We show how the increase in the prompt muon flux due to intrinsic charm has an associated increase in the prompt muon neutrino flux. We consider two models for intrinsic charm production, the models of Brodsky-Hoyer-Peterson-Sakai and Regge ansatz, that we implement in MCEq used for the calculation of the lepton fluxes. We discuss the challenges of obtaining predictions that are simultaneously consistent with both IceCube's high energy atmospheric muon flux measurements and their upper bound on the prompt muon neutrino flux. We quantify the discrepancies.

Speaker: Laksha Pradip Das

13:35 Search for the prompt component in the atmospheric muon flux observed by KM3NeT detectors

The network of two next-generation underwater Cherenkov neutrino telescopes: ARCA and ORCA is being successively deployed in the Mediterranean Sea by the KM3NeT Collaboration. The focus of ARCA is neutrino astronomy, while ORCA is mainly dedicated to neutrino oscillation studies. Both detectors are already operational in their intermediate states and collect valuable results. This work explores the potential of intermediate as well as complete detector configurations of ARCA and ORCA to observe the prompt component of the atmospheric muon flux, originating from cosmic ray interactions. It builds upon a dedicated reconstruction of observables characteristic for events composed of multiple muons, called muon bundles. The obtained results show that KM3NeT is sensitive to the prompt muon flux component and should be able to verify its existence within the first few years of data taking with completed detectors.

Speaker: Dr Brían Ó Fearraigh (INFN University of Genoa)

13:50 Calculation of Atmospheric Neutrino Flux at Low Energies

Atmospheric neutrinos play a dual role in particle physics: they are crucial signals for studying neutrino oscillations and serve as significant backgrounds in searches for the diffuse supernova neutrino background, proton decay, dark matter, and other rare processes. To address unresolved questions in neutrino oscillation physics and to identify rare events, precise predictions of atmospheric neutrino flux in the GeV and lower energy ranges are essential. In this talk, I will present the latest results on the calculation of atmospheric neutrino fluxes at sites such as JUNO and Super-Kamiokande. The calculation scheme builds on the methods outlined in [Honda et al., Phys. Rev. D 92, 023004 (2015)], with enhancements to achieve greater precision, particularly in the low-energy regime.

Speaker: Jie Cheng

14:05 Validation of Atmospheric Neutrino Flux via Cosmic Ray Muon Spin Polarization Detector (CRmuSR)

Atmospheric neutrinos (ATNs) are widely studied in the context of neutrino oscillation parameter measurements due to a wide range of propagation baselines and neutrino energies. Determining parameters such as $\theta_{23}$ and $\Delta m_{32}^2$ relies on precise experimental measurements of the atmospheric neutrino flux. The theoretical prediction of ATN flux significantly influences the accuracy of these results. Since ATNs are produced either through the production or decay of cosmic ray muons (atmospheric muons), cosmic ray muons serve as an ideal probe to investigate the production mechanisms of ATNs. By detecting the polarization of cosmic ray muons, we can extract the ratio of their parent particles, such as the $K/ \pi$ ratio. To achieve this, the research group at Sun Yat-Sen University (SYSU) has developed a novel detector system called the Cosmic-Ray Muon Spin Polarization Detector (CRmuSR). CRmuSR employs a modular design to reconstruct the momentum direction of cosmic ray muons and the spatial distribution of Michel electrons. With a time resolution superior to $2 \mathrm{ns}$, the CRmuSR system offers high precision. Additionally, the modular design makes CRmuSR easily deployable as an array, potentially aiding future atmospheric neutrino experiments to investigate the ATN production process within an acceptable period.

Speaker: Mingchen Sun (Sun Yat-Sen University)

14:20 Introduction to the ACROMASS project for the study of the charged components of the atmospheric cosmic radiation

The atmospheric muon flux has been measured by several experiments mainly between the 60s and 80s of the last century. Nonetheless the study of these particles is still of interest at least in two different fields of physics research. The first one is related to neutrino physics. A precise measurement of the parameters that characterize the phenomenon of oscillation between the three families of neutrinos known so far through the study of atmospheric neutrinos, requires an accurate estimation of the energy and angular spectra of these particles, that can be obtained in turn using detailed simulations calibrated with experimental measurements of atmospheric muons spectra. The second one is muon radiography, a geo-prospecting technique using atmospheric muons to produce radiographic representations of enormous volumes of materials and which requires the use of reliable simulations of the fluxes of atmospheric muons and their absorption inside materials.

Between the late 90s and the beginning of the 2000s, the INFN section of Florence and the Department of Physics of the University of Florence developed the ADAMO magnetic spectrometer, a test system for the development of the PAMELA satellite experiment. ADAMO was used in 2004 for a measurement of the inclusive momentum spectrum of cosmic rays at ground level at several zenith angles in the momentum interval between 100 MeV/c and 130 GeV/c. Results were presented at the 29th ICRC held in 2005 in Pune (India) [1].

The ACROMASS project, started in 2024, has been financed by INFN for the enhancement of the ADAMO spectrometer and to provide it with two auxiliary sub-detectors for particle identification (PID). The new apparatus will be used for measurements of atmospheric muons at different altitudes, latitudes and zenith angles in the momentum range between 100 MeV/c and 200 GeV/c and will also allow the study of the rarest charged components of cosmic rays at ground level.

References:
[1] L. Bonechi et al., "Development of the ADAMO detector: test with cosmic rays at different zenith angles", $29^{\mathrm{th}}$ International Cosmic Ray Conference Pune (2005) 9, 283–286

Speaker: Lorenzo Bonechi (Universita e INFN, Firenze (IT))

14:35 Physics potential of detecting solar neutrinos at JUNO

The Jiangmen Underground Neutrino Observatory (JUNO) [1] is a next-generation neutrino experiment located in China. Although the main goals of JUNO are to determine the neutrino mass ordering (NMO) and to perform sub-percent precision measurements of oscillation parameters with reactor antineutrinos, its physics program is broader and also includes studies on solar neutrinos [2, 3].

The JUNO central detector is an acrylic sphere 35.4 meters in diameter filled with 20 kt of liquid scintillator (LS). It is equipped with photomultiplier tubes (PMTs) of two types: 17612 20-inch PMTs and 25600 3-inch PMTs. The central detector is designed to provide an unprecedented energy resolution of 3% at 1 MeV. Although the target level of radiopurity of LS for performing the NMO analysis is set at $10^{-15}$ g/g of ${}^{238}$U and ${}^{232}$Th, solar neutrino analysis targets a level below $10^{-17}$ g/g.

The exceptional radiopurity of JUNO will enable the detection of neutrinos produced in the Sun in the pp chain — specifically ${}^8$B, ${}^7$Be, pep neutrinos — as well as neutrinos from the CNO cycle. The primary detection channel for solar neutrinos in JUNO is the neutrino-electron elastic scattering process. Depending on the radiopurity that JUNO will achieve, it will set stringent limits on the fluxes of ${}^7$Be, pep and CNO neutrinos, exceeding the limits of Borexino in a few years of data-taking.

In this talk, we will provide an overview of JUNO's solar neutrino physics prospects and its potential for detecting ${}^8$B, ${}^7$Be, pep, and CNO neutrinos.

[1] F. An et al., J. Phys. G 43 no.3, 030401 (2016).
[2] J. Zhao et al., Astrophys. J. 965 no.2, 122 (2024).
[3] A. Abusleme et al., JCAP 10, 022 (2023).

Speaker: Arsenii Gavrikov

13:20 → 14:50 SH: Solar modulation

13:20 Cosmic-ray modulation over the past 10 years observed with CALET on the International Space Station

The CALorimetric Electron Telescope (CALET) installed on the International Space Station (ISS) has been measuring high-energy cosmic rays (CRs) and gamma rays to understand the cosmic-ray acceleration and propagation. The CALET adopts a low-energy electron (LEE) trigger working at high geomagnetic latitudes that can measure the low-energy CR electrons in the energy region from 1 GeV to 10 GeV, in addition to the high energy (HE) trigger with an energy threshold of ~10 GeV. Using this LEE trigger, the CALET has observed the CR modulation of low-energy electrons and protons over nearly 10 years so far. In this work we report the CR modulation of low-energy electrons and protons observed by CALET since October 2015, including the solar minimum and the solar maximum of the 25th solar cycle. We especially focus on solar modulation during the solar maximum, discussing the variation of the electron and proton flux before and after the polarity reversal of the solar magnetic field, as well as the Forbush decrease.

Speaker: Shoko Miyake (National Institute of Technology (KOSEN), Gifu College)

13:35 Precision Measurement of Daily Proton and Helium Fluxes by the Alpha Magnetic Spectrometer

The precision measurement of the daily proton and helium fluxes with AMS during 13.5 years of operation will be presented. The period of observation covers solar cycle 24 from the ascending phase through its maximum going toward its minimum and solar cycle 25 through solar maximum. Detailed time variations of fluxes and ratio, including periodicities, will be presented. Remarkably, a hysteresis between the helium to proton flux ratio and the helium flux, below 2.4 GV, was observed before and after solar maximum in 2014 and solar minimum in 2020.

Speaker: Francesco Faldi (Universita e INFN, Perugia (IT))

13:50 Study of Forbush decrease in Cosmic-Ray Electron plus Positron events detected with DAMPE

The Forbush Decrease (FD) is characterized by a sharp decline followed by a gradual
recovery in the intensity of low-energy cosmic rays. This phenomenon is thought to
be caused by disruptions in the heliosphere caused by solar events, such as coronal
mass ejections (CMEs). The Dark Matter Particle Explorer (DAMPE), a
satellite-based experiment designed for detecting the cosmic radiation, including
electrons plus positrons, provides a unique platform to investigate FDs using these
particles, which have seldom been studied in detail before. In this study, the DAMPE electron plus positron data are analyzed with the aim of
investigating the properties of eight FDs since the mission start in December 2015
until 2024. An explanation on energy correlation with FD recover time is also
proposed. In order to address the impact of CMEs on cosmic ray propagation within
the solar system, the stochastic differential equation method is utilized. This approach
allows for an accurate modeling of the cosmic ray transport under disturbed
conditions. Finally, the model predictions are compared with observational data to
validate the results.

Speaker: Wenhao Li (Chinese Academy of Sciences (CN))

14:05 The Sun-Earth environment between the 24th and 25th solar cycles: observations and results from the High-Energy Particle Detector (HEPD-01) onboard the CSES-01 satellite

Galactic cosmic rays, as well as particles, accelerated to high energies either at the solar surface, corona, or in the interplanetary medium, are subject to various phenomena that can modify their energy distribution, intensity, and composition over different time scales. These effects are greater in the low-energy portion of the spectrum, and it is crucial to have instruments that can monitor energy intervals as low as possible and for a prolonged time. The China Seismo-Electromagnetic Satellite (CSES-01) mission – in particular the High-Energy Particle Detector (HEPD-01) – successfully continued studies of previous space-borne missions (ACE, AMS-02, EPHIN, ERNE, PAMELA) well into the 25th solar cycle. HEPD-01, launched in February 2018, is a light and compact payload suitable for measuring electrons (3-100 MeV), protons (30-250 MeV), and light nuclei (up to a few hundred MeV per nucleon) with a high energy resolution and a wide angular acceptance. The very good capabilities in particle detection and identification, together with the Sun-synchronous orbit, make this instrument very well suited for low-energy studies; moreover, being HEPD-01 just the first of a network of similar detectors that will be launched in the forthcoming years (HEPD-02 is set to launch this year), the evolution of particles inside the Sun-Earth environment is going to be fully investigated under many aspects. The latest results on the long-term solar modulation of protons and helium nuclei, the 27-day periodicity related to Corotating Interaction Regions, and impulsive phenomena like Solar Energetic Particle (SEP) events, geomagnetic storms, and Forbush decreases, will be presented.

Speaker: Matteo Martucci

14:20 Surprising Variation of Gamma Rays from the Sun over the Solar Cycle Revealed with Fermi

The steady-state gamma-ray emission from the Sun arises from interactions with Galactic cosmic rays and consists of two components: (1) a hadronic disk component and (2) a leptonic component peaking at the solar edge and extending into the heliosphere. Their flux is expected to vary with the 11-year solar cycle, peaking at solar minimum due to the higher cosmic-ray flux. However, no previous study has separately analyzed the temporal evolution of these components over multiple solar cycles.

This work focuses on investigating the flux variation of each component over 15 years of Fermi Large Area Telescope observations. We analyze their temporal evolution and compare the results with the sunspot number and Galactic cosmic-ray flux from AMS-02. We confirm that the disk component anticorrelates with solar activity and correlates with cosmic-ray protons, supporting the expected emission mechanism. The extended component also exhibits variability with the solar cycle, but its behavior suggests a more complex cosmic-ray transport and modulation in the inner heliosphere than previously assumed or hints at the presence of an additional, unknown gamma-ray or cosmic-ray source.

Speaker: Silvia RAINO' (Dipartimento di Fisica, Università di Bari & INFN - Bari)

14:35 Study the relationship between Galactic Cosmic Rays’ 27 day recurrent variation and Corotating Interaction Region

The development of advanced space-based cosmic ray observation experiments (such as AMS, PAMELA, and DAMPE) have provided precise data, offering new opportunities for the study of cosmic ray solar modulation. During 2007-2008, as the period of longest-live coronal holes and corresponding variation in all heliospheric characteristics, the pronounced 27-day wave in the GCR intensity had been observed by PAMELA. In 2016, the AMS experiment observed significant 27-day periodic variations of cosmic ray protons, helium nuclei, and electrons. To investigate the theoretical mechanism and deepen our understanding of this 27-day periodic variations, we employed a magnetohydrodynamic (MHD) numerical model to simulate the solar wind environment containing corotating interaction regions (CIRs). We then coupled this model with a cosmic ray propagation model. Using this coupled framework, we simulated the modulation processes of protons, helium nuclei and electrons with different rigidities under the influence of CIRs. The simulation results reveal that: Protons, helium and electrons are affected by CIRs, with their fluxes decreasing and then recovering. The modulation strength of CIRs on cosmic rays, is decreasing as rigidity increases. At higher rigidities, this modulation can be approximated by a power-law shape. The manner in which protons and helium-4 responds to the presence of a CIR is similar, while electrons behaves differently, indicating a clear charge-sign dependent effect as well.

Speaker: Xi Luo (Shandong Institute of Advanced Technology)

14:50 → 15:20 Coffee

15:20 → 16:35 CRD: experimental results: isotopes

15:20 Precision Measurement of Cosmic Ray Deuterons with Alpha Magnetic Spectrometer

Precision measurements by the Alpha Magnetic Spectrometer (AMS) on the International Space Station of the deuteron ($D$) flux are presented. The measurements are based on 21 million $D$ nuclei in the rigidity range from 1.9 to 21 GV collected from May 2011 to April 2021. We observe that over the entire rigidity range the $D$ flux exhibits nearly identical time variations with the $p$, $^3$He, and $^4$He fluxes. Above 4.5 GV, the $D$/$^4$He flux ratio is time independent and its rigidity dependence is well described by a single power law $\propto R^\Delta$ with Δ$_{D/^4\text{He}} =−0.108±0.005$. This is in contrast with the $^3$He/$^4$He flux ratio for which we find Δ$_{^3\text{He}/^4\text{He}} =−0.289±0.003$. Above ∼13  GV we find a nearly identical rigidity dependence of the $D$ and $p$ fluxes with a $D/p$ flux ratio of $0.027 ±0.001$. These unexpected observations indicate that cosmic deuterons have a sizable primarylike component. With a method independent of cosmic ray propagation, we obtain the primary component of the $D$ flux equal to $9.4 ±0.5\%$ of the $^4$He flux and the secondary component of the $D$ flux equal to $58 ±5\%$ of the $^3$He flux.

Speaker: Francisco Hernandez Nicolas (CIEMAT - Centro de Investigaciones Energéticas Medioambientales y Tec. (ES))

15:35 Voyager 1 Observations of Galactic Cosmic Ray Isotopes in the Very Local Interstellar Medium: Evidence for Primary 2H and B

We present the first measurements of the energy spectra of the isotopes of galactic cosmic rays (GCRs) with nuclear charge $Z=1-14$ in the very local interstellar medium (VLISM). We also update our previously published energy spectra of GCR elements in the VLISM from $Z=1-28$ (Cummings et al. 2016) for the new longer time period of observations, 1/1/2013 through 12/31/2021. The observations are from the Cosmic Ray Subsystem (CRS) (Stone et al. 1977) on the Voyager 1 (V1) spacecraft and cover the $Z$-dependent energy range from $\sim$$3-661$ MeV/nucleon. The data are fit to eight models using the GCR propagation code GALPROP, and provide a new set of GCR elemental source abundances. The models all have injection spectra as power laws in rigidity, all with the same power-law index, and fit exclusively to the V1 data. The eight models differ in the relative abundances and by having two options for production cross sections and four options for total fragmentation cross sections. The VLISM energy spectra generated by all eight models agree reasonably well with the observed VLISM energy spectra for the elements with $Z$ from $1-28$ and with the isotopes with $Z$ from $1-14$. However, in all models it was necessary to add contributions from a primary source of $^2$H and B.

Speaker: Igor Moskalenko

15:50 Cosmic-Ray Beryllium Isotopes with the Alpha Magnetic Spectrometer

Beryllium nuclei in cosmic rays are expected to be secondaries produced by the fragmentation of primary cosmic rays during their propagation in the Galaxy. Therefore, their fluxes contain essential information on cosmic ray propagation and sources. Secondary-to-primary flux ratios provide measurements of the material traversed by cosmic rays in their journey through the Galaxy. The 10Be/9Be ratio measures the cosmic ray propagation volume in the Galaxy. Current measurements of the 10Be/9Be ratios are limited to energies below 2 GeV/n, and are affected by large uncertainties. Individual fluxes of 7Be, 9Be and 10Be, have only been measured below 0.4 GeV/n. In this contribution, we present the measurement of the 7Be, 9Be, 10Be fluxes and their ratios, in the uncharted energy region ranging from 0.4 GeV/n to 12 GeV/n based on data collected by AMS during its first 12.5 years of operation on the International Space Station.

Speaker: Weiwei Xu (Shandong University (CN))

16:05 Isotopic composition of cosmic rays with the HELIX balloon project

Clock isotopes such as beryllium-10 provide a unique Galactic cosmic ray lifetime measurement related to the size of the propagation halo in the Milky Way. There have yet to be high-precision measurements of beryllium-10 above 2 GeV/n. The High Energy Light Isotope eXperiment (HELIX), a balloon-borne magnet spectrometer, directly measures a cosmic ray’s charge, magnetic rigidity, and velocity to identify the isotopes of beryllium and other light nuclei. The HELIX program will improve the statistics and extend the resolved measurements of beryllium isotopes to as high as 10 GeV/n. The magnetic rigidity is measured with a high-precision drift chamber tracker in a 1 Tesla magnetic field generated by a pair of superconducting coils. Time-of-flight scintillator paddles are used for charge measurements and velocity at lower energies, whereas at higher energies velocity is measured with an aerogel-based ring-imaging Cherenkov detector. During the boreal spring of 2024, HELIX had an engineering flight from Esrange, Sweden. This contribution presents an overview of the payload, flight, and the status of ongoing analysis efforts.

Speaker: Dr Keith McBride (University of Chicago)

16:20 Cosmic ray ionisation rate and Beryllium-10 modelling with inhomogeneous interstellar medium and time-dependent cosmic ray sources

We use the GALPROP cosmic ray (CR) propagation and associated diffuse emissions framework to investigate the CR-induced ionisation rate and distribution of radioactive CR species in the presence of an inhomogeneous interstellar gas distribution and stochastic, finite lifetime CR sources. The interstellar gas model is based on recent reconstructions of the gas survey line intensity data and stellar extinction (for interstellar dust). It exhibits a large dynamic range of gas densities, and traces filaments, shells, and features associated with the Local Bubble at sub-10 parsec resolution. Compared to CR solutions using smooth spatial gas distributions and steady-state CR injection, there is a significant variability in the ionisation rate spatial distribution. Moreover, the radioactive CR species differ, compared to the homogeneous/steady-state case. Implications for studies of interstellar chemistry, CR propagation models, and other relevant topics will be discussed.

Speaker: Troy Porter

15:20 → 16:50 CRI: extensive air shower

15:20 Measurement of the Inelastic Proton-Proton Cross-Section at $\sqrt{s} \geq 40$ TeV Using the Hybrid Data of the Pierre Auger Observatory

Measuring proton-proton interaction cross-sections at center-of-mass energies above 40 TeV remains a significant challenge in particle physics. The Pierre Auger Observatory provides a unique opportunity to study the interactions at the highest energies through the distribution of the depth of maximum shower development ($X_\mathrm{max}$) observed by its Fluorescence Detector. In previous studies, the determination of the interaction cross-section at ultrahigh energies has relied on the assumption that the tail of the $X_\mathrm{max}$ distribution is proton-dominated, which restricts the analysis to a limited energy range below the ankle and introduces related systematic uncertainties. In this contribution, we apply a novel method for the simultaneous estimation of the proton-proton interaction cross-section and the primary cosmic-ray mass composition to data from the Pierre Auger Observatory, avoiding assumptions about one quantity to infer the other and thus improving the accuracy and robustness of our analysis. In addition, a systematic shift in the $X_\mathrm{max}$ scale is fitted to account for both experimental uncertainties and theoretical constraints on the modeling of particle interactions. The obtained results are consistent with previous analyses and provide additional constraints on hadronic interaction models. The measured proton-proton inelastic cross-section at ultra-high energies agrees well with extrapolations of accelerator data. The inferred cosmic-ray composition and the $X_\mathrm{max}$ scale shift are also compatible with previous estimates.

Speaker: Dr Olena Tkachenko (Institute of Physics of the Czech Academy of Sciences)

15:35 Update on testing of air-shower modelling using combined data of the Pierre Auger Observatory and phenomenological consequences

The combined data of fluorescence and surface detectors of the Pierre Auger Observatory has recently provided the strongest constraints on the validity of predictions from current models of hadronic interactions [Phys. Rev. D 109 (2024) 102001]. The unmodified predictions of these models on the depth of shower maximum (Xmax) and the hadronic part of the ground signal are unable to accurately describe the measured data at a level of more than 5 sigma in the energy range 3-10 EeV. This inconsistency has been shown to originate not only from the predicted amount of muons at the ground level, but also from the predicted scale of Xmax, which must be adjusted to better match the observed data. The resulting deeper Xmax scales of the models imply a heavier mass composition to be interpreted from the Xmax measurements.

We will show the results of the test with an updated data set of the Pierre Auger Observatory, studying also the energy evolution of the fitted modification parameters and new versions of the models of hadronic interactions. Additionally, we will discuss the phenomenological consequences of the deeper Xmax scale of models on the interpretation of the features of the energy spectrum and the muon problem in air-shower modelling.

Speaker: Dr Jakub Vicha (Institute of Physics of the Czech Academy of Sciences)

15:50 Constraining Hadronic Interaction Models with UHECR Observables

In the physics of Ultra-High Energy Cosmic Rays (UHECR), there is a well-established disagreement between the predictions of the last generation of hadronic interaction models and the measurement of the number of muons. Lately, there have also been hints of a disagreement on the scale of shower maxima. The MOdified Characteristics of Hadronic Interactions (MOCHI) is a simulation framework created for the purpose of exploration of plausible changes to final states of hadronic interactions. We focus on the observables of $X_{\text{max}}$ and $R_{\mu}$ measured at the Pierre Auger Observatory and quantify the changes to cross-section, elasticity, and multiplicity of the hadronic interactions that describe the apparent shifts in the scales of the observables. We systematically explore the implications. In particular, we show that such modifications are in conflict with other data measured at Pierre Auger Observatory. Finally, we take a cursory look at the newest generation of hadronic interaction models and describe where they lie in the space of parametric changes explored by MOCHI.

Speaker: Jiri Blazek (FZU)

16:05 Investigation of Muon Excess from Initial Hadronic Interactions in Cosmic Air Showers with a One-ton Scintillator Detector at CJPL

Over the past decade, ground-based array experiments have observed a notable muon deficit when simulating extensive air showers (EAS) induced by high-energy cosmic rays, compared to experimental measurements. This discrepancy is referred to as the muon puzzle. In this report, we present the first investigation on this topic at the China Jinping Underground Laboratory (CJPL), which, with its 2400-m vertical rock overburden, limits muons to energies above 3 TeV, with an average primary cosmic-ray energy of 0.4 PeV. This provides a clean window for studying the initial EAS processes. The data, collected over 1178 live days from the 1-ton prototype of the Jinping Neutrino Experiment, along with a GEANT4-based flux simulation framework, are used for comparison in this work. Our results show that the measured muon flux is approximately 30% higher than predicted, with a 2$\sigma$ significance (3$\sigma$ excluding model-related uncertainties), and no significant angular dependence is observed. These findings highlight the potential for future high-energy cosmic-ray research in deep underground environments.

Speaker: Xinshun Zhang (Tsinghua University)

16:20 Characterizing the neutron component of extensive air showers with the Surface-Scintillator Detectors of AugerPrime

Neutrons are the only neutral hadrons that remain stable over the timescale of an air-shower development.
Their energy is lost only through hadronic interactions and quasi-elastic scattering, which results in their high abundance at the ground.
The signals from the electromagnetic and muonic components in scintillation detectors typically span only a few microseconds.
In contrast, the neutrons can result in delayed pulses in scintillation detectors up to and beyond several milliseconds after the passage of the shower front.
Selection of an appropriate time window allows us to isolate and characterize the neutron component of air showers, which may provide a new, direct method to probe hadronic interactions during shower development.
We report the measurement of a neutron component at ultra-high energies using the Surface-Scintillator Detectors (SSD) from the AugerPrime upgrade of the Pierre Auger Observatory.
We provide a first look at the pulse-amplitude spectrum together with our measured rate and lateral distribution of the neutron component.

Speaker: Tobias Schulz

16:35 Multimuon events from cosmic rays in ALICE

ALICE experiment at CERN Large Hadron Collider, located 52 meters underground, carried out a cosmic data-taking campaign in the period 2015-2018 corresponding to 62.5 days of live time. In this work the analysis of these data is limited to multimuon events defined as events with more than four detected muons. In particular the muon multiplicity distribution (MMD) is studied in the low-intermediate multiplicity ($4100$) is measured. The results are compared with the Monte Carlo simulations using three of the main hadronic interaction models describing the air shower development in the atmosphere: QGSJET-II-04, EPOS-LHC, and SIBYLL 2.3d. Two extreme compositions of primary cosmic rays were simulated: pure proton, representing the lightest possible composition, and pure iron, representing an extremely heavy composition. Although the models have difficulty in describing precisely the composition trend of cosmic rays, QGSJET-II-04 is the only model that reproduces reasonably well the MMD and the rate of the HMM events assuming a heavy composition for the entire energy range studied.

Speaker: Bruno Alessandro (Universita e INFN Torino (IT))

15:20 → 16:50 CRI: radio detection

15:20 Search for cosmic rays in GRANDProto300

GRANDProto300 (GP300) is a prototype array of the GRAND experiment, designed to validate the technique of autonomous radio-detection of astroparticles by detecting cosmic rays with energies between $10^{17}$-$10^{18.5}$ eV. This observation will further enable the study of the Galactic-to-extragalactic source transition region. Since November 2024, 46 out of 300 antennas have been operational and collecting data stably. We present our cosmic ray search pipeline, which involves several filtering steps: (1) coincidence search for signals triggering multiple antennas within a time window, (2) directional reconstruction of events, (3) exclusion of clustered (in time and space) noise events, (4) spectral analysis to remove noise featuring frequency peaks, (5) polarization cut, and (6) selection based on the size of the footprint. The efficiency of the pipeline is evaluated and applied to the first batch of data, yielding a set of candidate cosmic-ray events, which we present.

Speaker: Jolan LAVOISIER (CNRS - Institut d'Astrophysique de Paris)

15:35 Determination of the energy scale of cosmic ray measurements using the Auger Engineering Radio Array

The accurate determination of the absolute energy scale in cosmic ray
measurements is both a challenging and fundamentally important task. In this contribution, we present how measurements of radio pulses from extensive air showers with the Auger Engineering Radio Array, combined with per-event simulations of radio emission using the CoREAS extension of CORSIKA, allow us to determine the energy scale of cosmic rays between 3 \times 10^{17} eV and several 10^{18} eV.
Our analysis accounts for many factors, each of them controlled on the 5%
level or better. The absolute calibration of the antennas and the entire
analog signal chain builds on a Galactic calibration in combination with a detailed understanding of the antenna gain patterns. Additional key elements include compensation for temperature-dependent signal amplification, continuous detector health monitoring, an active veto for thunderstorm conditions, an unbiased event reconstruction, and per-event atmospheric modeling in the simulations. The analysis benefits from a high-statistics dataset of over 800 measured cosmic-ray showers.
We describe our analysis method, perform multiple cross-checks, and evaluate systematic uncertainties. Finally, we determine the energy scale of cosmic rays using the Auger Engineering Radio Array and compare it to the energy scale of the Pierre Auger Observatory, as established by the Fluorescence Detector.

Speaker: Tim Huege

15:50 High energy cosmic ray detections with the standalone radio trigger system at the Owens Valley Radio Observatory Long Wavelength Array

Radio observations of cosmic ray air showers can characterize cosmic ray mass composition, via precise Xmax measurements, at the energies of the likely shift from Galactic to extragalactic sources. Advantages over other methods include lower cost instrumentation and the ability to operate in a range of weather conditions. However, detecting cosmic rays via their radio emission alone amid radio frequency interference (RFI), without reference to an alternate particle detector, is a significant challenge. The Owens Valley Radio Observatory Long Wavelength Array (OVRO-LWA) cosmic ray detection system uses a multistage RFI rejection process including FPGA and CPU processing to address this challenge and operate in the presence of RFI. The OVRO-LWA is a multi-use array of 352 dual-polarization dipole antennas operating at ~30—80 MHz. The array recently completed a major upgrade, including the addition of the cosmic ray detection system, which operates simultaneously with the other radio astronomy observing modes. Detections of cosmic ray candidates began in 2024. The dense antenna spacing of the OVRO-LWA offers the opportunity for testing and developing new Xmax reconstruction techniques, such as interferometric reconstruction. This presentation will describe the cosmic ray detection system, present the sample of cosmic ray candidates, and discuss plans for the future.

Speaker: Kathryn Plant (Jet Propulsion Laboratory, Caltech)

16:05 Systematic uncertainties in radio emission of extensive air showers: A comparison of CoREAS and ZHAireS

Radio detection of extensive air showers induced by ultra-high energy cosmic rays has significantly advanced in recent decades. Observables such as shower energy and depth of maximum development are largely derived by comparing experimental data with Monte Carlo simulations, making it essential to assess the systematic uncertainties associated with the simulation models. In this work, we present a comprehensive comparison between CoREAS and ZHAireS, the two most widely used simulation codes for modeling radio emission from air showers. We simulated showers initiated by different primary particles, with various arrival directions and geomagnetic conditions, ensuring similar input parameters and the same altitude-dependent atmospheric refractive index in both cases. We find a good agreement between CoREAS and ZHAireS, with differences in the electric field components, across the MHz to hundreds of MHz frequency range, that are typically below below $5\%$ in the Cherenkov cone, the region where the electric field is stronger, and below $10\%$ elsewhere. These differences result in uncertainties of a few $\%$ on the energy released in the form of radio waves, and a few $\mathrm{g/cm^2}$ in depth of shower maximum, indicating small systematic effects in the reconstruction due to the differences between the models.

Speaker: Jaime Alvarez-Muniz (Universidad de Santiago de Compostela)

16:20 Energy estimation of atmosphere-skimming cosmic ray events using the radio technique

Cosmic rays can induce extensive air showers whose development takes place entirely inside the atmosphere, without reaching the ground. These atmosphere-skimming events have been detected with balloon-borne experiments such as ANITA and EUSO-SPB2. In this work, we evaluate the possibility of estimating the energy of an atmosphere-skimming cosmic ray shower through measurements of radio pulses. We report on the performance of an energy reconstruction method which adapts existing algorithms to the peculiar characteristics of atmosphere-skimming events, and study its accuracy for different event geometries, and in different scenarios of angular resolution and signal-to-noise ratio.

Speaker: Sergio Cabana-Freire (IGFAE - Universidade de Santiago de Compostela)

16:35 On the performance of air shower reconstruction with the SKA-Low radio telescope

The Square Kilometre Array (SKA) is a radio telescope currently under construction in South Africa and Australia.
Its low-frequency part (50-350 MHz), located in Australia, features nearly 60,000 antennas in a core region of about 1 km diameter.
With such an extreme antenna density, surpassing e.g. LOFAR by two orders of magnitude, this observatory is well equipped to make the most precise radio measurements of individual air showers.
A decade of experience with LOFAR serves as a foundation for a next major step in reconstruction precision. We present a simulation of the reconstruction capabilities, using CoREAS-simulated showers, a realistic model of the antennas, and of the Galactic noise background.
We apply the method used at LOFAR for reconstruction the depth of shower maximum $X_{\mathrm{max}}$, measuring the energy fluence of the radio pulse in each antenna and using an ensemble of simulated showers to fit to the data. We consider the use of beamforming within this method, combining groups of nearby antennas to boost the signal-to-noise ratio.
The reconstruction precision that follows is about 6 to 8 g/cm$^2$ over a primary energy range of $10^{16}$ to $10^{18}$ eV, with a minimal bias from the reconstruction process.
This sets a baseline to what can be achieved, both in energy range extension downward as in reconstruction precision, from methods that haven proven robust in practice.
Further significant progress is expected, as new methods are being developed that measure the longitudinal shower profile in more detail than just its $X_{\mathrm{max}}$.
We also discuss expected event rates given reasonable technical limitations, relating this to suitable numbers for a mass composition analysis in narrow energy bins.

Speaker: Dr Arthur Corstanje (Vrije Universiteit Brussel)

15:20 → 16:50 GA: AGNs

15:20 Insights into M87's Multi-Wavelength Properties during the 2018 EHT Campaign, Featuring a Gamma-Ray Flaring Episode

Simultaneously with the Event Horizon Telescope (EHT) imaging the black-hole shadow of M87 for the first time in 2017, an extensive multi-wavelength (MWL) observational campaign was conducted involving ground and space-based instruments covering fifteen decades of energy ranging from radio to very high-energy gamma rays. During this first campaign, the innermost knot HST-1 and the core of M87 were observed to be in historically low states. In 2018, a similar MWL observational campaign was carried out, during which we detected a brief gamma-ray flaring episode - the first gamma-ray flare observed in M87 in over a decade. We compare the results of the 2018 MWL campaign with the quiescent state observed the previous year along with a contemporaneous broad-band spectral energy distribution and MWL light curves. Additionally, heuristic modelling provides new insights into investigating the origin of the gamma-ray emission from M87.

Speaker: Alexander Hahn

15:35 The origin of the very-high-energy radiation of Centaurus A

As the closest known active galactic nucleus, Centaurus A provides a rich environment for astrophysical exploration, being detected from radio to gamma rays. Recently, very-high-energy gamma rays have been measured by the HESS observatory. The signal is associated with the jet, revealing the presence of relativistic electrons. However, the underlying acceleration mechanism remains uncertain. Several works have proposed that jet substructures, known as knots, may act as efficient particle accelerators. In this work we model the particle acceleration in the knots, assuming they originate from the interactions between the jet and powerful stellar winds. The knots are modeled using relativistic hydrodynamics simulations using the PLUTO code. It is assumed that the shock injects relativistic electrons whose maximum energy depends on the radiation fields of the galaxy. The spectral index is found based on the radio and X-ray observed data, assuming a synchrotron origin. Inverse Compton scattering of the same electron population produces the very-high-energy gamma rays in this model. Our findings suggest that electrons accelerated at the knots are responsible for the gamma-ray spectrum detected in the very-high-energy band. The possibility of knots as ultra-high-energy cosmic ray accelerators is also explored.

Speaker: Cainã de Oliveira (University of São Paulo)

15:50 Studies on the VHE spectrum of the radio galaxy M87 observed by HAWC

Suggestion: The radio galaxy M87 has been detected at energies above 1 TeV with a significance exceeding 5$\sigma$ using nearly 10 years of data from the HAWC observatory. To gain further insight into the nature of this emission, we model it with different physical scenarios, ranging from a simple Synchrotron Self-Compton leptonic model to hadronic models. We constrain the physical parameter space under the different spectral models taking into account the systematic uncertainties arising from the assumed extragalactic background light (EBL) attenuation models.

Speaker: Ms Mabel Osorio Archila (Universidad Nacional Autónoma de México, Instituto de Astronomía, A. P. 70-264, 04510, CDMX, México)

16:05 VERITAS Discovery and Multi-wavelength Observations of 1ES 1028+511

Very high energy (>200 GeV) gamma-ray emission was discovered from the blazar 1ES 1028+511 located at redshift z= 0.361 as part of the VERITAS AGN Discovery Program. It is classified as an extreme high-frequency-peaked BL Lac object (EHBL) and is potentially an interesting object for multi-messenger studies. This EHBL was selected for observation because of its bright X-ray emission and its hard Fermi-LAT spectrum; its photon index is 1.64±0.05 in the 4th Fermi-LAT Catalog. The ~49 hours of good-quality VERITAS observations enable a measurement of the VHE spectrum up to nearly 1 TeV, which allow a strong probe of features in the VHE spectrum existing due to the absorption of photons on the Extragalactic Background Light. The broadband spectral energy distribution (SED) of 1ES 1028+511, including both SED peaks, will be presented.

Speaker: Dr Jodi Christiansen (California Polytechnic State University San Luis Obispo)

16:20 long-term observation of the blazars Mrk 421by LHAASO

The well-known blazars, Markarian 421 (Mrk 421) has been detected with high significance by LHAASO. Since the observation of gamma radiation from blazars provides insights into the physical processes occurring in their relativistic jets making it crucial to study their broad-band spectral energy distribution (SED). For this purpose, contemporaneous data in the gamma-ray band along with X-ray data, as well as radio to ultraviolet (UV) range data, are all used to construct time-averaged SEDs. In this work, the time-averaged spectral analysis results and their relative model outcomes will be presented.

Speaker: Ran Wang (Shandong University, China)

16:35 SED evolution modeling of Mrk421 during its most violent year: insights from a stochastic acceleration model

Blazars are highly variable sources and show variability down to minute time scales. The current generation of Imaging Atmospheric Cherenkov Telescopes like MAGIC are able to probe the spectra of the brightest blazars at short time scales, especially in their flaring states. In this work, we characterize the variability and daily Spectral Energy Distribution (SED) evolution of the archetypal TeV blazar Mrk421 using simultaneous MAGIC very high energy (VHE band, >100 GeV) and multi-wavelength (MWL) observations from radio all the way up to gamma ray bands during the Nov 2009 to June 2010 campaign.

Mrk421 displayed its strongest flare ever observed in February 2010 when VERITAS measured VHE flux of ~15 Crab units above 200 GeV. VLBA data unveils contemporaneous ejections of radio features for the first time for Mrk421. The variability and MWL cross-correlations were analyzed along with the temporal evolution of the daily SEDs to gain insights into the emission processes of this flare that exhibits unprecedented characteristics for the source. We model the source with a physically motivated single zone leptonic population and study the phenomenology and spectral evolution in the context of a stochastic acceleration scheme.

Speaker: Jayant Abhir (ETH Zurich)

15:20 → 16:50 GA: space experiments

15:20 The Compton Spectrometer and Imager

The Compton Spectrometer and Imager (COSI) is a NASA Small Explorer class space-based mission scheduled to launch in 2027. COSI will function as a wide field imager, spectrometer, and polarimeter, and it will be sensitive to photons between 0.2 - 5 MeV. The four primary science goals of COSI are 1) uncover the origin of Galactic positrons, 2) reveal Galactic element formation, 3) gain insight into extreme environment with polarization, and 4) probe the physics of multimessenger events. In this presentation, we will provide an update on the COSI mission, present an overview of the development status of its hardware and calibration, and report on the latest updates in software development.

Speaker: Savitri Gallego

15:35 Development status of the SMILE-3 balloon experiment

MeV gamma-ray astronomy remains relatively underexplored, despite
extensive worldwide efforts to investigate this crucial energy range.
To address this challenge, we have demonstrated the high-performance
capabilities of an electron-tracking Compton camera (ETCC) during the
Sub-MeV/MeV gamma-ray Imaging Loaded-on-balloon Experiment (SMILE)
missions. The ETCC employs a gaseous time-projection chamber (TPC) as
the primary scatterer, surrounded by pixelated scintillator arrays
(PSAs) that function as absorbers. The gas TPC measures the momentum
vector of the recoil electron, while the PSAs simultaneously determine
the energy of the scattered gamma ray. This capability enables a
bijective reconstruction of both the direction and energy of the
incident gamma ray, which enhances the sensitivity compared to
classical Compton reconstruction that constrain the incident direction
only by a circular region. The SMILE-2+ experiment, which consisted of
a 26-hour balloon flight over Australia, successfully detected the
Crab Nebula and Galactic diffuse emissions around the Galactic Center
at a significance level exceeding 4\sigma. Following this achievement, we
have initiated the successor project, SMILE-3, to enable a more
detailed investigation of diffuse emissions. The detector design has
been upgraded to achieve a larger effective area and a wider dynamic
range, thereby increasing photon collection power. The first flight for
SMILE-3 is currently planned for early 2027. In this paper, we present
an overview of the SMILE-3 experiment and report the current status of
our R&D efforts.

Speaker: Takeshi Nakamori

15:50 The newASTROGAM MeV to GeV Gamma-ray Observatory

newASTROGAM is a breakthrough mission concept for the study of the non-thermal Universe from space with gamma rays in the energy range from 100 keV to 3 GeV. It is based on an advanced space-proven detector technology, which will achieve unprecedented sensitivity, angular and energy resolution combined with polarimetric capability. Since the MeV gamma-ray energy range is the most under-explored electromagnetic window to the Universe, a mission in this energy range can address fundamental astrophysics questions connected to the physics of compact objects and merger events, jets and their environments, supernovae and the origin of the elements, potentially constrain the nature of dark matter and many more. newASTROGAM provides in addition unique continuation of sensitivity into the GeV energy range and to transients, and will detect and follow-up many of the key sources of multi-messenger astronomy in the 2040s.

newASTROGAM consists of a Silicon tracker followed by a crystal calorimeter, which are both wrapped into an anti-coincidence detector to reject chaged cosmic rays. Such a mission can detect gamma rays via Compton scattering interactions or the production of pairs of electrons and positrons. This mission concept will be proposed to the ESA call for medium-class mission ideas (M8). In this talk we will review the main science cases for an MeV to GeV general purpose observatory and introduce the mission concept.

Speaker: Prof. David Berge (DESY & Humboldt-University Berlin)

16:05 The Galactic Annihilation Line Explorer (GALE): Balloon-borne Mission to study Galactic 511-keV annihilation emission

The Galactic Annihilation Line Explorer (GALE) mission will address a long-outstanding question in our understanding of the sources of Galactic positrons: whether they are produced by unresolved astrophysical sources or created via diffuse processes, possibly due to dark matter decay and/or annihilation. The problem of Galactic positrons that produce 511-keV gamma-ray emission from the Galactic plane and Galactic Center has existed for years and is well-defined with the measurements by INTEGRAL/SPI. GALE is designed to achieve the needed angular resolution (fraction of a degree) and point source sensitivity (< 10^-4 ph/cm^2/s) required to understand the 511-keV emission structure in the Galactic Center. The GALE instrument combines a coded-aperture mask (CAM) with a cadmium-zinc-telluride imaging calorimeter to form a combined CAM/Compton telescope. The Wallops Arc-Second Pointer (WASP) support system will be used to achieve the precise telescope pointing control to the GC and for the coded aperture imaging proper operation. In this talk, the science goals, GALE instrument design, anticipated performance and mission will be discussed.

Speaker: Alexander Moiseev

16:20 Status of AMEGO-X, the All-sky Medium Energy Gamma-Ray Observatory eXplorer

MeV gamma-ray observations are important to deepen our understanding of the physics of high energy phenomena such as active galactic nuclei and gamma-ray bursts. Particularly an all-sky MeV gamma-ray facility with a good localization accuracy of about 1 degree can significantly increase the number of follow-up observations of transient events, increasing opportunities for multi-messenger astronomy. Therefore, we propose the AMEGO-X project (PI: R. Caputo (GSFC/NASA)) as a future all-sky MeV gamma-ray satellite. Its gamma-ray detector has an order of magnitude better sensitivity than previous telescopes in the energy range 100 keV to 1 GeV with the localization accuracy of 1 degree (90% C.L. radius) for transient sources. Although our proposal for AMEGO-X was not selected for the 2021 NASA MIDEX Announcement of Opportunity, we have kept working to enhance the feasibility of the project for the next opportunity. We have made significant progress on the development and evaluation of a novel silicon pixel detector, AstroPix, which serves as the primary sensor for AMEGO-X. We plan to test AstroPix in space environment using a sounding rocket scheduled for 2026. In addition, the prototype detector of AMEGO-X called ComPair-2, consisting of a 10-layer AstroPix silicon tracker and a CsI calorimeter array, was selected as a NASA APRA funded project (PI: R. Caputo). We commenced the development of the ComPair-2 detector system with a new composite structure design and initial tests of the first prototype tracker layer is under way. In this contribution, we report on the AMEGO-X project, its scientific objectives, the development status of both AstroPix and ComPair-2, and future prospects.

Speaker: Yusuke Suda (Hiroshima University)

16:35 Imaging MeV Gamma-ray Lines with Advanced Image Reconstruction Framework for COSI

The Compton Spectrometer and Imager (COSI), scheduled for launch in 2027, will improve sensitivity for MeV gamma-ray line observations by an order of magnitude, opening new windows to study cosmic nucleosynthesis. Primary targets include the 511 keV emission from positron annihilation, $^{26}$Al from stellar nucleosynthesis, and $^{44}$Ti from supernova remnants. With its wide field of view, COSI will provide all-sky images for these lines with the best sensitivity ever. However, image reconstruction in this energy band presents unique challenges: an event of Compton telescopes constrains the gamma-ray direction to a circle in the sky rather than a point, necessitating a statistical approach to recover the gamma-ray source distribution. Also, the complex background environment requires careful treatment for reliable source detection.

We present an advanced image reconstruction framework for MeV gamma-ray observations. Our approach introduces a modified Richardson-Lucy algorithm with Bayesian priors optimized to address these challenges. The framework flexibly incorporates prior distributions, such as the sparseness and smoothness of an image, while simultaneously fitting the background components. We evaluate the method using simulated three-month COSI observations of key nuclear lines ($^{44}$Ti at 1.157 MeV, $^{26}$Al at 1.809 MeV, and positron annihilation at 0.511 MeV). Our results show successful suppression of artifacts in point source reconstructions while preserving extended emission features, demonstrating improved image quality and sensitivity compared to conventional techniques. This work represents an important step toward advancing our understanding of nucleosynthesis, positron annihilation, and other high-energy phenomena with future MeV gamma-ray line observations.

Speaker: Dr Hiroki Yoneda

15:20 → 16:50 NU: experimental & next generation

15:20 Search for Diffuse Supernova Neutrino Background in Super-Kamiokande Gadolinium experiment

Observation of Diffuse Supernova-Neutrino Background (DSNB) gives us a new insight into star formation history. The SuperKamiokande (SK) experiment aims to make the first discovery of this flux.
Since 2020, the SK detector has been updated by loading gadolinium (Gd) as a new experimental phase, ‘SK-Gd.’
In the SK-Gd experiment, event selection with delayed coincidence using neutron capture signal, such as inverse beta decay of electron antineutrinos, is improved thanks to high cross-section and high energy gamma-ray emission of thermal neutron capture on Gd.
In July 2022, the observation with 0.01% Gd mass concentration was completed, and currently, an updated phase with 0.03% mass concentration is in operation.
We report the result of a search for the DSNB flux in SK-Gd with a 22.5×956 kton×day exposure. Finally, prospects for the DSNB search in SK-Gd are discussed.

Speaker: Masayuki Harada (ICRR, The University of Tokyo)

15:35 Astrophysical neutrino search in KamLAND

Neutrinos emitted from past supernovae are known as Supernova Relic Neutrinos (SRNs). Since the prediction of SRN flux relies on astrophysical inputs such as the supernova rate and cosmic star formation history, the detection of SRNs is expected to provide complementary information to refine these models. KamLAND, a 1-kiloton liquid scintillator, detects electron antineutrinos via inverse beta decay using delayed-coincidence method. Due to its high sensitivity in the $\sim 10\,$MeV energy region, KamLAND has a significant advantage in SRN observation. The dominant background in this energy region arises from neutral current interaction of atmospheric neutrinos. To reduce this background, we are developing a background reduction method using a deep neural network, which exploits differences in the spatiotemporal dispersion of hit information in the photomultiplier tubes. In this presentation, we report on the progress of this background reduction method for SRN search. Additionally, we present the latest status of pre-supernova neutrino alarm system and the ongoing search of neutrinos from primordial black holes, a dark matter candidate and a possible neutrino emitter.

Speaker: Minori Eizuka (RCNS, Tohoku Univ.)

15:50 The IceCube-Gen2 project

IceCube-Gen2 is a next-generation neutrino observatory, building on IceCube's discovery of cosmic neutrinos. It will increase detection rates by an order of magnitude, probe fainter sources, and extend energy sensitivity to EeV scales with a new radio array. IceCube-Gen2 will explore cosmic particle acceleration, the origins of the highest-energy particles, and fundamental physics, all while complementing next-generation electromagnetic and gravitational wave observatories. In this talk I will provide an overview of the project.

Speaker: Marek Kowalski (DESY)

16:05 Prospects for GeV Neutrino Transient Searches with the IceCube Upgrade

The recent detection of TeV neutrino sources by the IceCube Neutrino Observatory demonstrates the detector's advanced capabilities in detecting high-energy astrophysical neutrinos. At lower energies, down to the GeV range, a variety of transient phenomena, such as novae, supernovae, and gamma-ray bursts, are expected to emit neutrinos. Observations of these neutrinos can provide unique insights into processes below the photosphere and offer clues to identifying their emission mechanisms. We have searched for these neutrinos intensively with IceCube’s existing infill array, DeepCore. Although no significant detections have been made, strong constraints on astrophysical environments in these transients, such as the baryon loading factor in gamma-ray bursts, have been obtained. A denser infill array, called the IceCube Upgrade, will enhance sub-TeV neutrino searches with its unprecedented sensitivity to GeV neutrinos. The Upgrade, set to be deployed in the 2025-2026 South Pole season, will consist of seven new strings, adding approximately 700 novel optical modules with multiple photomultiplier tubes in the DeepCore volume. The denser arrangement of high-efficiency modules will significantly improve IceCube’s sensitivity between 1 GeV and 1 TeV. We present an initial assessment of the astrophysical capabilities of the IceCube Upgrade, using preliminary simulated data and an event selection similar to that used for DeepCore. We explore the detectability of GeV neutrino transients compared to DeepCore and discuss potential sensitivity enhancements through advanced detector simulations and optimized analysis techniques, including refined triggering conditions and event selection criteria.

Speaker: Yukiho Kobayashi (ICEHAP, Chiba University)

16:20 The Giant Radio Array for Neutrino Detection - experimental status and plans

GRAND (the Giant Radio Array for Neutrino Detection) is a proposed next-generation observatory targeting primarily the detection of ultra-high-energy(UHE) neutrinos, with energies exceeding 100 PeV. GRAND is envisioned as a collection of large-scale ground arrays of self-triggered radio antennas that target the radio emission from extensive air showers initiated by UHE particles. Three prototype arrays are presently in operation: GRANDProto300 in China, with 60 units running since the end of 2024, GRAND@Auger in Argentina, with 10 units deployed on the site of the Pierre Auger Observatory, and GRAND@Nançay in France, a 4-unit setup installed at the Nançay Radio Observatory and used for test purposes. The main objective of the GRAND prototype phase is to validate the detection principle and technology of GRAND, in preparation for its next phase, GRAND10k. GRAND10k will consist of two arrays of 10'000 antennas each, in the Northern and Southern hemispheres, to be deployed from 2030 on. We will give an overview of the GRAND concept, its science goals, the status of the prototypes, their first measurements, and the technical and scientific perspectives that these measurements open for the field.

Speaker: Olivier MARTINEAU

16:35 The Radio Neutrino Observatory Greenland (RNO-G)

The Radio Neutrino Observatory Greenland (RNO-G) is being constructed at Summit Station in Greenland. It seeks to detect the radio emission of neutrinos interacting in the 3~km thick ice. Radio detection of neutrinos is sensitive to neutrinos above 10 PeV and therefore complements existing optical detectors. RNO-G currently consists of 8 out of planned 35 stations, each combining the signals of 24 antennas distributed in shallow trenches and three holes of 100~m depths.
This contribution will provide an overview of ongoing activities at RNO-G, with a focus on recent scientific results and plans for future seasons.

Speaker: Anna Nelles (DESY Zeuthen)

15:20 → 16:50 SH: Solar modulation

15:20 Multi-spacecraft observations of the 27-day periodicity in galactic protons from 2018 to 2019 by the HEPD-01 detector on board the CSES-01 satellite and other experiments

Galactic cosmic ray (GCR) intensities exhibit recurrent variations caused by their passage through heliospheric structures co-rotating with the Sun, with the ∼27-day periodicity being the most prominent one. To study this periodicity, data collected by the High-Energy Particle Detector (HEPD-01) on board the China Seismo-Electromagnetic Satellite (CSES-01) in Low-Earth Orbit have been used to derive daily proton fluxes from August 2018 to August 2019, in the energy range between ∼55 and ∼200 MeV. Daily fluxes from HEPD-01 have been analyzed along with proton fluxes measured during the same period by ERNE and EPHIN, on board the SOHO spacecraft, and by AMS-02, on board the International Space Station. Using a classical time-frequency analysis, the ∼27-day periodicity shows a maximum occurring earlier for HEPD-01 than for high-energy data from AMS-02. Additionally, the rigidity dependence of the amplitude of the aforementioned GCR variations cannot be described by the same power law at both low and high energies. The spectrum flattens below ∼0.8 GV with a local minimum at about 0.4 GV, showing a power-law behavior at > 1 GV. HEPD-01 observations fill the energy gap between low-energy (EPHIN, ERNE, etc.) and higher-energy (e.g., PAMELA and AMS-02) space-borne experiments, providing important information for understanding GCR periodicities.

Speaker: Francesco Palma

15:35 Hourly cadence cosmic ray modulation parameter ϕ at first glance: Challenges and possibilities

The flux of galactic cosmic rays (GCR) traversing into and inside the heliosphere are modulated by the magnetic activity of the Sun through the heliospheric magnetic field, as the particles are deflected and slowed down by magnetic discontinuities. This modulation of GCR in the heliosphere can be parametrized by the modulation (potential) parameter ϕ, which is estimated using the force field approximation. Despite the complexity of its full physical interpretation, the parameter is convenient and powerful for studying modulation and, e.g., recreating observed GCR variations when carefully applied with relevant modulation and yield models.

Due to the force-field assumptions, the modulation parameter ϕ is usually only considered on monthly or longer timescales. However, recently results in Väisänen et al. (2023) and Väisänen et al. (2025, In revision) validated that the empirical ϕ parameter based on neutron monitor (NM) count rates does have merit to be considered also on shorter time scales. This top-down approach has many potential uses in improving our space weather, radiation and modulation monitoring capabilities, but still requires further work in validating the methodology and fully understanding the limitations.

Here we propose and discuss the 1-hour cadence modulation parameter ϕ and share preliminary results. Specifically, the shorter-than-day cadence is subject to diurnal variation and anisotropy of the local GCR flux, which need to be separated from the resulting modulation. Subsequently, this will enable us to better understand the GCR anisotropy and diurnal variations, in addition to uses in space weather and background modulation analyses. To better account for the diurnal variations, we have also rigorously computed precise 1-hour cutoff rigidities and particle traces for all the NM stations used in the computation from the year 1964 onwards using the Oulu—Open-source geomagneToSphere prOpagation (OTSO) tool, which is supersedes the previously used MAGNETOCOSMICS tool.

References:
Larsen, N., Mishev, A., & Usoskin, I. (2023). A new open-source geomagnetosphere propagation tool (OTSO) and its applications. Journal of Geophysical Research: Space Physics, 128, e2022JA031061. https://doi.org/10.1029/2022JA031061
Väisänen, P., Usoskin, I., Kähkönen, R., Koldobskiy, S., & Mursula, K. (2023). Revised reconstruction of the heliospheric modulation potential for 1964–2022. Journal of Geophysical Research: Space Physics, 128, e2023JA031352. https://doi.org/10.1029/2023JA031352
Väisänen, P., Bertucci, B., Tomassetti, N., Orcinha, M., Koldobskiy, S., Usoskin, I. 2025. Simulation of Galactic cosmic ray proton fluxes with the daily modulation potential: Validation with AMS02 data for 2011-2019. Journal of Geophysical Research: Space Physics (In Review, preprint: https://doi.org/10.22541/essoar.173532496.66800900/v2).

Speaker: Pauli Kalervo Vaisanen (University of Oulu (FI))

15:50 Solar modulation of cosmic ray electron and positron flux up to 15 GeV measured with DAMPE

The DArk Matter Particle Explorer (DAMPE) is a satellite-borne cosmic particle detector which was launched on Dec. 17th, 2015 into a sun-synchronous orbit with the tilt angle of 97.4 degree. The high energy resolution and large geometric acceptance make the detector suitable for the cosmic ray electron (plus positron) measurement. In this work, the time-dependent electron flux was measured during the solar cycles 24 and 25 (since the beginning of 2016 up to the end of 2024), including the minimum phase of the former one. The result is helpful for studying the transportation process of cosmic ray electrons in the Heliosphere and the underlying interactions.

Speaker: Dr Yang Liu (Purple Mountain Observatory)

16:05 Towards a Physics-based long-term GCR forecasting tool

Galactic cosmic rays (GCRs) are affected by solar modulation while they propagate through the heliosphere. The time variation of GCR spectra is driven by different physical processes, such as advection, diffusion, particle drifts, and adiabatic energy losses, whose relative contribution changes during the solar cycle. Here we present preliminary efforts towards a physics-based long-term GCR forecasting tool. We first constrain the GCR transport parameters with a 3D numerical model, using precise data from the PAMELA and AMS-02, then we relate them with solar and heliospheric quantities, using a mixture density network to obtain proper probability distribution functions for the predicted GCR spectra.

Speaker: Dr Abhinandan Dass (University of Hawai'i at Manoa (US))

16:20 COSMICA: A GPU-Optimized Code for Solar Modulation Studies

We present COSMICA, an opensource high-performance GPU-accelerated numerical code for modeling cosmic ray solar modulation, and its application to study CR diffusion parameters. Developed within the framework of the ICSC-Italian Research Center on High-Performance Computing, Big Data and Quantum Computing (Spoke-3), COSMICA is undergoing continuous software optimization to maximize efficiency on NVIDIA architectures. COSMICA is coupled with SDEGnO, another ICSC project, designed for the efficient parameter tuning, exploring the large parameter space in solar modulation studies. As a first physical use-case study, we exploit COSMICA to investigate Forbush decreases (FDs), which are transient cosmic ray intensity reductions caused by interplanetary disturbances. The analysis leverages the high-precision daily measurements from AMS-02, which provide cosmic ray fluxes across a wide range of rigidities. The ability to simultaneously study not only protons but also helium isotopes offers complementary insights into charge- and mass-dependent transport effects. By analyzing FD events, we assess localized variations in diffusion parameters and their impact on cosmic ray transport. The results confirm the stability of the rigidity dependence of the diffusion tensor, supporting the use of FDs as probes of localized well constrained heliospheric conditions. The computational efficiency of COSMICA paves the way for large-scale simulations, systematic FD catalogue analysis and a more in-depth understanding of the parameter that regulates the solar modulation, together with their dependencies.

Speaker: Stefano Della Torre (Universita & INFN, Milano-Bicocca (IT))

16:35 A modelling study of the solar modulation of galactic protons at lower energies over changing solar activity

The interest in the study of the global features of the modulation of galactic cosmic rays has been increasing since the 23rd solar minimum. This is supported by various detectors such as PAMELA, AMS-02 and HEPD01, providing cosmic ray particles measurements at Earth over two complete solar cycles i.e., the 23rd and 24th. These exceptional observations provide an opportunity for enhanced numerical modeling of the modulation of galactic cosmic rays over a wide range of rigidity at the Earth. In this study a well-established three-dimensional drift model is used to compute proton spectra for these two solar cycles that are compatible with the mentioned observations. The main objective is to adapt the model quantitatively to reproduce global spectral features properly so that proton fluxes can be selectively studied in detail at lower energies, which are strongly affected by the heliosphere in their propagation.

Speaker: Dzivhuluwani Ndiitwani (1.Center for Space Research, North West University, South Africa. 2. School of Physical and Chemical Sciences, North West University, South Africa)

16:50 → 17:05 Break

17:05 → 18:35 CRD: experimental results: heavy and ultra-heavy nuclei

17:05 Properties of Ar and Ca Cosmic Nuclei: Results from the Alpha Magnetic Spectrometer

We report the latest results on the properties of Ar and Ca cosmic rays nuclei fluxes in the rigidity range 2.5 GV to 3 TV based on 0.2 million Ar and 0.3 million Ca nuclei collected by the AMS. We observe that Ar and Ca fluxes are well described by the sums of a primary cosmic ray component (Si flux) and a secondary cosmic ray component (F flux). With our measurements, the abundance ratios at the source Ar/Si and Ca/Si are determined independent of cosmic ray propagation.

Speaker: Qi Yan (Chinese Academy of Sciences (CN))

17:20 Measurement of the iron energy spectrum with DAMPE

DAMPE is a space-based particle detector designed to study high-energy cosmic rays, including electrons, gamma rays, and atomic nuclei. Since its launch in December 2015, it has been operating smoothly for over nine years, recording more than 1.6 billion cosmic-ray particles. DAMPE data have already confirmed spectral breaks for light elements as a hardening break at a few hundred GeV/n and detected a softening at tens of TeV. Iron, the most abundant element with an atomic number greater than 20, plays a crucial role in understanding the universal properties of cosmic rays in our galaxy. With the largest acceptance among all currently operating space-based particle detectors and a long exposure time, DAMPE has a strong potential to extend the iron spectrum up to the PeV range. Results of the cosmic iron flux will be presented, discussing the evidence for spectral features and their statistical significance.

Speaker: Dr Pengxiong Ma (Purple mountain observatory, CAS)

17:35 Measurement of Nickel Flux in Cosmic Rays with the Alpha Magnetic Spectrometer on the International Space Station

We present the properties of the flux of primary cosmic Ni nuclei in the rigidity range from 3 GV to 1.3 TV, based on 30,000 nuclei collected by Alpha Magnetic Spectrometer during 13.5 years of operation from May 2011 to November 2024. The rigidity dependence of the Ni/Fe flux ratio will be equally discussed.

Speaker: Yuhang You (Chinese Academy of Sciences (CN))

17:50 Nickel Measurements in DAMPE Cosmic Ray Data

The Dark Matter Particle Explorer (DAMPE) is a calorimetric, satellite-borne detector that has been operating in orbit for over nine years. One of its key scientific objectives is measuring the flux of cosmic-ray nuclei, crucial for understanding the origins of cosmic rays and their propagation mechanisms.
Nickel, one of the most stable elements alongside iron, is the most abundant heavy element beyond iron in cosmic rays. Measuring its energy spectrum provides valuable insights into the acceleration sources of heavy nuclei and their propagation through the interstellar medium. With DAMPE’s excellent charge resolution (~0.33e for iron) and broad energy range from 10 GeV/n to 1 TeV/n, we can achieve high-precision measurements of the nickel spectrum.
From 2016 to 2024, DAMPE collected over 50,000 nickel candidate events. To minimize iron contamination in heavy nuclei beyond iron, we implemented a machine learning-based track reconstruction method and an updated charge reconstruction algorithm. This work presents these methods and preliminary results on the nickel spectrum in cosmic rays.

Speaker: Haoran Sun (University of Science and Technology of China)

18:05 Status of Ultra-Heavy Galactic Cosmic Ray Analysis for the Two SuperTIGER Antarctic Flights

SuperTIGER (Super Trans-Iron Galactic Element Recorder) is a long-duration balloon-borne instrument designed to directly measure Galactic Cosmic Rays (GCR), resolving individual element peaks from $^{10}$Ne to $^{40}$Zr. SuperTIGER had two successful Antarctic flights: one in 2012 for 55 days and one in 2019 for 32 days. We present the current state of the SuperTIGER analyses, overviewing GCR measurements and source abundances from the 2012 flight, which made exploratory measurements up to $^{56}$Ba. GCR measurements up to $^{40}$Zr support a source model where GCR are accelerated from their source of 80% interstellar medium and 20% massive star material by supernovae in OB associations and refractory elements, which condense onto interstellar dust grains, are preferentially accelerated over volatiles. GCR measurements above $^{40}$Zr show a break in this model, indicating an alternative Galactic cosmic-ray source (GCRS) and/or acceleration model for Z > 40. SuperTIGER GCRS abundances are obtained from the leaky-box interstellar transport model. We also report simulation results on corrections needed for energy loss and charge-changing interactions from the atmospheric overburden and instrument material.

Speaker: Nicole Osborn

18:20 Updates to the results of the Ultra-Heavy Cosmic Ray Analysis with CALET on the International Space Station

The Calorimetric Electron Telescope (CALET), launched to the International Space Station in August 2015 and continuously operating since, measures cosmic-ray (CR) electrons, nuclei, and gamma rays. CALET, with its 30 radiation length deep calorimeter, measures particle energy, allowing for the determination of primary and secondary nuclei spectra and secondary to primary ratios of the more abundant CR nuclei through $_{28}$Ni, while the main charge detector (CHD) can measure Ultra-Heavy (UH) CR nuclei up to and beyond $_{40}$Zr, with our recently submitted results to ApJ showing consistency with ACE-CRIS, SuperTIGER, and HEAO-3 through $_{44}$Ru. By using the special high-duty cycle (~90%) UH trigger in conjunction with a data selection cut that requires events to pass into the Total Absorption Calorimeter (TASC), we have leveraged energy information in our charge assignment routine. Simulations using Geant4 and EPICS are then used to evaluate data cuts in the analysis and corrections. In this ICRC, we will show how these flight simulations align with data, how analysis selection cuts have been made, and how a set of corrections for instrument systematics was produced.

Speaker: Wolfgang Zober

17:05 → 18:35 CRI: extensive air shower

17:05 Testing Hadronic Interaction models with Muon Densities from KASCADE-Grande Data

The study of the muon content in extensive air showers (EAS) is relevant for understanding the origin and nature of cosmic rays. Moreover, muons serve as a sensitive observable to hadronic interactions in air showers, offering insight into high-energy physics processes. However, discrepancies between measured and predicted shower muon content have been reported by some EAS observatories at energies above 100 PeV, hinting to deficiencies of high-energy hadronic interaction models. In this work, we study the muon content of EAS with KASCADE-Grande data for primary energies between 100 PeV and 1 EeV, considering showers with zenith angles $\theta \leq 40 ^{\circ}$. In particular, we estimate the local muon density at a radial distance of 600 m from the shower core and explore its dependence on atmospheric depth by dividing the data into three zenith angle intervals. Adapting the energy scale from the Pierre Auger Observatory we compare the data against predictions of the QGSJET-II-04, EPOS-LHC, and SIBYLL 2.3d hadronic interaction models for pure Fe and H nuclei. We find that local muon densities at this lateral distance attenuate less with atmospheric depth than expected. None of the used hadronic interaction models provide a consistent description across all zenith angles.

Speaker: Ana Laura Colmenero César

17:20 Study on large zenith angle air showers with LHAASO-KM2A

At large zenith angles, the electromagnetic component of ordinary air showers is significantly attenuated by the atmosphere long before reaching ground level. The observation of Horizontal Air Showers (HAS) provides a "well-shielded laboratory" for detecting penetrating particles, such as high-energy muons and cosmic neutrinos, which leave a distinctive signature in this environment.
In this presentation, typical events recorded by LHAASO-KM2A at large zenith angles will be presented, along with the phenomenology of horizontal air showers as measured by LHAASO-KM2A. Additionally, the constraints of the neutrino flux associated with GRB 221009A and other
gamma-ray bursts detected by gamma-ray telescopes in 2022 and located in the observation window will also be addressed.

Speaker: Dr Quan-Bu Gou (Tianfu Cosmic Ray Research Center & Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences)

17:35 Reconstructing Air-Shower Observables using a Universality-Based Model at the Pierre Auger Observatory

Air-Shower Universality is a framework that describes the regularity in the longitudinal, lateral, and energy distributions of electromagnetic shower particles, motivated by solutions to the cascade equations. We employ a universality-based model of shower development that incorporates hadronic particle components to reconstruct observables from extensive air showers produced by ultra-high-energy cosmic rays. The model can estimate key parameters, such as the depth of shower maximum ($X_\text{max}$) and the number of muons ($N_\mu$) at the event level, depending on the input parameters. We present the performance of the reconstruction algorithm using both air-shower simulations, and data from the Pierre Auger Observatory.

Speaker: Dr Darko Veberic (Karlsruhe Institute of Technology (DE))

17:50 A Top-Down Approach to the Muon Puzzle: Validation of the method using the new EPOS LHC-R and QGSJET-III hadronic interaction models

The muon content predicted by hadronic interaction models falls short of describing the data from multiple air shower experiments. This discrepancy, known as the Muon Puzzle, poses significant challenges for mass composition studies and limits our understanding of the origins and acceleration mechanisms of ultra-high-energy cosmic rays. The recent releases of the EPOS LHC-R and QGSJET-III models provide a new opportunity to investigate this divergence using a top-down approach to air shower simulations. This strategy consists of constraining the electromagnetic component of a simulated air shower by matching its longitudinal profile to that of an observed air shower. Consequently, any inconsistency found between the simulated and observed signal in ground particle detectors must originate from a mismatch in the muon content. In the present work, the top-down analysis is tested on a mock dataset that includes air showers simulated with EPOS LHC-R at around 10 EeV and reconstructed using the Pierre Auger Observatory framework. The top-down simulations are performed using QGSJET-III, considering proton, helium, oxygen and iron nuclei as primary particles. The quality of the method is assessed by comparing the true difference in muon content between the two models to that derived from the top-down simulations. Finally, a maximum likelihood estimation accounting for composition is performed to determine the overall hadronic rescaling required to adjust QGSJET-III in order to match the muon content of EPOS LHC-R.

Speaker: Kevin Almeida Cheminant (NIKHEF / Radboud University)

18:05 Evaluation of Hadronic Interaction Models Through Muon Multiplicity Distributions in Extensive Air Showers at the GRAPES-3 Experiment

The GRAPES-3 experiment, located in Ooty, India, consists of a densely packed array of 400 plastic scintillator detectors and a large area ($560 m^2$) muon telescope. The muons produced in extensive air showers (EAS) are key observables for analyzing the primary cosmic ray composition. The GRAPES-3 muon telescope (G3MT) measures the muonic component in the EAS by counting the reconstructed muon tracks based on the proportional counter hit information. A detailed simulation of the EASs is needed to reconstruct the properties of the primary particles. However, the persistent discrepancies among the hadronic interaction models and experimental data at higher energies highlight the need for further analysis and examination of the current models in use. Our comparative analysis of muon multiplicity predictions from 100 TeV to 1 PeV monoenergetic vertical showers, considering proton, helium, nitrogen, aluminum, and iron primaries, shows that the percentage difference among QGSJET II-04, SIBYLL 2.3c, and EPOS-LHC models is within 5% at 100 TeV and decreases at higher energies. Further, in this contribution, we compare the muon multiplicity distributions (MMDs) from experimental data with the predictions of these three hadronic interaction models, reconstructed by assuming the GST composition model. These comparisons are important for testing the hadronic interaction models and improving their predictive accuracy in simulating high-energy cosmic ray interactions.

Speaker: Raveena CR (Amity University Uttar Pradesh, Noida)

18:20 Piritakua: the atmosphere as a high-energy physics laboratory

The atmosphere provides a large set of experimental conditions on which cosmic-ray induced high-energy hadron interactions can take place. These conditions include: sudden changes in the atmospheric pressure, temperature, and in the local electric and magnetic fields. In this talk we introduce the Piritakua (flash of lightning, in the language of the pre-Columbian Purépecha Empire in Mexico) project, a cosmic-ray detector located at the Instituto de Física of UNAM, in Mexico City at 2280 m. a.s.l. The experiment consists of a small array of scintillator detectors, which use the electronics developed by the Cosmic Watch project. The scintillators operate simultaneously with an electric field meter, a magnetometer, a meteorological station, and a hemispheric camera. We propose to use Piritakua to study the modification of the secondary particle production and propagation under sudden variations in the standard atmospheric properties. We present the current status and the first results of the experiment.

Speaker: Hermes León Vargas (Instituto de Física, UNAM)

17:05 → 18:20 CRI: radio detection

17:05 Radio-upgradation of the GRAPES-3 experiment with the beamforming approach.

The GRAPES-3 (Gamma Ray Astronomy at PeV EnergieS phase-3) is a globally recognized experiment that detects cosmic rays with energies in the range from 10$^{13}$ eV to 10$^{16}$ eV. It has an excellent core-reconstruction resolution, approximately 0.5 meters at 1 PeV. We are designing a radio antenna array with 60-70 antennas, envisaged to function along with the array of scintillator detectors, to detect cosmic rays over the PeV energy range. Short radio frequency pulses with lengths of nanoseconds are emitted from cosmic-ray induced air showers which can be detected for cosmic-ray energies of typically 100 PeV and above. Below 100 PeV, the strength of the induced signal starts falling beneath the overwhelming background noise and the detection becomes gradually more challenging. We aim to address these technical challenges with sophisticated beam-forming techniques to lower the radio detection threshold. We are working on a radio upgrade to the GRAPES-3 experiment with the implementation of the beam-forming approach. The existing scintillator-detector array will provide external triggering to the radio detection framework. With the beam-forming approach, we endeavor to lower the radio detection threshold to as low as possible. Using CoREAS simulations, we have demonstrated detection of 10 PeV air-shower events at 4σ detection threshold. We have been using the near-field beam-forming framework to optimize the design of our antenna array. A hierarchical array geometry has elucidated interesting results so far. The advent of the radio-detection facility at the GRAPES-3, may enhance its upper detection threshold significantly.

Speaker: SUBHADIP SAHA (IIT KANPUR)

17:20 Status and Performance of TAROGE-4 for Radio Detection of Extensive Air Showers

The Taiwan Astroparticle Radiowave Observatory for Geosynchrotron Emissions (TAROGE) is an antenna array located atop the high mountains along Taiwan’s eastern coast, oriented toward the ocean. It is designed to detect near-horizon extensive air showers (EAS) induced by ultra-high-energy cosmic rays (UHECRs) and Earth-skimming ultra-high-energy tau neutrinos. The TAROGE array offers several advantages, including high effective live time, low unit cost, and scalability.From 2014 to 2019, four TAROGE stations were deployed, with each successive station incorporating instrumental improvements to enhance detection efficiency. The most recently deployed TAROGE-4 station, operational since 2019, consists of four dual-polarization log-periodic dipole antennas with a bandwidth of 180–350 MHz. This station is equipped with an upgraded trigger system that utilizes Surface Acoustic Wave (SAW) filters and a multi-band coincidence technique, significantly improving the ability to discriminate impulsive geo-synchrotron signals from anthropogenic background noise.In this paper, we provide an overview of the TAROGE project’s detection concept and current status, detail the instrumentation and calibration procedures of TAROGE-4, present the results of the search for EAS candidates, and estimate cosmic ray fluxes based on the detection results.

Speaker: Dr Yaocheng Chen (Leung Center for Cosmology and Particle Astrophysics, National Taiwan University)

17:35 A novel approach for air shower profile reconstruction with dense radio antenna arrays using Information Field Theory

Reconstructing the longitudinal profile of extensive air showers, generated from the interaction of cosmic rays in the Earth's atmosphere, is crucial to understand their mass composition, which in turn provides valuable insight on their possible source of origin. Furthermore, the substructures within the profile allow us to probe the intricate particle interactions that occur within these air showers. Dense radio antenna arrays such as the LOw Frequency ARray (LOFAR) telescope as well as the upcoming Square Kilometre Array (SKA) are ideal instruments to explore the potential of air shower profile reconstruction, as its high antenna density allows cosmic ray observations with unprecedented accuracy. However, current frameworks can only recover parametrisations of the shower and rely heavily on computationally expensive simulations. As such, it is ever more so crucial to develop new analysis approaches that can perform a full air shower profile reconstruction.

In this work, we develop a novel framework to reconstruct the longitudinal profile of air showers using measurements from radio detectors with Information Field Theory (IFT), a state-of-the-art reconstruction framework based on Bayesian inference. Through IFT, we are able to exploit all available information in the signal (amplitude, phase, and pulse shape) at each antenna position simultaneously for reconstructing the profile. Furthermore, we explicitly utilise shower parameters that are motivated through our current understanding of air shower physics to model the profile. We leverage on a novel fast-forward model for the radio emission based on template synthesis which generates traces in the antennas using scaling relations. We apply our framework on simulated datasets based on LOFAR and SKA where we incorporate realistic antenna and noise models. Using our framework, we can not only reconstruct the air shower profile with uncertainties in each bin but also recover the reconstructed trace at each antenna position. We demonstrate that radio measurements from dense antenna layouts such as LOFAR and SKA have the capability to go beyond reconstruction of standard shower parameters which will undoubtedly further our understanding of cosmic ray air showers.

Speaker: Keito Watanabe (Institute for Astroparticle Physics, Karlsruhe Institute of Technology)

17:50 Radio Signatures of Cosmic-Ray Particle Showers in Deep In-Ice Antennas

To detect ultra-high-energy neutrinos, experiments such as ARA and RNO-G target the radio emission induced by these particles as they cascade in the ice, using deep in-ice antennas at the South Pole or in Greenland. In this context, it is essential to first characterize the in-ice radio signatures from cosmic ray induced particle showers, which constitute a primary background for neutrino detection, but also represent the fist in-situ detection of astroparticles with in-ice radio antennas. This characterization will thus validate the detection principle and aids in calibration. To achieve this goal, we used FAERIE, the “Framework for the simulation of Air shower Emission of Radio for in-Ice Experiments”, that combines CoREAS and GEANT4 to simulate the radio emission of cosmic ray showers deep in the ice. Using this innovative tool we analyze in-ice radio signatures of cosmic-ray showers, including polarization, frequency spectrum, and radiation energy, as well as their dependence on shower parameters. These insights will facilitate the first cosmic-ray detections and improve cosmic-ray/neutrino discrimination.

Speaker: Simon Chiche (Inter-University Institute For High Energies)

18:05 Electric Field for Radio Detection of Inclined Air Showers in Three Polarizations

The amplitude, polarization, frequency spectrum, and energy fluence of the electric field at a given measurement position are crucial parameters for extracting primary information from radio signals generated by extensive air showers. Therefore, accurate reconstruction of the electric field from recorded antenna signals is therefore essential for advancing radio detection techniques. Traditional methods primarily target electric field reconstruction using antennas with two horizontal polarizations. In this study, we present an analytical least-squares reconstruction method that works for both two- and three-polarization configurations, enabling accurate electric field reconstruction at each antenna. The method has been validated for both simplified and realistic antenna responses, with particular attention to inclined air showers. It achieves a reconstruction accuracy better than 4% for the amplitude and better than 6% for energy fluence estimation, with minimal bias. The approach is robust across nearly all arrival directions, and the directional dependence has been thoroughly investigated. Notably, incorporating vertically polarized antennas significantly improves reconstruction precision, yielding more accurate electric field estimations for inclined air showers. This method enhances the extraction of cosmic-ray properties from detected radio signals, offering critical advancements for current and future experiments.

Speaker: Kewen Zhang

17:05 → 18:06 GA: AGNs

17:05 Temporal and Spectral Study of Markarian 421's Activity States Using HAWC Data

The High-Altitude Water Cherenkov (HAWC) observatory, located in Volcán Sierra Negra, México, is designed to detect very high-energy (VHE) gamma rays and has provided continuous sky observations in the range of hundreds of GeV to hundreds of TeV since it began operations in 2015. Over nine years (2015–2024), HAWC has revealed the evolution of the light curve of the blazar Markarian 421 (Mrk 421), including both low- and high-activity states. The primary motivation for this work is the VHE flare detected in 2020, the most intense observed to date for this source with HAWC. This event offers a unique opportunity to study the physical processes that occur during extreme activity states in blazars. In this context, we present a temporal analysis of the spectrum of Mrk 421 during its active states, with particular attention to the characteristics and physical implications of this flare.

Speaker: Erick Rangel Anita (Instituto de Astronomía, UNAM)

17:20 SST-1M observation of Markarian 421

Markarian 421 (Mrk 421) is one of the closest and brightest high-frequency peaked blazars, located at a redshift of z = 0.031. It is a strong source of gamma rays, and its broadband emission has been extensively studied over the years through multi-wavelength observations from various telescopes.
Mrk 421 has been a target of observational campaigns conducted by the SST-1M telescopes – two single-mirror small-size Cherenkov telescopes at Ondrejov Observatory, Prague, Czech Republic. These telescopes operate in mono and stereoscopic modes, utilizing the Imaging Atmospheric Cherenkov Technique (IACT) to detect Very High Energy (VHE) gamma rays in the 1–300 TeV energy range.
In this study, we present recent SST-1M observations, data analysis, and the results of physical modeling of Mrk 421's emission mechanisms, as well as a comparative analysis with previous studies.

Speaker: Srija Reddy Muthyala

17:35 Observation of a blazar flare with X-ray polarimetry and VHE gamma rays

In this talk, I will present the first study of an outburst from a high synchrotron peaked blazar (HSP) with X-ray polarimetry and very high-energy (VHE; E >0.1 TeV) gamma ray measurements. While the mechanisms driving flares in blazar jets remain poorly understood, the associated spectral variations imply that particle (re)acceleration must play a central role. For HSPs, the advent of sensitive X-ray polarimetry allows a direct probe of the magnetic field structure impacting the most energetic particles in the jet, leading to unprecedented insights into the most extreme particle acceleration mechanisms. As leptonic scenarios predict that X-rays are emitted by particles that also produce TeV photons, the combination of VHE and X-ray polarimetry data is of prime importance to further constrain the physical origin of flares.

In December 2023 we observed an outburst of the archetypal TeV HSP Mrk 421 from radio to VHE gamma rays with MAGIC, Fermi-LAT, Swift, XMM-Newton, and several optical and radio telescopes. Over a two-week period, a simultaneous characterization of the X-ray polarization was obtained thanks to the Imaging X-ray Polarimetry Explorer (IXPE), in addition to optical and radio polarimetry data. We find substantial variability in both X-rays and VHE gamma rays, with the highest VHE flux occurring during the IXPE observing window, and exceeding twice the flux of the Crab Nebula. The average X-ray polarization degree is significantly higher than that at radio and optical frequencies, suggesting an energy stratification of the emitting region. Notably, the X-ray/VHE flux changes are accompanied by strong variability of the X-ray polarization angle and degree on timescales of days. This behavior points toward a significant impact of plasma turbulence on the origin of X-ray/VHE flux variability. The highest X-ray polarization degree reaches 26%, around which an X-ray counter-clockwise hysteresis loop is measured, implying that the ~keV emission originates from the high-energy cutoff of the particle population. We model the broadband emission with a simplified stratified jet model throughout the flare using daily binned SEDs. Our analysis favors a scenario in which the flare is produced by a turbulent plasma crossing a shock front at which particles get accelerated.

Speaker: Axel Arbet-Engels (Max Planck Institute for Physics)

17:50 On the multi-zone Synchrotron polarization of blazars

I will show that current mm-to-X-ray polarization trends observed during recent IXPE campaigns for high-synchrotron peaked blazars and the ROBOPOL trend for Fermi blazars, which relate the fractional polarization to the peak frequency of the synchrotron emission, can be successfully reproduced by a multi-zone scenario without the need for an energy-stratified scenario. I will also discuss some implications for the statistical properties of the polarization angle and the underlying acceleration processes.

Speaker: Dr Andrea Tramacere (Université de Genève)

17:05 → 18:20 GA: ground experiments

17:05 Development of PANOSETI Telescopes for Ultra-High-Energy Gamma-Ray Astronomy

Ultra-High-Energy (UHE, E >100 TeV) gamma rays are one of the few channels to search for and study galactic PeVatrons. Among the most promising PeVatron candidates are the many UHE gamma-ray sources that have recently been identified on the Galactic Plane. Ground-based particle detectors see these sources as extended rather than point-like, and current generation Imaging Atmospheric Cherenkov Telescopes (IACTs) struggle to study them with effective areas and background rejection that are suboptimal at UHE. A cost-efficient way of constructing an array of IACTs explicitly designed for UHE sensitivity is to sparsely separate many small telescopes. We have simulated, prototyped, and twice deployed a pathfinder array that is instrumented with telescopes designed by the Panoramic Search for Extraterrestrial Intelligence (PANOSETI) team. These 0.5-meter Fresnel lens telescopes are purpose-built for imaging optical transients on nanosecond timescales and are equipped with a 10°x10° silicon photomultiplier camera. Three PANOSETI telescopes were deployed twice in the same temporary configuration at Lick Observatory in March and October 2024. Here we give a brief description of the instrument and present a comparison of simulations with the data collected, including an analysis of the Crab Nebula. We also report on the ongoing deployment of the five-telescope Dark100 array that is planned to operate for five years at Palomar Observatory.

Speaker: Nikolas Korzoun (University of Delaware)

17:20 Characteristics measurement of plastic scintillators and performance evaluation of cosmic ray measurement for the ALPAQUITA experiment

The ALPACA experiment is a new project in Bolivia designed to observe cosmic rays and gamma rays in the TeV–PeV energy range. It consists of a large air-shower array (83,000 m²) and a water-Cherenkov-type muon detector (3,600 m²) and aims to survey PeVatron candidates in the southern sky, including the Galactic Center. The surface detectors of the prototype array, ALPAQUITA, has been fully operational at the Chacaltaya plateau (4,740 m a.s.l.) in Bolivia since April 2023. It comprises 97 scintillation detectors, each with an area of 1 m², deployed with 15 m spacing.
In this research, we conducted a characterization of the scintillators used in the ALPACA and ALPAQUITA surface arrays. As a result, we obtained expressions for charge amount, signal delay, and time transit spread (t.t.s.) as functions of the distance from the center of the scintillator box. Additionally, we performed a Monte Carlo simulation using CORSIKA to generate 10⁹ cosmic ray events with energies ranging from 280 MeV to 10 PeV and reproduced the detector response using Geant4. The functions obtained from the scintillator characterization were incorporated into the detector response modeled in Geant4. As a result, the counting rates were found to be 52,000 per second for any1, 1,400 per second for any2, 530 per second for any3, and 290 per second for any4.
Furthermore, we compared the Monte Carlo data with the experimental data from ALPAQUITA for the Σρ distribution, which serves as an energy indicator of primary particles detected by the apparatus, the zenith angle distribution of the arrival direction, and the even-odd opening angle distribution, which serves as an indicator of angular resolution. In all cases, good agreement was observed.

Speaker: Mizuno Atsushi (ICRR)

17:35 Evaluating the scientific potential and performance of Gammalearn on LST-1 observations

The upcoming Cherenkov Telescope Array Observatory (CTAO) represents the next generation of Imaging Atmospheric Cherenkov Telescopes (IACTs), offering a significantly enhanced sensitivity, up to five to ten times greater than existing instruments. Its first prototype, the Large-Sized Telescope (LST-1), is currently operational at the Roque de los Muchachos Observatory in La Palma, Spain. Deep learning techniques have shown promising results in reconstructing key physical properties of incident particles, such as energy, arrival direction, and particle classification, when applied to simulated data. While traditional techniques rely on simple parameterization of the shower image shape, deep learning can leverage the full temporal and charge information of the images, extracting additional information that is particularly valuable at the lowest energies (~20 GeV) accessible by LST-1. These insights are crucial for studying distant extragalactic sources, such as Active Galactic Nuclei, which can serve as probes for fundamental physics and cosmology. In this context, GammaLearn, a deep learning framework for IACTs data analysis, has demonstrated strong potential in this energy range (Vuillaume et al., 2021, ICRC).
Here, we apply GammaLearn to observational data from LST-1 to assess its performance on real data.

Speaker: Guillaume GROLLERON

17:50 Calibration and Performance Validation of the SST-1M Telescopes Using Crab Nebula Observations

SST-1M is a prototype single-mirror Small-Sized Cherenkov Telescope
designed for very-high-energy (VHE) gamma-ray astronomy. With a 4
meter primary mirror and a 5.6 meter focal length, it provides a wide 9-degree field of view, optimized for detecting VHE gamma-rays from 1 TeV
to several hundred TeV. Its focal plane is equipped with DigiCam, a fully
digital trigger and readout camera made of 1296 silicon photomultiplier
(SiPM) pixels. The use of SiPM sensors enables observation under high
night sky background (NSB) conditions, significantly enhancing the in-
strument’s duty cycle and allowing observations under moonlight.

Currently, two SST-1M telescopes are deployed at the Ondřejov Ob-
servatory in the Czech Republic, operating in stereo, at 500 m altitude, to
observe astrophysical sources. This contribution presents the SiPM cal-
ibration procedure and performance validation of the instrument, based
on updated results from Crab Nebula observations. The SiPM response
and overall instrument performance under varying NSB conditions will be
discussed.

Speaker: Thomas Tavernier

18:05 Line-of-Sight Trigger(LOST) project of LHAASO-WCDA

With a large field-of-view and almost full duty cycle, LHAASO-WCDA is appropriate to monitor the VHE emission from extra-galactic transient sources like GRBs and AGNs, or galactic variable sources like binaries, pulsars and nova. However, these sources either suffer from severe EBL absorption at high energies or have an energy spectral cutoff at sub-TeV range, making them faint or even invisible with the current sensitivity of WCDA. To fulfill WCDA’s potential, we came up with the Line-of-Sight-Trigger(LOST) to lower WCDA’s energy threshold to < 100GeV range. The main idea of LOST is to have WCDA imitate a telescope, point to the source direction to enable a looser trigger and reconstruct lower energy events. We present the performance estimation of LOST and preliminary results on experiment.

Speaker: Ruiyi Tang (Tsung-Dao Lee Institute, Shanghai Jiao Tong University)

17:05 → 18:21 NU: experimental & next generation

17:05 Current Status of TAMBO: Realizing PeV Neutrino Astronomy with a Cost-Effective Observatory

The detection of high-energy astrophysical neutrinos by IceCube has opened a new window on our Universe. While IceCube has measured the flux of these neutrinos at energies up to several PeV, much remains to be discovered regarding their origin and nature. Currently, the discovery of point sources of neutrinos is hindered by atmospheric neutrino backgrounds; likewise, astrophysical neutrino flavor ratio measurements are limited by the difficulty of discriminating between electron and tau neutrinos.

TAMBO is a next-generation neutrino telescope specifically designed to detect tau neutrinos in the 100 TeV to 1 EeV energy range at a fraction of the cost of traditional neutrino telescopes. The tau neutrino specificity enables the low-background identification of astrophysical neutrino sources, as well as tests of the flavor ratio of astrophysical neutrinos. Additionally, the high-energy reach of TAMBO will allow us to probe models of cosmogenic neutrino production. TAMBO will comprise an array of water Cherenkov and plastic scintillator detectors deployed on the face of a deep valley, with its unique geometry facilitating the high-purity measurement of astrophysical tau neutrinos. In this talk, I will present the particle physics and astrophysics that TAMBO will study in the context of next-generation neutrino observatories. I will also provide an update on the status of detector construction.

Speaker: Will Thompson (Harvard University)

17:20 The Hybrid Elevated Radio Observatory for Neutrinos (HERON) Project

Measuring ultra-high energy neutrinos, with energies above 10^16 eV, is the next frontier of the emerging multi-messenger era. Their detection requires building a large-scale detector with 10 times the instantaneous sensitivity of current instruments, sub-degree angular resolution, and wide daily field of view. The Hybrid Elevated Radio Observatory for Neutrinos (HERON) is designed to be that discovery instrument. HERON leverages the best features of two leading-edge radio techniques demonstrated by the BEACON and GRAND prototypes. Its preliminary design consists of 24 compact, elevated phased stations with 24 antennas each, embedded in a sparse array of 360 standalone antennas. This setup tunes the energy threshold to below 100 PeV, where the neutrino flux should be high. The exquisite sensitivity of the phased stations combines with the powerful reconstruction capacities of the standalone antennas to produce an optimal detector. HERON is planned to be installed at an elevation of 1,000 m across a 72 km-long mountain range overlooking a valley in Argentina’s San Juan province. It would be connected to the worldwide network of multimessenger observatories and search for neutrino bursts from candidate sources of cosmic rays, like gamma-ray bursts and other powerful transients. With HERON’s deep sensitivity, this strategy targets discoveries that cast new light into the inner workings of the most violent astrophysical sources at uncharted energies. We present the preliminary design, performances, and observation strategy of HERON.

Speaker: Kumiko KOTERA

17:35 Searching for Ultrahigh Energy Neutrinos with PUEO

PUEO, the Payload for Ultrahigh Energy Observations, is a long duration balloon-borne experiment with the primary science goal of detecting the impulsive Askaryan emission from ultrahigh energy (>1 EeV) neutrinos interacting in the ice sheet of Antarctica. The ultrahigh energy neutrino flux is yet to be detected, and so a successful measurement by PUEO will give us information about the where and how these neutrinos are produced; this may be through a process called the GZK effect when ultrahigh energy cosmic rays interact with the cosmic microwave background, or it may be directly within the environment of cosmic ray accelerators.

In order to detect radio Askaryan emission, PUEO consists of a broadband interferometric radio detector of 96 antennas which point down at the ice. Additionally, it has a drop-down low-frequency subsystem which will deploy after launch. This improves PUEO's ability to detect tau neutrinos and charged cosmic rays, which can both produce geomagnetic air shower emission. This contribution will outline PUEO's science case, present its expected sensitivity, and share status updates from our preparation to launch PUEO from McMurdo Station, Antarctica in December 2025.

Speaker: Quincy Abarr (University of Delaware)

17:50 First instrumented line of the Pacific Ocean Neutrino Experiment: status, development and outlook.

The Pacific Ocean Neutrino Experiment (P-ONE) is a planned water-based Cherenkov neutrino telescope that will be located off the West Coast of Canada. P-ONE will observe high-energy astrophysical neutrinos, aiming to identify the sources where they are produced, and will allow long-term in-situ studies of bioluminescence in the Cascadia Basin. The detector will be composed of instrumented mooring lines, which, along with the existing deep-sea infrastructure of the NEPTUNE observatory, make the design easily scalable. The first phase of the experiment, called P-ONE-1, is the first complete detector line and is instrumented with 20 modules spanning one kilometer. P-ONE-1 will serve as a test for all the newly developed systems and infrastructure and will pave the way for the future phases. This contribution will give an overview of the current status of the construction of the first line, the expected performance and the recent design innovations.

Speaker: Cristina Lagunas Gualda

18:06 Contribution of young massive stellar clusters to the Galactic diffuse neutrino and gamma-ray emissions

Young massive stellar clusters (YMSCs) have emerged as energetic non-thermal sources, after the recent observation of extended gamma-ray emission by a dozen YMSCs. The large size of their gamma-ray halos, of the order of the excavated bubble from the collective wind, makes the detection of individual YMSCs rather challenging because of the low surface brightness. As a result, the emission from most of the Galactic YMSCs could be unresolved, thus contributing to the diffuse gamma-ray and neutrino radiation observed along the Galactic Plane. In this study, we estimate that possible contribution of the population of YMSCs to the Galactic diffuse radiative emissions, by simulating synthetic samples of these sources resembling the observed properties of local clusters. We compute the resulting secondary emission from hadronic interactions occurring in each cluster by particles accelerated at the cluster’s collective wind termination shock and at the supernovae exploded in the core, and compare them with diffuse gamma-ray and neutrino observations by different experiments, including Fermi-LAT, LHAASO, and IceCube.

Speaker: Stefano Menchiari (IAA - CSIC)

17:05 → 18:21 SH: stars and planets

17:05 Cosmogenic 10Be as a tracer of cosmic-ray variability: Atmospheric transport model and its parameterisation

A new full model of the atmospheric transport of cosmogenic 10Be is presented which allows linking its production by cosmic rays with the measured concentrations in ice cores. The model is based on the focused SOCOL‐AERv2‐BE chemistry‐climate model coupled with the CRAC:10Be isotope production model. It includes all the relevant atmospheric processes and allows computing the isotope concentration in air at any given location and time for the given cosmic-ray flux. The model is validated with the measurements of 10Be in several polar ice cores located in Antarctica and Greenland for 1980–2007. The results imply that the model correctly reproduces the large‐scale atmospheric dynamics but does not accurately resolve synoptic‐scale variability. The dominant source of 10Be is found to be located in the middle stratosphere (25–40 km), in the tropical (<30° latitudes) and polar (>60°) regions, as produced by galactic cosmic rays and solar energetic particles, respectively. It is shown that the majority of 10Be produced in the atmosphere reaches the Earth's surface within one–two years. We also present a practical parameterization of the full‐model results that are easy to compute and offer an accuracy of 20% in polar regions. This practical approach can be applied to studies of solar and geomagnetic variability using cosmogenic isotopes.

Speaker: Ilya Usoskin (University of Oulu (FI))

17:20 Measurement of the neutron spectrum and dose in the SAA region during strong solar activity episodes by the SAMADHA experiment

The main aim of the SAMADHA project is to monitor the cosmic ray neutron
spectrum and dose at very high altitudes in the South Atlantic Anomaly
region during the maximum activity of the 25$^{th}$ solar cycle.

The experimental setup for this measurement consists of an Extended Bonner
Sphere System and a commercial Rem counter. A linear energy transfer
spectrometer to measure the electromagnetic part of the extensive
air showers, and a high-precision barometer to correct
the effect of the atmospheric pressure variations, complete the system.
The experiment is operated at the Chacaltaya Cosmic Ray Laboratory in
Bolivia,
5240 m above sea level, and can be remotely controlled via an Internet
connection.

The instruments have been collecting data almost continuously since March
2023, together with a 12NM-64 neutron monitor managed by the local
research group. This high energy neutron detector monitors variations in
the flux of cosmic rays, which can be used to identify the periods of most
intense solar activity.

We looked at some important Forbush Decreases that occurred in 2024 after
strong CMEs from the Sun searching for cross correlations in our data. In
this paper, we compare the neutron spectrum and dose measured during these
episodes with the spectrum measured during quieter periods.

Speaker: Dr Carlo Francesco Vigorito (University & INFN, Torino, Italy)

17:35 Galactic cosmic ray fluxes during the lifetime of a red dwarf star

Exoplanets orbiting red dwarf stars in the habitable zone are easier to detect than those orbiting Sun-like stars. In recent years, there has been increased interest in modelling the Galactic cosmic ray fluxes reaching exoplanets orbiting stars other than the Sun. This is because Galactic cosmic rays can affect exoplanet habitability by for instance, driving the formation of prebiotic molecules, the building blocks of life, in the atmospheres of planets.

The stellar wind properties are important in determining the level of suppression that affects Galactic cosmic ray fluxes. Detecting the stellar wind from low-mass stars directly is extremely difficult due to their low density. As a result, we use a stellar wind model motivated by observations. First, we use a rotation evolution model to determine the rotation rate and X-ray luminosity of a red dwarf star during its life, from 600Myr - 6Gyr. Using these two quantities we calculate the large-scale stellar magnetic field strength, coronal temperature and mass loss rate of the star which are used as inputs for the stellar wind model.

I will present our results on the Galactic cosmic ray fluxes reaching the habitable zone of a red dwarf star during its life. For this study, we used a 1D diffusion-advection cosmic ray transport model. I will show our results of the Galactic cosmic ray fluxes in the habitable zone vary significantly on Gyr timescales and are different to the fluxes expected around a Sun-like star. I will also show how our results depend on the rotation evolution of the red dwarf. Finally, I will discuss briefly how observations with JWST, and upcoming missions such as Ariel, may probe the high-energy environment of gas giants and provide constraints for our models.

Speaker: Donna Rodgers-Lee (Dublin Institute for Advanced Studies)

17:50 Solar Neutrino Data v.s. Standard Core Physics: Reconciling CNO Flux Anomalies via Opacity and Key Nuclear Cross-Section Revisions

This study confronts the Standard Solar Model (SSM) with observed neutrino fluxes (pp, pep, Be7, B8, CNO) by constructing parameterized solar core models (SCMs) with variable helium/metallicity profiles and equilibrium nuclear burning assumptions for pp chains. We find key tension emerges that no SCM simultaneously satisfies all observed neutrino fluxes, notably due to core temperature-driven discrepancies in pep, B8, and CNO neutrinos. Reducing radiative opacity by ~13% or enhancing 14N(p,γ)15O rates by ~26% aligns CNO fluxes with observations (1-sigma). Crucially, SCMs isolate opacity and nuclear rate dependencies, bypassing uncertainties from convection/diffusion physics. Future work will integrate helioseismic constraints to resolve core radius sensitivity challenges in multi-probe analyses.

Speaker: Prof. Yufeng Li (Institute of High Energy Physics, Beijing)

18:05 The Influence of SEPs and Cosmic Rays on the Early Earth Atmosphere

Solar energetic particles (SEPs) and cosmic rays are high energy particles that impact Earth's atmosphere. One key way that these particles interact with the material in the atmosphere is by ionising atoms and molecules, resulting in changes in the atmosphere’s chemistry. They may even have contributed to the formation of prebiotic molecules, the “building blocks” for life, on Earth's surface at the time when life is thought to have begun on Earth. Therefore, understanding the number of high-energy particles reaching the Earth's surface at this time is of key importance.

The intensity and energy of the energetic particles reaching the top of Earth’s atmosphere depend heavily on the young Sun’s magnetic field strength and solar wind velocity. I focus on energetic particles in a post-impact early Earth atmosphere which is different from the present-day Earth’s atmosphere.

In this post-impact atmosphere scenario the number of cosmic rays at the top of Earth’s atmosphere is lower than the present day as the solar wind’s faster velocity and strong magnetic field strength suppress the cosmic rays diffusing into and through the solar system. SEP numbers at the top of Earth’s atmosphere are increased in this scenario due to the higher activity expected from the younger Sun.
I will discuss how I simulate the transport of both SEPs and cosmic rays through this post-impact early Earth atmosphere and calculate the ionisation rate as a function of height due to these energetic particles. I will discuss how these ionisation rates can be used in chemical models to calculate the abundances of prebiotic molecules in a hydrogen-dominated atmosphere.

I will discuss how the position of the solar system in the Galaxy and in relation to star-forming regions influences the cosmic ray spectrum in the post-impact early Earth atmosphere.

Speaker: Donna Rodgers-Lee (Dublin Institute for Advanced Studies)

Thursday 17 July

08:30 → 09:00 Registration

09:00 → 10:30 Plenary session

09:00 Spectrum and anisotropies of Galactic cosmic rays: a laboratory for magnetic fields

Much has been learned about Galactic cosmic rays in the past decade: On the observational side, the spectra of cosmic ray nuclei have been directly measured with high precision, resolving chemical composition up to TV rigidities. At even higher rigidities, direct detection is making contact with indirect observations from air shower arrays. A number of breaks have been found in the nuclear spectrum, which was previously thought to be a pure power law up to the knee. Data from air shower arrays also show interesting features in the arrival directions of cosmic-ray nuclei. On the theoretical side, more sophisticated models are able to explain the various spectral breaks either with transitions between different classes of sources or with changes in the transport regime. Yet, it has become clear that our ignorance of the structure of the Galactic magnetic fields, both on large and small scales, is limiting precision predictions. Turning this problem into an opportunity though, we can use Galactic cosmic rays as a laboratory for the study of Galactic magnetic fields. In this review talk, I will summarise what is known about the spectrum and anisotropies of Galactic cosmic rays, what is not known yet and what can be learnt in the future.

Speaker: Philipp Mertsch (RWTH Aachen University)

09:45 Understanding magnetism across the universe in the era of next generation radio telescopes

The pursuit of understanding the structure and origin of Galactic and extragalactic magnetic fields is a central science driver for current and future radio telescope surveys. Magnetic fields are pervasive and thought to be a critical driver in many astrophysical processes across all physical scales from solar flares to exoplanet habitability, stellar evolution, galactic turbulence, cosmic ray acceleration and propagation, and the evolution of the Universe. Radio polarisation observations offer a unique probe of both the line-of-sight and plane-of-sky components of the magnetic field, yet the interpretation is extremely challenging due to Faraday rotation effects, and that we are integrating a vector quantity along vast lines of sight. New projects on next generation instruments are providing key information including wide bandwidths and sensitive, high resolution data that are necessary to disentangle this complex information. Some of these exciting projects include, the Polarisation Sky Survey of the Universe’s Magnetism (POSSUM), which uses Australian Square Kilometre Array Pathfinder (ASKAP) telescope, the Very Large Array Sky Survey (VLASS), the LOw-Frequency ARray (LOFAR) Two-metre Sky Survey (LoTSS), The Global Magneto-Ionic Medium Survey (GMIMS), and the upcoming International SKA Observatory. These data are giving us an unprecedented view of the polarised radio sky, changing the way we think about the formation and evolution of planets, stars, galaxies, and the universe itself. These massive datasets are also posing new challenges to the traditional ways that we visualise and analyse such data, forcing us to innovate new approaches. I will discuss progress thus far, as well as the remaining challenges, and highlight the new ways these data will revolutionise our understanding of magnetism across the universe.

Speaker: Jennifer West (National Research Council of Canada)

10:30 → 11:00 Coffee

11:00 → 12:00 Plenary session

11:00 eROSITA highlights

In this presentation, I discuss the recent highlights from eROSITA observations.
In particular, I will discuss the findings about our Milky Way and its bubbles as well as measurements of the circumgalactic medium.

Speaker: Dr johan comparat (Max Planck fuer extra-terrestrische Physik (MPE))

11:30 Unveiling the gravitational-wave background with pulsar timing arrays: current results and future observations

In 2023, multiple pulsar-timing-array collaborations reported evidence for a low-frequency background of gravitational waves. The amplitude and spectral shape of the background are consistent with emission from the population of supermassive black-hole binaries at the centers of galaxies, but more exotic sources are not excluded. I will explore the collection and analysis of pulsar-timing-array data, the key findings reported so far, the implications for our understanding of galaxy evolution and black-hole populations, and the future of this emerging field as more data are collected and more sensitive radiotelescopes enter operation.

Speaker: Prof. Michele Vallisneri (ETH Zurich)

12:00 → 13:20 Lunch

13:20 → 14:50 CRD: induced ionisation & miscellaneous

13:20 Cosmic-ray induced ionisation and spatio-temporal correlations between supernova remnants and molecular clouds

MeV cosmic rays can penetrate dense molecular clouds and oftentimes dominate the ionisation, thus contributing to the physical and chemical dynamics of star forming regions. The effect of cosmic rays can be quantified by their ionisation rate. Interestingly, the ionisation rate predicted from the locally measured cosmic-ray fluxes is one to two orders of magnitude lower than the observed ionisation rates. This disagreement is known as the ionisation puzzle. Previously, it was shown that the point-like nature of cosmic-ray sources implies a stochastic scatter in the stochastic ionisation rates. Drawing distances between clouds and supernova remnants randomly, the discrepany between model and observations could be reduced. Here, we extend this model by considering spatial and temporal correlation between source and cloud positions. These are to be expected to a certain degree as supernova remnants are likely formed in the same cloud complexes. We will present the predictions for different assumptions on the correlations and compare to ionisation data.

Speaker: Philipp Mertsch (RWTH Aachen University)

13:35 Reevaluation of the Cosmic-Ray Ionization Rate in Diffuse Clouds

During the last decade, Voyager spacecrafts have measured the very local interstellar spectra of cosmic-ray (CR) particles down to energies of about 3 MeV. These measurements represent unique information on unmodulated CR spectra below a few GeV. Otherwise, properties of such low-energy CRs can only be probed indirectly. A universal parameter characterizing their impact on a medium is the ionization rate (CRIR), which is usually estimated from observed abundances of certain ions that can only be produced by CRs. Because of its particularly simple chemistry, H3+ is often considered as the most reliable tracer of CRIR in diffuse molecular gas. Available H3+ observations in the local Galactic environment (within 1 kpc) are also the most numerous, which makes it possible to evaluate how CRIR varies in space. All previous estimates of CRIR rely on model-dependent assessments of the gas density along the probed sight lines [1,2], and the resulting values of CRIR typically exceed the values derived for the Voyager spectra by an order of magnitude.

We revisited data from H3+ measurements, by utilizing the recently developed 3D dust extinction maps that enable direct reconstruction of the 3D gas density distribution [3]. High-resolution maps developed for the local Galactic environment allow us to precisely identify the location of molecular clouds probed in each H3+ measurement, and also derive the gas density in these clouds. By performing numerical simulations of the 3D physical structure of the clouds and comparing the results with measured H3+ and H2 column densities, we were able to evaluate CRIR in each cloud without involving any model-dependent assumption about the environment [4].

Our results indicate that (i) values of CRIR probed in individual diffuse molecular clouds in the local Galactic environment may vary by an order of magnitude from cloud to cloud, and (ii) the average CRIR value is a factor of ~10 smaller than that derived previously. We will present details of the preformed analysis, discuss correspondence of our results to the Voyager measurements, and highlight the profound implications for understanding the origins of low-energy CRs.

[1] Indriolo, N. McCall, B. J. 2012, ApJ, 745, 91
[2] Albertsson, T., Indriolo, N., Kreckel, H., et al. 2014, ApJ, 787, 44
[3] Edenhofer, G., Zucker, C., Frank, P., et al. 2024, A&A, 685, A82
[4] Obolentseva, M., Ivlev, A. V., Silsbee, K., et al. 2024, ApJ, 973, 142

Speaker: Marta Obolentseva

13:50 Estimating cosmic-ray induced ionization rates in molecular clumps close stellar clusters

Low-energy cosmic rays (LECRs) are a vital ingredient of the interstellar medium (ISM). Unlike ionizing radiation, they can penetrate deeply in dense environments and are considered as the main ionizing agent for the core of molecular clumps, ultimately determining their stability against gravitational collapse. Young massive star clusters are known to shape the surrounding ISM, excavating large cavities inflated by the powerful winds blown by the OB stars hosted in their core. The presence of these wind-blown bubbles can affect the propagation of LECRs, preventing their penetration into these cavities. Because of this, molecular clumps embedded in wind-blown bubbles are not reached by sub-GeV particles. The lack of LECRs can favor the gravitational collapse of such clumps, effectively representing a positive (never explored) feedback channel for star formation. In this work, we present an estimate of the LECR-induced ionization rate for molecular clumps embedded in wind-blown bubbles. We also account for the presence of cosmic rays produced by the star cluster, and we discuss how their inclusion can increase the ionization rate, leading to a possible negative feedback for star formation.

Speaker: STEFANO MENCHIARI (IAA-CSIC)

14:05 Can cosmic rays explain the high ionisation rates in the Galactic centre?

The Central Molecular Zone (CMZ), located in the centre of the Milky Way, is a roughly cylindrical structure of molecular gas extending up to $\sim 200$ parsecs around the supermassive black hole Sagittarius A$^*$. The average H$_2$ ionisation rate in the CMZ is estimated to be $2 \times 10^{-14} \, \mathrm{s}^{-1}$, which is 2–3 orders of magnitude higher than anywhere else in the Galaxy. Due to the high gas density in this region, electromagnetic radiation is rapidly absorbed, leaving low-energy cosmic rays (CRs) as the only effective ionising agents. Hence, a high CR density has been invoked to explain such high ionisation rates.

However, a corresponding excess in $\gamma$-rays, which would result from interactions of high-energy CRs, has not been observed. This suggests that the supposed excess exists only in the low-energy CR spectrum. To constrain this unknown low-energy component, we first derive the high-energy CR injection spectra using $\gamma$-ray and radio data, to which we add various low-energy components. We then propagate these injection spectra by numerically solving the CR transport equation using a Crank–Nicolson scheme. Testing multiple CR injection scenarios, we find that the energy required to sustain the observed ionisation rates is excessively high in every case.

We conclude that CRs cannot be the exclusive ionising agents in the CMZ. However, significant uncertainties remain in ionisation rate measurements and $\gamma$-ray observations due to uncertainties in the total mass and gas distribution in the CMZ. New results on H$_3^+$-tracing of ionisation rates indicate that these rates must be re-evaluated in the CMZ, which may allow for an explanation involving CRs.

Speaker: Sruthiranjani Ravikularaman (Ruhr-Universität Bochum)

14:20 Acceleration and Transport of the Unstable Cosmic-ray Isotope 60Fe in Supernova-Enriched Environments

The unstable isotope $^{60}$Fe, with a half-life of 2.6 million years, is produced primarily in supernova explosions. The observed presence of $^{60}$Fe in cosmic rays and its detection in deep-sea crusts and sediments suggest two possible scenarios: either the direct acceleration of $^{60}$Fe from supernova ejecta or its enrichment in the circumstellar material surrounding supernova progenitors, which indicates cosmic ray production in clusters of supernovae. Focusing on the latter scenario, we consider an environment shaped by successive supernova explosions, reminiscent of the Local Bubble around the time of the most recent supernova explosion. We independently tracked the evolution of the $^{60}$Fe mass ratio within the Local Bubble using passive scalars. To investigate the spectra of protons and $^{60}$Fe, we explicitly modelled cosmic-ray acceleration and transport at the remnant of the last supernova by simultaneously solving the hydrodynamical equations for the supernova outflow and the transport equations for cosmic rays, scattering turbulence, and large-scale magnetic field, using the time-dependent acceleration code RATPaC. The main uncertainty in our prediction of the local $^{60}$Fe flux at about $pc=1$ GeV/nuc is the magnetic-field structure in the Local Bubble and the cosmic-ray diffusion beyond the approximately $100$ kyr of evolution covered by our study. We found that if the standard galactic propagation applies, the local $^{60}$Fe flux would be around 3% of that measured. If there is a sustained reduction in the diffusion coefficient at and near the Local Bubble, then the expected $^{60}$Fe flux could be up to 30% of that measured.

Speaker: Xinyue Shi (DESY)

14:35 Investigating the CREDIT history of supernova remnants as cosmic-ray sources

Supernova remnants (SNRs) have long been suspected to be the primary sources of Galactic cosmic rays. Over the past decades, great strides have been made in the modelling of particle acceleration, magnetic field amplification, and escape from SNRs. Yet while many SNRs have been observed in nonthermal emission in radio, X-rays, and gamma rays, there is no evidence for any individual object contributing to the locally observed flux. Here, we propose a particular spectral signature from individual remnants that is due to the energy-dependent escape from SNRs. For young and nearby sources, we predict fluxes enhanced by tens of percent in narrow rigidity intervals; given the percent-level flux uncertainties of contemporary cosmic-ray data, such features should be readily detectable. We model the spatial and temporal distribution of sources and the resulting distribution of fluxes with a Monte Carlo approach. The decision tree that we have trained on simulated data is able to discriminate with very high significance between the null hypothesis of a smooth distribution of sources and the scenario with a stochastic distribution of individual sources. We suggest that this cosmic-ray energy-dependent injection time (CREDIT) scenario be considered in experimental searches to identify individual SNRs as cosmic-ray sources.

Speaker: Anton Stall (Institute for Theoretical Particle Physics and Cosmology (TTK), RWTH Aachen University)

13:20 → 14:50 CRI: extensive air shower model

13:20 Innovative Approaches to Unravel the Shower Components' Energy Spectrum with a Single Hybrid Station

Accurately measuring the energy of shower particles reaching the ground remains a challenge due to the inherent limitations of typical cosmic ray experiments. In this work, we present two experimental strategies to determine the energy spectra of the electromagnetic and muonic components of extensive air showers, leveraging a single hybrid detector station within a regular cosmic ray array. This station consists of a scintillator surface detector (SSD), a water Cherenkov detector (WCD), and Resistive Plate Chambers (RPCs), with a prototype currently being tested at the Pierre Auger Observatory.

The first approach exploits the different responses of each detector to the same particles traversing them, allowing, for the first time, the extraction of the high-energy tail of the electromagnetic spectrum and the low-energy tail of the muonic spectrum. The second strategy utilizes machine learning tools to reconstruct the direction of muons using the WCD+RPC system. By correlating this information with the reconstructed muon production depth, the muon kinematical delay can be analyzed, providing access to its energy spectrum.

Speaker: Ruben Conceição (Laboratory of Instrumentation and Experimental Particle Physics (PT))

13:35 Overview of the CORSIKA 8 astroparticle simulation framework

The simulation of particle cascades is an essential foundation for the analysis chains of many astroparticle physics experiments, irrespective of whether they investigate primarily charged cosmic rays, very high-energy photons or neutrinos, or even dark matter. The most widely used software for simulating such particle showers is CORSIKA, originally developed as COsmic Ray Simulation for KASCADE. For more than 20 years, CORSIKA has been the de-facto standard for air-shower simulations.
CORSIKA 8 is the next stage in the evolution of air-shower simulations. It is designed as a modular and modern C++ framework, that, building on the strong foundation of its predecessor, provides the flexibility that is needed for the next-generation of astroparticle physics experiments.
The development of CORSIKA 8 has reached the state that the code is "physics-complete". In addition to the standard hadronic interaction models for air showers it also includes the “next generation models” EPOS-LHC-R and QGSJetIII as well as the well-known high-energy physics model Pythia 8.
Particular highlights beyond “classic” air showers are the support for multiple interaction media, including cross-media particle showers crossing from air into dense media and the calculation of radio emission including complex signal propagation effects.
In this presentation, we will discuss the design principles, give an overview of the models, assumptions and algorithms that are employed as well as show case the current capabilities of CORSIKA 8. A brief example of how to obtain the software, run an air shower simulation and inspect the outcome will also be given.

Speaker: Felix Riehn (Technische Universitaet Dortmund (DE))

13:50 From Collider to Cosmic Rays: Pythia 8/Angantyr for Air Shower Simulations in CORSIKA 8

The simulation of extensive air showers is pivotal for advancing our understanding of high-energy cosmic ray interactions in Earth's atmosphere. The CORSIKA 8 framework is being developed as a modern, flexible, and efficient tool for simulating these interactions with a variety of high-energy hadronic models. We present the ongoing implementation and validation of Pythia 8/Angantyr within CORSIKA 8. Pythia 8, successfully used in collider physics, provides a detailed and well-tested treatment of hadronic interactions, while the Angantyr model extends its capabilities to describe heavy-ion collisions in a consistent manner. With the inclusion of Pythia 8, the CORSIKA 8 suite now enables further tuning possibilities, improving the exploration of hadronic interactions in air showers.

In this contribution, we compare the capability of Pythia 8/Angantyr to reproduce fundamental observables of high-energy particle collisions — inelastic cross-sections, multiplicities, and elasticity — to that of several established high-energy interaction models in air shower simulations. We further compare the predictions for key air shower properties, including longitudinal shower development and muon content.

Speaker: Chloé Gaudu (Bergische Universität Wuppertal)

14:05 A new string model for hadron and muon production in extensive air showers

The problem of the excess of muons in extensive air showers (EAS) initiated by very high energy cosmic rays remains an intriguing challenge even for modern upgraded and retuned models of high energy hadron interactions. Collider experiments also demonstrate many indications of some new processes taking place in pp, pA and AA interactions. While some improvements come from the consideration of collective effects originating from high multiplicity of produced partons even in small systems, the standard free string fragmentation model development still has a lot of potential.

In this talk the main features of a new string model of hadronization with the focus on the EAS-related properties are presented. This model is essentially a framework for massive relativistic strings fragmentation. The key features include the proper treatment of strings with non-zero mass, the consideration of the string angular momentum (spin) and its conservation and the new approach to the description and hierarchy of the string-to-hadron transition.

The resulting picture of hadron production features the suppression of scalar mesons production for high-rotation strings. The natural non-symmetrical $\rho^0/\rho^{\pm}$ production that agrees with experimental data is observed. The model also has a natural mechanism for string fragmentation stopping.

Speaker: Roman Nikolaenko (National Nuclear Research University MEPhI)

14:20 Electromagnetic Dissociation at Cosmic-ray Energies

Electromagnetic dissociation (EMD) is a well-known process which has been extensively studied with accelerator beams. On the contrary, the influence of EMD on cosmic-ray propagation in the atmosphere and in the Galaxy is still somewhat unclear. For example, the mass composition is one of the most important ingredients to understand the origin of ultra-high energy cosmic rays. It can be addressed by the measurement of the depth of the maximum of the air shower development (Xmax) and in particular the shower-to-shower fluctuations around its mean. EMD could modified those observables, in particular, for heavy nuclei. Reliable predictions of cross sections, particle yields, and nuclear fragments produced in electromagnetic dissociation interactions at cosmic-ray energies for various projectiles on various targets are presented. The model for predicting EMD cross sections and the subsequent (virtual) photon interactions is briefly described. The model is embedded in the FLUKA code and has already been successfully validated and used at energies from a few GeV/n up to LHC energies. The virtual and real photon interaction models in FLUKA have recently been significantly improved: a brief description of these changes is included. The impact of EMD interactions on cosmic-ray problems is currently being investigated with these tools, and some preliminary results are presented.

Speaker: Dr Alfredo Ferrari (Institute of Astroparticle Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany)

14:35 Improving Air Shower Simulations by Tuning Pythia 8/Angantyr with Accelerator Data

We present a combined tune of the Pythia 8 event generator using accelerator data and evaluate its impact on air shower observables.
Reliable simulations with event generators are essential for particle physics analyses, achievable only through advanced tuning to experimental data. Pythia 8 has emerged as a promising high-energy interaction model for cosmic ray air shower simulations, offering well-documented parameter settings and a user-friendly interface to enable automatic tuning efforts. Using data from collider and fixed-target experiments, we first derive tunes for each domain separately and then simultaneously tune both domains. To achieve this, we define a core set of observables and quantify their dependence on selected parameters. The tuning efforts are based on Bayesian methods, providing a full uncertainty propagation of the parameters to the observables, as well as gradient descent methods.

Results for the impact of a combined tune for the Pythia 8/Angantyr event generator on air shower observables, such as multiplicities at ground level and energy deposit profiles, are given.

Speaker: Michael Windau (Technische Universität Dortmund)

13:20 → 14:50 CRI: radio detection

13:20 Fast and accurate simulation of the radio emission from cosmic ray air showers using template synthesis

In order to interpret the radio data from extensive air showers detectors, we rely on accurate simulations. The state-of-the-art simulation frameworks use Monte-Carlo techniques which pose computational challenges. This is a limiting factor for the next generation of radio arrays, for example the upcoming Square Kilometer Array (SKA), which will have orders of magnitude more antennas than the current arrays. Therefore, we developed template synthesis, a novel, fast and accurate forward model to calculate the radio emission, which achieves the same accuracy as full microscopic simulations in only a fraction of the time. This speeds up the simulation-heavy reconstruction techniques used in Auger and LOFAR by orders of magnitude. Moreover, it can revolutionize the field by allowing efficient production of simulations for more advanced techniques such as interferometry and reconstruction of the longitudinal shape of the shower. Since template synthesis is a fully differentiable model, it can even be used for machine learning or information field theory applications

Our method synthesises the radio emission using a microscopically (Monte-Carlo) simulated origin shower and a set of semi-analytical scaling relations. These relations were extracted from a large set of CoREAS simulations, thus capturing the behaviour of the microscopic models. We divide the atmosphere into slices of constant atmospheric depth and synthesise the emission from each slice separately. In this process we correct for the shower age inside each slice, which we found to be one of the crucial parameters determining the radio emission. The computation time of the synthesis process is negligible compared to the runtime of the microscopic simulation. Crucially, when comparing the synthesised traces to CoREAS simulations, the amplitudes are typically within 5% of each other.

In this contribution we present the complete framework, which can be used for showers of all geometries without any modifications, addressing an important limitation in the previous iterations. It can also account for different experimental conditions, such as the atmosphere and magnetic field, as well as the influence of the air shower geometry. We show that the scaling relations are indeed universal and can be used in many different conditions, without losing its accuracy.

Since the template synthesis framework is now ready to be used in analyses, we are happy to make it available to the community as a Python package. It will be made public during the conference, complete with the necessary parameters to use it.

Speaker: Mitja Desmet

13:35 High Energy Cosmic Ray reconstructions using the surface stations of the Radar Echo Telescope (RET)

The Radar Echo Telescope for Cosmic Rays (RET-CR) is a prototype experiment for the future neutrino detector, the Radar Echo Telescope for Neutrinos (RET-N). It is deployed at Summit Station in Greenland, with a full data-taking run conducted in the summer of 2024.

This experiment utilises the radar technique to search for an in-ice secondary cascade produced when the core of a high-energy cosmic ray air shower propagates into the high-altitude ice sheet.

RET-CR, along with the in-ice radar system, includes five surface stations, each equipped with IceTop scintillator panels and a SKALA radio antenna. These surface stations trigger on incoming cosmic ray air showers and independently reconstruct the arrival direction, primary energy, and core position. The radar search for secondary in-ice cascades and the properties obtained will be validated against the measurements from the surface stations.

This contribution focuses on the air shower reconstruction of cosmic ray parameters using the particle data.

Speaker: Krishna Nivedita Gopinath (Radboud University)

13:50 Revisiting the Radio LDF: a strong electric field amplitude dependence on $X_{max}$

In this work we show that there is a strong dependence of the radio lateral distribution function (LDF) electric field amplitudes at ground level on the position of the shower maximum ($X_{max}$) in the atmosphere, even when accounting for differences in the electromagnetic (EM) energy of the showers. This $X_{max}$ dependence can be explained in terms of two competing effects on the measured electric field: A scaling with distance from $X_{max}$ to the core at ground, and a scaling with air density at $X_{max}$. At low zenith angles, the distance scaling dominates, leading to overall larger measured electric fields as $X_{max}$ increases. At higher zenith angles, i.e., lower densities, the stronger deflections due to the Lorentz force induce large time delays between the particle tracks, decreasing the coherence of emission. This loss of coherence is highly dependent on the strength of the geomagnetic field and can slow down, or even reverse, the expected increase of the radio emission with decreasing air density. This dependence of the radio amplitude on $X_{max}$/composition could be used to directly infer the cosmic ray primary composition on an event-by-event basis. It could also induce a possible $X_{max}$/composition bias on shower EM energy reconstruction methods.

Speaker: Dr Washington Carvalho Jr. (Faculty of Physics, University of Warsaw)

14:05 Backtracking radio signals for the $X_\rm {max}$ measurement of extensive air showers: A new approach

Precise measurements of the composition of cosmic rays in the energy range of  $10^{17}-10^{18}\,$eV could provide crucial insights into the long-standing questions about the origin and acceleration of these particles. Ground-based experiments typically rely on determining the position of the extensive air shower maximum ($X_\rm {max}$) to identify the type of cosmic ray particle. One effective method for determining $X_\rm {max}$ is by analyzing the radio emission produced by these air showers. This approach offers several advantages, including continuous operation and a higher duty cycle compared to fluorescence telescopes, which are limited by weather conditions and lunar phases. However, conventional radio-based methods often involve computationally intensive Monte Carlo simulations, or rely on pre-calculated parameterizations derived from simulations. In this contribution, we present a new method which is highly efficient and has the potential to reconstruct $X_\rm{max}$ with very minimal input from simulations. This method reconstructs the radio emission profile of air showers by backtracking the radio signals recorded by a ground-based antenna array, considering that the signal received by each antenna travels perpendicular to the radio wavefront. By analyzing simulated proton and iron showers in the $\rm 10^{17}-10^{18}\,$eV range, this study reveals a strong correlation between the radio emission profiles in the 20–80 MHz frequency band, and the longitudinal profile of the air shower.

Speaker: Dr Jhansi Vuta (Department of Astroparticle Physics, Institute of Physics of the Czech Academy of Sciences, 18200 Prague, Czech Republic.)

14:20 Holistic air shower reconstruction with probabilistic forward modeling for LOFAR

The Low Frequency Array (LOFAR) has been measuring cosmic rays for over a decade. Its dense core of antenna fields makes it an ideal tool for studying the radio emission of extensive air showers, sensitive to energies between $10^{16.5}$ eV and $10^{18}$ eV. Each air shower is recorded using a small particle detector array and hundreds of antennas. The current state-of-the-art method for reconstructing properties such as the shower maximum ($X_\text{max}$) relies on a $\chi^2$ fit of the measured electric field fluence data to a range of simulations and achieves the highest precision to date. However, reconstructing on the fluence-level, it does not fully utilize all available information from the data, the full time-dependent electric field, and is computationally intensive.

We present the current state of development of a new, holistic approach using Information Field Theory (IFT) that incorporates all available information within the data, and combines both particle detector and antenna data. This method uses probabilistic forward modeling of the radio signal and offers a physics-informed, simulation-independent reconstruction. Additionally, by treating the signal as a random field, IFT can simultanously provide uncertainty quantification.
The reconstruction takes the voltage traces and antenna positions and will yield time dependent electric fields at any ground position of the shower footprint, along with reconstruction parameters such as the depth of shower maximum ($X_\text{max}$), the cosmic ray energy $E$ and the direction of the cosmic ray as the forward model is dependent on these parameters.

Speaker: Karen Terveer

14:35 Analytical description of the radio Cherenkov cone

Radio emissions from extensive air showers (EAS) provide a valuable tool for detecting ultra-high-energy (UHE) astroparticles. In this context, several radio arrays focus on detecting highly inclined EAS, as this enables the observation of Earth-skimming UHE neutrinos, in addition to cosmic rays and gamma rays.
The reconstruction of such inclined events relies heavily on a thorough understanding of the radio features observed on the ground, with the Cherenkov cone being one of the most prominent. In this study, building upon previous work on vertical air showers, we show that the Cherenkov cone for inclined air shower can be accurately described using basic propagation principles. Furthermore, we have developed an analytical model that computes the expected opening angles of the cone and reproduces the asymmetry effects observed in simulations. The good accuracy of these computations has the potential to enhance current reconstruction methods and pave the way for the development of new ones.

Speaker: Valentin DECOENE (Subatech)

13:20 → 14:50 DM: direct detection

13:20 Searching for Dark Matter and Rare Events with XENONnT

The XENONnT experiment is a dual-phase xenon time projection chamber (TPC) designed for the direct detection of dark matter. It has been operating at the INFN Laboratori Nazionali del Gran Sasso (Italy) since 2020, with a total xenon mass of 8.6 tonnes. During the first two science runs, XENONnT collected data with a total exposure of about 3.5 tonne-years. Thanks to its extremely low background and low-energy threshold, the experiment is sensitive to potential dark matter candidates as well as other rare interactions. A significant achievement demonstrating the detector's capabilities is the first measurement of nuclear recoils from solar $^8$B neutrinos via coherent elastic neutrino-nucleus scattering (CEνNS). In this talk, the current status and latest results from XENONnT will be presented.

Speaker: Dr Emanuele Angelino

13:35 Latest results and prospects of the SENSEI experiment.

SENSEI (Sub-Electron Noise Skipper Experimental Instrument) is the first experiment to implement silicon skipper CCDs to search for dark matter. Skipper-CCDs can resolve single electrons in each of millions of pixels, which allows for the low energy threshold required to detect sub-GeV dark matter interacting with electrons. SENSEI recently measured the lowest event rates containing one electron in silicon detectors, resulting in world-leading sensitivity. In this talk, we present the latest results from two science runs at SNOLAB as well as the future prospects for SENSEI.

Speaker: Ana Martina Botti (Fermilab)

13:50 PandaX-4T Reaches As A Multi-purpose LXe Experiment

The PandaX-4T experiment, a multi-ton scale liquid xenon detector, has achieved leading-edge physical results across multiple research targets with its latest accumulated exposure. Leveraging its unprecedented sensitivity and low background capabilities, PandaX-4T has conducted extensive searches for Weakly Interacting Massive Particles (WIMPs) and other exotic DM candidates, setting stringent constraints on dark matter interactions. Additionally, the experiment has explored exotic dark matter models, providing new insights into beyond-the-Standard-Model scenarios. PandaX-4T has also made significant contributions to the study of Coherent Elastic Neutrino-Nucleus Scattering (CEvNS), enhancing our understanding of neutrino properties. Furthermore, the experiment has advanced the search for neutrinoless double-beta decay (0νββ), a key process for probing the nature of neutrino masses and lepton number violation. These achievements demonstrate PandaX-4T's pivotal role in pushing the boundaries of particle physics and dark matter research.

Speaker: Yi Tao (Sun Yat-sen University)

14:05 Light WIMP search with the NEWS-G experiment

The NEWS-G experiment uses spherical proportional counters (SPC) to probe for low mass dark matter. An SPC is a metallic sphere filled with gas with a high-voltage anode at its centre producing a radial electric field. The interaction between a dark matter particle and a nucleus can cause ionization of the gas, which leads to an electron avalanche near the anode and a detectable signal.

The latest NEWS-G detector, S-140, is a copper sphere of 140 cm of diameter, which took 10 days of data with methane at the LSM, producing world-leading WIMP-proton spin-dependent limits. The detector is now taking data at SNOLAB with various gases including neon and helium. The LSM and SNOLAB campaigns have also shed light on new challenges to overcome in order to maximize the capabilities of the detector. This in turn led to the development of interesting new techniques in terms of characterization, discrimination and reduction of backgrounds.

This talk will describe the NEWS-G experiment, present the latest results from the LSM data and discuss the progress on data taking and analysis at SNOLAB.

Speaker: Jean-Marie Coquillat (Queen's University, Canada)

14:20 The Darkside-20k experiment

DarkSide-20k is a next-generation multi-ton dark matter experiment currently being built at the INFN Gran Sasso National Laboratory (LNGS). Building on the success of the DarkSide-50 detector, which has been in operation since 2015, DarkSide-20k will feature a dual-phase Liquid Argon Time Projection Chamber (TPC) with a 20-tonne fiducial mass (50-tonne active), designed to achieve unprecedented sensitivity in direct dark matter detection. The experiment incorporates advanced technologies essential for large-scale dark matter searches, including ultra-low-radioactivity underground argon (depleted of ³⁹Ar) and large-area cryogenic Silicon Photomultipliers with custom, compact electronics for light detection. Additionally, a global radiopurity assay program is in place to ensure minimal background contamination in construction materials. The TPC will be housed inside a membrane cryostat containing over 700 tonnes of liquid argon and surrounded by an active neutron veto. DarkSide-20k aims to achieve a WIMP-nucleon cross-section exclusion sensitivity of 7.4×10⁻⁴⁸ cm² for a 1 TeV/c² WIMP over a 200 tonne-year exposure, with no instrumental backgrounds. This presentation will provide updates on the ongoing construction, prototype testing, and validation of the detector design through Monte Carlo simulations.

Speaker: Oscar Alejandro Taborda Pulgarin (Gran Sasso Science Institute (GSSI))

14:35 Latest results and future prospects of DEAP-3600

The DEAP-3600 experiment is a direct dark matter detection experiment located 2 km deep underground at SNOLAB, Canada. 3.3 tonnes of liquid argon contained in an acrylic vessel instrumented with 255 PMTs are used for this experiment. It aims to measure nuclear recoil of argon caused by weakly interacting massive particles (WIMPs), a potential dark matter candidate. Since 2019, DEAP-3600 has held the most stringent exclusion limit on WIMP-nucleon interaction cross-section in argon above 20 GeV mass scale.

New measurements of scintillation quenching of alpha particles and the half-life of 39Ar using DEAP-3600 have been concluded. Improvements on position reconstruction of the detector have been made. A profile likelihood ratio analysis of data is underway to enhance constraints on WIMPs. A dedicated search for solar neutrino absorption in argon is also nearing completion. An upgrade of the experiment to mitigate backgrounds coming from a shadowed region of the detector and possibly from dust in the liquid argon is in its final phase. A new data-taking campaign is set to commence soon.

This contribution will provide a comprehensive overview of DEAP-3600, summarizing the current status, the latest results, and the future prospects of the experiment.

Speaker: Abhijit Garai (Queen's University)

13:20 → 14:50 GA: space experiments

13:20 GRAINE Project: High-resolution Imaging and Polarization Measurement of Sub-GeV/GeV Gamma Rays with Balloon-borne Emulsion Telescopes

The Large Area Telescope onboard the Fermi Gamma-ray Space Telescope (Fermi-LAT) has surveyed the sub-GeV/GeV gamma-ray sky and achieved high statistics measurements since 2008. However, observation at low galactic latitudes remains difficult owing to the lack of the angular resolution, and new issues following the operation of Fermi-LAT have arisen.
We devised a precise gamma-ray observation project, Gamma-Ray Astro-Imager with Nuclear Emulsion (GRAINE), using balloon-borne emulsion gamma-ray telescopes to realize high angular resolution, polarization-sensitive, and large-aperture observations in the 0.01–100 GeV energy region. The main detector of the telescope, the nuclear emulsion, is a device that can track charged particles with sub-micron accuracy, and by measuring the angle of electron pair tracks and the emission azimuthal angle directly below the gamma-ray conversion point, it has a high angular resolution of 0.1 degrees in the 1 GeV band and the ability to measure polarization in the sub-GeV band. By combining the nuclear emulsion with a time stamper and launching it on a balloon, it is possible to achieve precision observations that would not be possible with satellite projects.
GRAINE's initial targets are high-angular-resolution observations of the Fermi Galactic Center GeV Excess and the first polarization measurement of the Vela pulsar in the sub-GeV band by repeatedly launching balloons from Australia. In the 3rd balloon experiment conducted in 2018, imaging observations of the Vela pulsar in the 100 MeV band were achieved with the world's highest resolution using a small-size emulsion telescope.
This talk comprehensively reports the latest observational results from the Vela pulsar and the Galactic center region from the 4th balloon experiment (conducted in April 2023) that launched a telescope with a 2.5-m$^2$ aperture area 6 times larger than the previous experiment, as well as the technical developments for high-angular resolution and polarization measurements using an emulsion telescope, and the preparation status towards further scientific observations using larger telescopes and long-duration balloon flights.

Speaker: Hiroki Rokujo (Nagoya University (JP))

13:35 GRAINE2023: Sub-GeV/GeV gamma-ray observation with a high angular resolution by the balloon borne emulsion telescope

The GRAINE project observes cosmic gamma-rays, using a balloon-borne emulsion-film-based telescope in 10MeV-100GeV energy band. The high spatial resolution (<1μm) of the emulsion films makes high angular resolution (5◦ at 100 MeV and 0.8◦ at 1 GeV) and polarization sensitivity for the gamma-ray. One of our target is Galactic center region. A few GeV Gamma-rays are expected to be produced via the annihilation of dark matters in there, but the observation is difficult due to the contamination of diffuse gamma-ray background. The high angular resolution makes low contamination of the background and our observation may bring new insights.
In the GRAINE project, we conducted 4th balloon experiment (GRAINE2023) in 2023. Its aperture area of the emulsion gamma-ray telescope was 2.5 m^2. The Galactic center region was observed for the first time with the emulsion gamma-ray telescope in the GRAINE2023. We will report the preliminary results in GRAINE2023 for the brightest gamma-ray source in this energy band (Vela pulsar) and the Galactic center region.

Speaker: Yuya Nakamura

13:50 GeV Gamma-Ray Detection Performance of the Nuclear Emulsion Telescope in the GRAINE 2023 Balloon Experiment

We are advancing precise observations of cosmic gamma rays in the sub-GeV/GeV energy range using a large-scale nuclear emulsion telescope with high angular resolution (0.1° at 1 GeV), deployed on a balloon. We conducted balloon experiments in 2011, 2015, 2018, and 2023. In 2018, we achieved the first detection of an astronomical gamma-ray source and imaged the Vela pulsar with the worldʼs highest angular resolution in the sub-GeV region. In April 2023, we successfully conducted a 27-hour balloon flight during which the Vela pulsar and the region around the Galactic center were observed (GRAINE 2023).
The nuclear emulsion telescope consists of a converter, a time stamper, and an attitude monitor. The converter section is a stacked structure with nuclear emulsion films, capturing electrons and positrons from gamma rays. The high angular resolution of nuclear emulsion films enables precise determination of gamma-ray directions and momentum measurement through multiple Coulomb scattering.
We are developing new techniques for the detection of high-energy (>GeV) gamma rays. In the nuclear emulsion telescope, detection of high-energy gamma rays is challenging because the two tracks produced by pair production have an opening angle too narrow to be separated. Furthermore, the small scattering of the produced electrons and positrons makes it difficult to reconstruct the gamma-ray energy from momentum measurements. We introduce a new method to improve gamma-ray detection and momentum measurement for the nuclear emulsion telescope.
This presentation will report the current analysis of the GRAINE 2023 converter section and the new gamma-ray selection method under development.

Speaker: Mr Ikuya Usuda (Nagoya University)

14:05 The Transient High-Energy Sky and Early Universe Surveyor (THESEUS)

The Transient High-Energy Sky and Early Universe Surveyor (THESEUS) is a mission concept developed by a large European collaboration under study by ESA since2018 and currently one of the three candidates M7 mission for a launch in the late '30s. THESEUS aims to fully exploit Gamma-Ray Bursts for investigating the early Universe and as key phenomena for multi-messenger astrophysics. By providing an unprecedented combination ofX-/gamma-ray monitors, on-board IR telescope and spacecraft autonomous fast slewing capabilities,THESEUS will be a wonderful machine for the
detection, multi-wavelength characterization and redshift measurement of any kind of GRBs and many classes of X-ray transients, including high-redshift GRBs for cosmology (pop-III stars, cosmic reionization, SFR and metallicity evolution up to the “cosmic dawn”) and electromagnetic counterparts to sources of gravitational waves, especially short GRBs, possible soft X-ray emission and KN emission from NS-NS / NS-BHmergers. Moreover, THESEUS will enable extreme and fundamental physics through unprecedented breakthrough measurements of GRB prompt and afterglow emission, as well as the detection and multi-eavelength characterization of many classes of high-energy transients. In all thses respects, THESEUS will thus provide an ideal synergy with the very large astronomical facilitiesof the future working in the e.m. (e.g., ELT, CTA, SKA, Athena) and multi-messenger (e.g., Einstein Telescope, Cosmic Explorer, km3NET).

Speaker: Dr Lorenzo Amati (INAF - OAS Bologna)

14:20 The Cosmic X-ray Background Explorer (CXBe) Project

The Cosmic X-ray Background (CXB) traces the integrated energy released by black hole accretion across cosmic history, primarily from Active Galactic Nuclei (AGN). The Cosmic X-ray Background Explorer (CXBe) aims to measure the CXB spectrum with unprecedented ~1% accuracy, an order of magnitude improvement over the current ~15-20% uncertainties. This advancement will refine synthesis models and enhance our understanding of AGN populations, particularly regarding their obscuration and X-ray reflection properties. The CXBe mission has been endorsed for deployment on the Chinese Space Station (CSS) and recently secured funding for Phase A/B1 prototype studies. Two key system requirements will be addressed: (1) developing a long-lifetime rotating system capable of stable multi-year operation, and (2) achieving quasi-absolute detector calibration at the ~1% level. These efforts, supported by Swiss contributions and in collaboration with Chinese partners, will accelerate mission development, with a CSS launch targeted within this decade. In this presentation, I will introduce CXBe's science objectives, outline the current status, and discuss its prospects for the coming years.

Speaker: Hancheng Li

14:35 Solar Flare Hard X-ray Polarimetry with the CUbesat Solar Polarimeter (CUSP) mission

The CUbesat Solar Polarimeter (CUSP) project is a CubeSat mission planned for a launch in low-Eart orbit and aimed to measure the linear polarization of solar flares in the hard X-ray band by means of a Compton scattering polarimeter. CUSP will allow to study the magnetic reconnection and particle acceleration in the flaring magnetic structures of our star. CUSP is a project in the framework of the Alcor Program of the Italian Space Agency aimed to develop new CubeSat missions. It is undergoing a 12-months Phase B that started last December.

The Compton polarimeter on-board CUSP is composed of two acquisition chains based on plastic scintillators read out by Multi-Anode PhotoMultiplier Tubes for the scatterer part and GAGG crystals coupled to Avalanche PhotoDiodes for the absorbers. An event coincident between the two readout scheme will lead to a measurement of the incoming X-ray's azimuthal scattering angle, linked to the polarization of the solar flare in a statistical manner. The current status of the CUSP mission design, mission analysis and payload scientific performance will be reported. The latter will be discussed based on preliminary laboratory results obtained in parallel to Geant4 simulations.

Speaker: Dr Nicolas De Angelis (INAF-IAPS)

13:20 → 14:50 NU: experimental & next generation

13:20 The KM3NeT ultra-high-energy event

Even if in a partial detector configuration, a neutrino event of exceptional energy (about 220 PeV) was detected with the KM3NeT-ARCA detector [Nature 638, 376–382 (2025)]. This ultra-high-energy event lies in an unexplored energy range where neutrinos have been predicted but never observed until now.
At the time of the detection, on February 13 2023, the ARCA detector consisted in 21 detection lines, about 10% of the total volume of the full planned detector.
Several hypotheses on the possible origin of this event have been analyzed so far by the KM3NeT collaboration, but a clear indication of its possible origin has not been found.
In this contribution, the details of the event energy and direction reconstruction together with the investigated hypotheses on its origin will be reported.

Speaker: Mathieu Lamoureux (UCLouvain)

13:35 A search for extremely-high-energy neutrinos with IceCube and implications for the ultra-high-energy cosmic-ray proton fraction

When ultra-high-energy cosmic rays (UHECRs) interact with ambient photon backgrounds, a flux of extremely-high-energy (EHE), so-called cosmogenic, neutrinos is produced.
The observation of these neutrinos with IceCube can probe the nature of UHECRs. We present a search for EHE neutrinos using 12.6 years of IceCube data. The non-observation of neutrinos with energies $>~10 \, \mathrm{PeV}$ constrains the all-flavor neutrino flux at $~1 \, \mathrm{EeV}$ to a level of $E^2 \Phi_{\nu_e + \nu_\mu + \nu_\tau} \simeq 10^{-8} \, \mathrm{GeV} \, / \, \mathrm{cm}^2 \, / \, \mathrm{s} \, / \, \mathrm{sr}$, the most stringent limit to date.
This constrains the proton fraction in UHECRs of energy above $30 \, \mathrm{EeV}$ to be $<70\%$ if the evolution of the UHECR sources is similar to the star formation rate. Our analysis circumvents uncertainties associated with hadronic interaction models in studies of UHECR air showers, which also suggest a heavy composition at such energies.

Speaker: Maximilian Meier (ICEHAP, Chiba University)

13:50 Ultra-high energy neutrino flux limit from Baikal-GVD

Baikal-GVD is a cubic-kilometer scale underwater neutrino telescope currently under construction in Lake Baikal. The detector layout is optimized for the measurement of astrophysical neutrinos with energies of ~100 TeV and above. Recently, a similar neutrino telescope, KM3NeT, detected a unique, ultra-high energy neutrino event, KM3-230213A. This case proves the possibility of detecting extraterrestrial neutrinos with tremendous energies and allows us to expect to observe similar events at Baikal-GVD. Here we present an upper limit on neutrino flux obtained in Baikal-GVD for the energy range around 100 PeV.

Speaker: Maksim Sorokovikov

14:05 Status of the Trinity PeV Neutrino Observatory

The Trinity Neutrino Observatory aims to detect tau neutrinos in the energy range of 1 PeV to 10 EeV. We are developing the observatory in three stages. The first stage, known as the Trinity Demonstrator, was deployed in Fall 2023. The Demonstrator serves as a pathfinder for the full observatory and will inform the design of the first Trinity Telescope. In this presentation, I will discuss the status and initial results of the Trinity Demonstrator, as well as provide an update on the development of the next stage, Trinity One, which will be a leading instrument for observing neutrino point sources.

Speaker: Sofia Stepanoff (Georgia Institute of Technology)

14:20 Search for Ultra-High-Energy Neutrinos at the Pierre Auger Observatory: New Triggers, Methods, and Constraints

The Pierre Auger Observatory has the capability to identify neutrino-induced extensive air showers above $10^{17}\,$eV by using its large Surface Detector (SD) array. Data from the Observatory have been used to set some of the most stringent upper limits to the neutrino flux in the ultra-high energy (UHE) range. The data have also been used for follow-up detection of transient events in the context of multi-messenger astrophysics. In mid-2013, two additional SD triggers (Time-over-Threshold-deconvolved (ToTd) and Multiplicity-of-Positive Steps (MoPS)) were shown to increase the detection capability for the neutrino-induced air showers in the energy regime below $10^{19}\,$eV by a factor of 5-10.
This contribution will give an overview of the ongoing work regarding the searches for UHE neutrinos at the Pierre Auger Observatory. The impact of the ToTd and MoPS triggers for neutrino search in the zenith angle range of $60^{\circ} < \theta < 75^{\circ}$ is discussed. A novel neutrino identification method, which integrates these triggers, is applied to observational data to look for neutrino-like events using a blind search strategy. New constraints to point-like sources of UHE neutrinos will be presented for the angular range explored.

Speaker: Srijan Sehgal

14:35 First Array-Wide Search for Diffuse UHE Neutrinos with the Askaryan Radio Array

The Askaryan Radio Array (ARA) is an ultrahigh energy (UHE) neutrino detector at the South Pole, designed to search for radio pulses emitted by neutrino-initiated particle showers in ice. ARA consists of an array of five autonomous stations with 2 km spacing. Each station consists of 16 radio antennas embedded ~200 m deep in the ice that are sensitive to either vertically- or horizontally-polarized signals. Radio arrays like ARA represent a cost-efficient means of achieving the enormous detection O(10 km$^3$) volumes necessary for UHE neutrino detection. This contribution presents the current status of the first-ever array-wide search for UHE neutrinos, leveraging ARA’s unprecedented ~28 station-years of livetime. This search will have the best sensitivity of any radio-based neutrino detector up to 1000 EeV, sufficient to probe the 220 PeV flux inferred from KM3-230213A. Importantly, this study demonstrates the feasibility of array-wide neutrino searches, which are necessary for next-generation detectors, like RNO-G (35 stations planned) and IceCube-Gen2 Radio (361 stations proposed), to achieve their design sensitivity. We discuss the progress towards a fully analyzed sample and improvements to ARA’s detector characterization and analysis sensitivity.

Speaker: Marco Muzio

13:20 → 14:50 SH: Solar modulation

13:20 study of the solar modulation of the time-dependent fluxes of antiprotons in the AMS-02 era

The spectra of galactic cosmic rays (GCRs) contain crucial information about their origin and propagation through the interstellar medium. When GCRs reach Earth, they are significantly influenced by the solar wind and the heliospheric magnetic field, a phenomenon known as solar modulation. This effect introduces time-dependent variations in GCR fluxes. The AMS-02 experiment has released time-dependent flux data for protons, electrons, and positrons, revealing clear correlations with solar modulation. Studies suggest that cosmic rays with the same charge, such as protons and helium nuclei, exhibit similar/same solar modulation parameters. In this work, we derive the LIS for protons and positrons under the assumption of a common solar modulation potential, using data from Voyager 1 and a 7-year average from AMS-02. Similarly, the LIS for antiprotons and electrons is derived by assuming they are governed by a separate solar modulation potential. We demonstrate that the time-dependent fluxes of positrons and protons can be accurately modeled using the same set of solar modulation parameters within a modified force-field approximation framework. Based on this, we predict the time-dependent fluxes of antiprotons using the corresponding electron flux data. The latest publication from the AMS Collaboration demonstrate remarkable consistency with our theoretical predictions within their 1σ confidence interval.

Speaker: Cheng Rui Zhu

13:35 Aspects of antiproton modulation in the heliosphere

Unlike cosmic ray protons, the antiproton local interstellar spectrum (LIS) was not observed by the Voyager missions when crossing the heliopause into the interstellar medium. As a result, the shape and values of the antiproton LIS at lower energies (rigidities) are still unknown. The recent AMS-02 observations, averaged over a Bartel rotation (27 days), confirmed earlier model predictions that cosmic ray antiprotons are relatively less sensitive to solar cycle related changes in the transport parameters at lower rigidities, which is in sharp contrast to protons. In this study, the previously established set of proton modulation parameters that reproduced PAMELA and AMS-02 proton observations between 2006 and 2022 is applied in our physics-based 3D-drift numerical model to simulate modulated antiproton spectra over the same period. This way the only differences between galactic protons and antiprotons simulations remain their LISs and the sign of their charges. This study will illustrate and discuss peculiar aspects of antiproton modulation. It will highlight how the shape of its LIS at lower rigidities intriguingly resembles the shape of modulated spectra deep inside the heliosphere as influenced by adiabatic energy losses.

Speaker: Dr Donald Ngobeni (1. Centre for Space Research, North-West University, Potchefstroom, South Africa. 2. Department of Physical and Earth Sciences, Sol Plaatje University, Kimberley, South Africa)

13:50 Rigidity spectrum of cosmic-ray anisotropy observed by Global Muon Detector Network (GMDN)

Anisotropy of galactic cosmic-rays (GCRs) represents their momentum-space distribution in the interplanetary plasma, playing a key role in revealing the solar modulation of GCRs. The Global Muon Detector Network (GMDN; http://hdl.handle.net/10091/0002001448) has been a unique means to observe the anisotropy, thanks to its excellent angular resolution, angular acceptance, and statistics. However, quantitative analysis of rigidity dependence of the anisotropy has been difficult because of the broad rigidity responses of such ground-based cosmic-ray counters. To overcome this situation and derive the rigidity dependence from geomagnetic- and atmospheric-effect differences in the network's directional channels, we are developing a new analysis method based on the Bayesian estimation approach. The Gaussian process is introduced as a prior distribution of the Bayesian estimation. It allows us to confine the smoothness of the rigidity spectrum, which is required to derive the spectrum from the broad rigidity responses, while being tolerant of spectrum shapes without assuming any analytical function. A focused analysis of the North-South (NS) anisotropy demonstrates the usefulness of this new method and revealed its rigidity spectrum on yearly basis for the first time (M. Kozai et al., 2024; https://doi.org/10.3847/1538-4357/ad8577). We are now attempting to generalize this Bayesian estimation approach to three-dimensional anisotropy and will report on its application to short-term events, such as Forbush decreases.

Speaker: Masayoshi Kozai (PEDSC/ROIS-DS)

14:05 Scaler data from the Pierre Auger Observatory as a proxy of solar activity

Solar activity variations strongly impact the modulation of the flux of low-energy Galactic Cosmic Rays (GCRs) reaching the Earth. The secondary particles, which originate from the interaction of GCRs with the atmosphere, can be revealed by an array of ground detectors. We show that the low-threshold rate (scaler) time series recorded over 16 years of operation by the surface detectors of the Pierre Auger Observatory in Malargüe (Argentina) strongly reflects solar activity and can be considered as a new proxy of solar variability. To achieve this result, we apply advanced spectral methods to this time series and to the classical solar sunspot number and sunspot area series, as well as to different heliospheric magnetic field series measured by NASA's Advanced Composition Explorer. We detect and compare highly significant variations with periods ranging from the decadal to the daily scale and identify the origin of each variability mode. In conclusion, we show that the Auger scaler data, thanks to the very low noise level and high statistical significance related to the very high count rates (∼10^^6 counts per second), allow for a thorough and detailed investigation of the GCR flux variations in the heliosphere.

Speaker: Prof. Carla Taricco (Department of Physics - University of Torino (Italy))

14:20 Modeling the heliospheric modulation of cosmic-ray particles and antiparticles in light of new multichannel data from AMS-02 in space.

Understanding the heliospheric modulation of galactic cosmic rays is essential for studying the acceleration and propagation processes of these particles, as well as for establishing models of radiation exposure and associated risks in space missions. Here we present our efforts in the development of an effective data-driven model describing the time- and energy-dependent solar modulation effects for cosmic-ray protons, nuclei, and their antiparticles. In particular, we present our numerical description of the transport mechanisms of charged particles in the heliospheric turbulence, their relationships with observations of solar activity, our subsequent evaluations of radiation doses in the low-Earth orbit. We discuss the role of the recent multichannel data from the AMS-02 experiment in constraining the model and revealing important details of the solar modulation phenomenon.

Speaker: Nicola Tomassetti (Perugia University & INFN- Perugia)

14:35 Deep Learning the Forecast of Galactic Cosmic-Ray Spectra

We introduce a novel deep learning framework based on long short-term memory networks to predict galactic cosmic-ray spectra on a one-day-ahead basis by leveraging historical solar activity data, overcoming limitations inherent in traditional transport models. By flexibly incorporating multiple solar parameters, such as the heliospheric magnetic field, solar wind speed, and sunspot numbers, the model achieves accurate short-term and long-term predictions of cosmic-ray flux. The addition of historical cosmic-ray flux data significantly enhances prediction accuracy, allowing the model to capture complex dependencies between past and future flux variations. Additionally, the model reliably predicts full cosmic-ray spectra for different particle species, enhancing its utility for comprehensive space weather forecasting. Our approach offers a scalable, data-driven alternative to traditional physics-based methods, ensuring robust daily and long-term forecasts. This work opens avenues for advanced models that can integrate broader observational data, with significant implications for space weather monitoring and mission planning.

[1] Yi-Lun Du, Xiaojian Song, and Xi Luo, 2025 ApJL 978 L36

Speaker: Prof. Yi-Lun Du (Shandong Institute of Advanced Technology)

14:50 → 15:20 Coffee

15:20 → 16:50 CRD: instruments

15:20 The TIGERISS Galactic Cosmic Ray Detector

The Trans-Iron Galactic Element Recorder for the International Space Station (TIGERISS) is a Galactic Cosmic Ray (GCR) detector being developed as a NASA Astrophysics Pioneers mission to launch to the ISS in 2027. TIGERISS has been assigned the Starboard Overhead X-Direction (SOX) location on the Columbus External Payload Facility (EPF) of the ISS. It will be the first instrument to measure the GCR elemental abundances from $_{5}$B to $_{82}$Pb over $\sim$400 MeV/nucleon to $\sim$10 GeV/nucleon with single element resolution. TIGERISS builds on the heritage of the TIGER and SuperTIGER stratospheric balloon-borne experiments flown from Antarctica and uses the proven combination of ionization (dE/dx) detectors with acrylic and silica aerogel Cherenkov-light-radiator ($\propto$$\beta$) detectors for charge and energy measurements. It improves on the predecessor instruments by using silicon strip detectors (SSDs) in place of both scintillating fiber hodoscopes for track reconstruction and large area scintillator detectors for dE/dx measurement and the instrument trigger. The superior charge resolution ($\sigma_{Z}$ < 0.25) and signal linearity over the full dynamic range of the TIGERISS SSDs have been demonstrated in CERN beam tests. TIGERISS will also use silicon photomultipliers (SiPMs) instead of photomultiplier tubes (PMTs) to forego the need for high voltage (HV) and for the more compact Cherenkov detector readout needed to maximize the instrument geometry within the payload envelope. This enables an instrument geometry factor of 1.21 m$^2$sr that will allow TIGERISS in one year to observe GCR statistics comparable to those observed in the first 55-day SuperTIGER flight over their common measurement range without the systematics from atmospheric propagation corrections. With the possibility of extended observations, TIGERISS will test models of GCR origins, including their source environments and acceleration mechanisms. In measuring GCRs over nearly the entirety of the s-process and r-process (slow and rapid) neutron capture processes and the rp-process rapid-proton capture process of heavy-element nucleosynthesis, TIGERISS will make a significant contribution to the wider multi-messenger effort to determine the relative contributions of supernovae (SNe) and Neutron Star Merger (NSM) events.

Speaker: Brian Rauch

15:35 Much-needed high-Z (p,X) cross sections for TIGERISS and other cosmic-ray missions

Great advances are happening in our understanding of our Galaxy and its physical phenomena, courtesy of missions such as TIGERISS (Trans-Iron Galactic Element Recorder on the International Space Station), which will be the first single instrument to look at elemental abundances spanning B to Pb. However, the accurate interpretation of these advanced observational data is contingent upon accurate cross-section data, which are currently quite lacking and inadequate. There are gaps in data and unreliable measurements abound, and there have been very little drive to address these concerns, especially for proton spallation (p,X) cross-sections in high-Z and high-energy regions, which are imperative to study cosmic ray origins. To that end, our team at NASA Goddard has established a collaboration with various institutions to perform a series of cross-section experiments for the reaction channels of utmost importance. The first of these experiments was performed in March 2024, at Brookhaven National Lab. Proton beams with energies between 0.2 to 2.5 GeV were irradiated upon a natural Cr and a monoisotopic Mn target, and the cross sections of several natCr(p,X) and 55Mn(p,X) reactions are currently being determined, using known gamma-ray lines of unstable daughter products. The second in this series is a planned experiment at FRIB, where we are currently setting up a 52Cr primary beam, for bombardment on a liquid Hydrogen target to study 52Cr(p,X) reactions. Our team has also become limited members of the NA61 collaboration, who performed a proton-spallation experiment at CERN, where high-Z isotopic beams up to Si were incident on a CH2 target. We will report upon how these experiments will help TIGERISS, and our future plans in this endeavour.

Speaker: Priyarshini Ghosh (NASA-Natl. Aeronaut. & Space Admin. (US))

15:50 MINI HYBRID NOVEL COSMIC RAY DETECTOR

Normally, cosmic ray detectors are based on materials where ions or photons are generated as a result of the passage of radiation through the materials, and ions or photons are collected to detect, study, and measure the incident radiation. To combine in one technique, both the ion and photon collection, we planned, designed, constructed, and used a small cosmic ray detector based on one $10 \:cm \times 10 \:cm \times 10 \:cm$ Aluminum block with four ion channels detection of ions by four pairs of collectors inside a high electric field, like a time projection chamber and two photonic channels detection of photons by a couple of photomultiplier tubes. We looked for correlated events between both type of channels. We simulated the whole detector based on the block of Aluminum using CERN GEANT4, and based on similar block of scintillator acrylic, and based on similar volume of air. We got satisfactory results. We present technical details of this cosmic ray detector, and some preliminary physics results.

Speaker: Misael Perez Sierra (Laboratorio Internacional de Partículas Elementales, Departamento de Física, DCeI, CL. UGTO)

16:05 Sensitivity studies and technological advancements for balloon-borne demonstrators of direct antimatter detection

The development of next-generation cosmic-ray spectrometers requires a robust technological foundation to enable precise and high-sensitivity measurements. This work explores the technological advancements in superconducting magnets and pixel silicon-based trackers, focusing on their application in balloon-borne demonstrators as testbeds for future space missions. Balloon experiments offer a unique opportunity to validate detector technologies in near-space conditions, bridging the gap between laboratory developments and full-scale space missions.
In this contribution, we will present results from the sensitivity calculation of a large-acceptance magnetic spectrometer, outlining its capability to measure rare cosmic-ray components, including antimatter. In particular, we will show that the acceptance calculation for 30-day-long balloon flights leads to exposures as large as hundreds of cm² sr years, making them highly relevant for comparison with long-duration space missions. Additionally, we will showcase simulation results exploring possible layouts for the magnetic spectrometer, aiming to optimize tracking resolution, momentum measurement, and overall instrument performance. These studies provide critical input for the design and feasibility assessment of future space-based experiments, such as Aladino or AMS-100.
This work underscores the importance of high-precision detection technologies in the roadmap toward next-generation antimatter searches. By leveraging balloon-borne demonstrators, we can refine instrumental designs and validate key performance parameters in realistic conditions, paving the way for future space missions dedicated to high-energy cosmic-ray physics.

Speaker: Roberto Iuppa (Universita degli Studi di Trento and INFN (IT))

16:20 The MoonRay concept of a high energy cosmic radiation telescope at the Moon

The MoonRay project is carrying out a concept study of a permanent lunar cosmic-ray (CR) and gamma-ray observatory, in view of the implementation of habitats on our satellite. The idea is to build a modular telescope that will be able to overcome the limitations, in available power and weight, of the present generation of CR instruments in Low Earth Orbit, while carrying out high energy gamma-ray observations from a vantage point at the South Pole of the Moon.
An array of fully independent modules (towers), with limited individual size and mass, can provide an acceptance one order of magnitude larger than instruments in flight or planned to be operative within the decade. The modular telescope is designed to be deployed progressively, during a series of lunar missions, while collecting meaningful scientific data at the intermediate stages of its implementation. The operational power will be made available by the facilities maintaining the lunar habitats.
With a geometric factor close to 15 m$^{2}$sr and about 8 times larger sensitive area than FERMI-LAT, MoonRay will be able to carry out a very rich observational program over a time span of a few decades with an energy reach of 10 PeV allowing the exploration of the CR “knee” and the observation of the Southern Sky with gamma rays well into the TeV scale.
Each tower is equipped with three instruments. A combined Charge and Time-of-Flight detector (CD-ToF) can identify individual cosmic elements, leveraging on an innovative two-layered array of pixelated Low Gain Avalanche Diode (LGAD) sensors, with sub-ns time resolution. The latter can achieve an unprecedented rejection power against back-scattered radiation from the calorimeter. It is followed by a tracker, providing also photon conversion, and by a thick crystal calorimeter (55 radiation lengths, 3 proton interaction lengths at normal incidence) with an energy resolution of 30-40% (2%) for protons (electrons) and a proton/electron rejection in excess of 10$^{5}$.
In this presentation, a time resolution close to 100 ps, obtained with prototypal arrays of 3mm x 3mm LGAD pixels, will be reported from a recent test campaign carried out at CERN with Pb beam fragments.

Speaker: Pier Simone Marrocchesi (University of Siena and INFN Pisa)

16:35 Cosmic Radiation Detector Based on Polymethyl Methacrylate

Cosmic rays are detected in two ways: by detecting photons or by detecting ions, which are produced when cosmic radiation interacts with a material medium, such as water or plastic. Cosmic radiation is composed of a variety of elementary particles and heavy nuclei, but especially muons, which are the most abundant, with an electrical charge, at sea level. To study this radiation, we have developed a detector based on a $10\:cm$ diameter and $60\:cm$ long polymethyl methacrylate bar, with two detection channels based on two photomultiplier tubes, which are used to sense the photons produced in the acrylic bar by the Cherenkov effect or scintillation when cosmic rays hit it. We present technical details of the planning, design, construction and characterization of this mini cosmic ray detector and some preliminary physical results.

Speaker: Salvador Aguilar (Laboratorio Internacional de Partículas Elementales, Departamento de Física, DCeI, CL. UGTO)

15:20 → 16:36 CRI: atmospheric leptons

15:20 12-Years Observation of Seasonal Variation of Atmospheric Neutrino Flux with IceCube

High-energy atmospheric muon neutrinos are detected by the IceCube Neutrino Observatory with a high rate of almost a hundred thousand events per year. Being mainly produced in meson decays in cosmic-ray-induced air showers in the upper atmosphere, the flux of these neutrinos is expected to depend on atmospheric conditions and thus features a seasonal variation. The magnitude of this effect can be described with a correlation coefficient ⍺, whose previous measurement with 6 years of IceCube data indicated a discrepancy to theoretical expectations. In this work, we present an update of the previous analysis, extending the statistics to 12-years of IceCube data, as well as adding the northern hemisphere to the analysis. We estimate the correlation coefficient in the southern hemisphere to be ⍺=0.325±0.022, which confirms the previous observation of the tension between the theoretical predictions and experimental measurements with significance >3σ. Furthermore, the seasonal variation in the northern hemisphere has also been observed for the first time, with ⍺=0.731±0.222. Investigations into systematic effects reveal that the observations not only show a weaker correlation compared to the predictions, but also deviate from the expected linear relation between the atmospheric neutrino flux and the atmospheric temperature.

Speaker: Shuyang Deng

15:35 Studying Time Variation in the TeV Cosmic Ray Anisotropy with IceCube Cosmic-Ray Muons

There is an observed anisotropy in the arrival direction distribution of cosmic rays in the TeV-PeV regime with variations on the scale of one part in a thousand. While the origin of this anisotropy is an open question, a possible factor is cosmic-ray interactions with interstellar and heliospheric magnetic fields. These magnetic fields may change over time - for example, due to changes in solar activity throughout its 11-year solar cycle. The cosmic-ray anisotropy can reflect these time-dependent magnetic fields. In addition to these speculative sources, there are several known sources of time variation in this anisotropy, such as the Compton-Getting Effect from the Earth’s orbital motion. We discuss a preliminary study with limited statistics of time variation undertaken by the IceCube Neutrino Observatory, including a measurement of the Compton-Getting Effect as well as a general, model-independent search for other time variations. Further, we use the Compton-Getting Effect to present a preliminary measurement of the cosmic-ray spectral index as a function of energy below the knee.

Speaker: Perri Zilberman

15:50 Unfolding the Atmospheric Muon Flux with IceCube: Investigating Stopping Muons and High-Energy Prompt Contributions

Atmospheric muons produced in cosmic-ray air showers are classified as conventional muons from pion and kaon decays and prompt muons from heavy hadron decays. Conventional muons dominate at lower energies, and the prompt component becomes more significant at PeV energies and above. Precisely measuring the atmospheric muon flux from a few GeV to several PeV is valuable for advancing our understanding of cosmic-ray interactions and testing hadronic interaction models. Low-energy muons that stop within the IceCube in-ice array provide valuable information about the energy spectrum of muons from a few 100 GeV up to 10 TeV.
Machine learning techniques are employed to enhance event reconstruction and selection to provide insights into the conventional and prompt components. This contribution presents the unfolding of the energy spectrum of stopping muons in IceCube as well as the unfolding of high-energy muons to probe the prompt component.

Speaker: Pascal Gutjahr (TU Dortmund University)

16:05 Unraveling the Unexpected Seasonal Variation of Multi-Muon Events at NO$\nu$A

The seasonal variation of single muons is a well-understood phenomenon, mainly driven by a positive correlation with atmospheric temperature fluctuations. However, the rate of multi-muon events measured by several experiments has revealed an opposite seasonal modulation in multi-muon events, which remains unexplained by any previous studies using CORSIKA simulations. For the first time, we quantitatively describe the phase and amplitudes of the seasonal variation for cosmic multi-muon events detected by the NO$\nu$A Near Detector. We can further explain the amplitude dependence for multi-muon events across various multiplicities. To address this, we use the general-purpose Monte Carlo code FLUKA-CERN 4.4.1, which provides a more realistic description of the detector, atmospheric profiles, and muon propagation underground. Finally, we compare our results with those obtained from the latest CORSIKA version 7.8000, utilizing the most up-to-date high-energy hadronic interaction models Sibyll 2.3e, QGSJETIII-01, and EPOS LHC-R. Our findings provide a fresh perspective on seasonal muon flux modulation and offer key constraints for cosmic-ray interaction models and underground detector studies.

Speaker: Jordi Tuneu (Institute of Physics of the Czech Academy of Science)

16:20 Seasonal Variation of the Underground Muon Flux in Daya Bay Using the Full Data Set

High-energy cosmic rays enter Earth's atmosphere where they interact with atmospheric particles to generate charged mesons that subsequently decay into muons. As the atmospheric temperature rises, the density decreases, increasing the mean free path of pions and kaons and thus their likelihood of decaying into cosmic ray muons. The positive correlation that results as a consequence of this effect has been observed in multiple experiments. The Daya Bay Reactor Neutrino experiment consists of three experimental halls, each with a different level of rock overburden, making it an ideal setup to also observe this behavior. In this study, we analyze the full Daya Bay dataset to extract correlation coefficients for each hall by examining the relationship between the muon rate and the effective atmospheric temperature. We investigate multiple analysis techniques and evaluate both their advantages and limitations. In this talk, we will present our latest results and compare them to the theoretical model prediction as well as to the published results of other experiments.

Speaker: Katherine Dugas (University of California, Irvine)

15:20 → 16:50 CRI: research & development

15:20 The Fluorescence Camera for the PBR mission

The Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) Balloon with Radio (PBR) is an instrument designed to be borne by a NASA suborbital Super Pressure Balloon (SPB), in a mission planned to last as long as 50 days. The PBR instrument consists of a 1.1 m aperture Schmidt telescope, similar to the POEMMA design, with two cameras in its hybrid focal surface: a Fluorescence Camera (FC) and a Cherenkov Camera (CC), both mounted on a frame that can be tilted to point from nadir up to 13 degrees above the horizon. The FC camera is designed to detect the fluorescence emission of Extensive Air Showers produced by Ultra-High Energy Cosmic Rays from sub-orbital altitudes. This measurement will validate the detection strategy for future space-based missions, such as POEMMA. The FC will be made of 4 Photo Detection Modules (PDMs), each consisting of a 6×6 matrix of 64-channel Multi Anode PhotoMulTipliers (MAPMT), for a grand total of 2304 pixels for each PDM. Custom-designed SPACIROC-3 ASICs perform single photoelectron counting on each pixel as well as charge integration on groups of 8 pixels to measure extremely bright or fast signals, reaching a double pulse resolution in the order of 10 ns for a 1 microsecond acquisition gate. A field flattener lens and a BG3 filter, to match the wavelength range of interest (300-400 nm), are mounted in front of the PDM. The camera will be able to detect showers in a field of view of 24x24 square degrees, with a pixel size on ground corresponding to 115 m. Details on the camera design and implementation will be given, along with the expected performance and the state of the construction.

Speaker: Francesco Cafagna (Universita e INFN, Bari (IT))

15:35 The Cherenkov Camera for the PBR mission

The POEMMA-Balloon with Radio (PBR) mission is a NASA super-pressure balloon experiment designed to advance the detection of ultra-high-energy cosmic rays, high-altitude horizontal air showers, and astrophysical neutrinos. A key instrument of PBR is the Cherenkov Camera (CC), which utilizes a 2048-pixel SiPM camera to detect the optical Cherenkov emission from cosmic-ray-induced air showers and search for upward-going signals indicative of neutrinos.
The CC operates in the 320–900 nm spectral range with a 10 ns integration time, leveraging a bi-focal optical design to enhance detection efficiency. The CC enables precise reconstruction of shower trajectories and provides valuable data on cosmic rays' composition and energy distribution. PBR’s sub-orbital altitude is particularly advantageous for these measurements, offering a unique vantage point that bridges the observational gap between ground-based and space-based instruments. Additionally, the CC will play a critical role in neutrino searches, detecting tau-lepton decay showers from Earth-skimming neutrinos associated with astrophysical transients. By integrating the CC with fluorescence and radio detection systems, PBR will pioneer a multi-messenger approach to high-energy cosmic phenomena, refining observational techniques for future space-based missions.
This contribution will describe the current status of the development of the CC as well as its expected performance.

Speaker: Valentina Scotti

15:50 The Global Cosmic Ray Observatory -- Challenging next-generation multi-messenger astronomy with interdisciplinary research

The origin of ultra-high-energy cosmic rays (UHECRs) is one of the most intriguing mysteries in the astroparticle physics and high-energy physics. Since UHECRs with light mass compositions are less deflected by the Galactic and extragalactic magnetic fields, their arrival directions are more strongly correlated with their origins. Charged-particle astronomy with UHECRs is hence a potentially viable probe of extremely energetic phenomena in the nearby universe. The Global Cosmic Ray Observatory (GCOS) is a proposed next-generation observatory to elucidate these origins using precise measurements of UHECRs with unprecedented exposure and mass identification capabilities. We will focus on the ideas and requirements for GCOS summarized in https://arxiv.org/abs/2502.05657 and share the latest results of detector developments and future perspectives with interdisciplinary research.

Speaker: Toshihiro Fujii (Osaka Metropolitan University)

16:05 Progress towards stereo observation of ultra-high-energy cosmic rays with Fluorescence detector Array of Single-pixel Telescopes

Ultra-high-energy cosmic rays (UHECRs) are the most energetic particles ever detected. Their production mechanisms remain unknown, but the conditions in which they are generated are likely to be extreme. Cosmic rays that achieve the highest energies are rare, and their flux at Earth is extremely low. As a result, next-generation experiments with large effective areas are required and under development.The Fluorescence detector Array of Single-pixel Telescopes (FAST) is one such project, that utilizes the atmospheric fluorescence detection technique. Although this limits observation time compared with ground particle detectors, it enables direct measurements of Xmax, a crucial parameter sensitive to the primary cosmic-ray composition. FAST will achieve large-area coverage by significantly reducing the cost of telescopes. This necessitates a simplified telescope compared to conventional designs. Demonstrating the feasibility of our telescope and observational method is essential.To validate the FAST concept, prototype telescopes have been deployed at the Pierre Auger Observatory and the Telescope Array experiment. In this talk/contribution, we report the latest analysis of energy spectra and $X_\mathrm{max}$ measurements using data collected since 2018, along with an assessment of potential systematic uncertainties. Additionally, we present the progress towards stereo observation using upgraded prototype telescopes.

Speaker: Shunsuke Sakurai (Osaka Metropolitan University)

16:20 The CRAFFT Project: Developing a Fully Automated Fluorescence Detector for UHECR observation

The origin of ultra-high-energy cosmic rays is still an open question, requiring next-generation observation technology. The CRAFFT project is developing a next-generation fluorescence detector designed for low-cost and fully automated observations with a simple structure. In this study, we report the successful detection of ultra-high-energy cosmic ray air showers using a prototype telescope and ongoing tests for full automation. This presentation provides an overview of the CRAFFT project, highlighting hardware development for autonomous observation, testing of the self-operating system, and network testing for data collection.

Speaker: Yuichiro Tameda (Osaka Electro-Communication University)

16:35 AugerPrime Surface Detector Electronics: requirements, verification and performance

The Pierre Auger Observatory has recently undergone a major upgrade, called AugerPrime, tailored to answer the current most burning questions in the Ultra-High-Energy cosmic ray detection. The AugerPrime upgrade consists of adding, on top of each station, a scintillator detector to separate the muonic and electromagnetic component of the shower for better primary identification, and a radio antenna to measure the emission of air showers in 30-80 MHz range. An additional small diameter photomultiplier in installed in each station to increase the dynamic range for signal detection. New electronic modules, that have been installed on all stations, provide a sufficient number of channels for readout of the additional detectors, as well as faster sampling, increased dynamic range and processing capability. Underground muon detector and radio detector signals are also aggregated by the new electronics. In this contribution we summarize the performance of the new electronics modules with respect to the requirements, describe the verification procedure and give the results in the laboratory tests compared to the performance in the field.

Speaker: Martina Bohacova

15:20 → 16:50 DM: direct detection

15:20 Quenching factor measurement for NEWS-G

The NEWS-G experiment, located at the Sudbury Neutrino Observatory (SNO) in Canada, is searching for Weakly Interacting Massive Particles (WIMPs) in the sub-GeV mass range. This direct dark matter detection experiment uses Spherical Proportional Counters (SPCs) as detectors, which measure nuclear recoils in noble gases. Since nuclear recoils are quenched compared to electronic recoils, precise measurements of the quenching factor (QF) are essential for accurately calibrating the detector for nuclear recoil events. Therefore, it plays a key role in determining sensitivity of the detector towards dark matter detection. To facilitate these in-beam QF measurements, we recently developed a neutron detector for detecting the scattered neutron from SPC.

This work outlines the ongoing efforts of the NEWS-G group to measure the quenching factor (QF) for various gas mixtures, pressures, and neutron energies. The development and preliminary results from our new neutron detector will also be discussed. Additionally, a brief overview of our recent measurements conducted with the tandem accelerator at the University of Montreal will be presented.

Speaker: Neha Panchal (Postdoctoral Fellow)

15:35 The SABRE South Experiment at the Stawell Underground Physics Laboratory

SABRE is an international collaboration that will operate similar particle detectors in the Northern (SABRE North) and Southern Hemispheres (SABRE South). This innovative approach distinguishes possible dark matter signals from seasonal backgrounds, a pioneering strategy only possible with a southern hemisphere experiment. SABRE South is located at the Stawell Underground Physics Laboratory (SUPL), in regional Victoria, Australia.
SUPL is a newly built facility located 1024 m underground (∼2900 m water equivalent) within the Stawell Gold Mine and its construction has been completed in 2023.
SABRE South employs ultra-high purity NaI(Tl) crystals immersed in a Linear Alkyl Benzene (LAB) based liquid scintillator veto, enveloped by passive steel and polyethylene shielding alongside a plastic scintillator muon veto. Significant progress has been made in the procurement, testing, and preparation of equipment for installation of SABRE South. The SABRE South muon detector and the data acquisition systems are actively collecting data at SUPL and the SABRE South’s commissioning is planned to be completed by the end of 2025.
This presentation will provide an update on the overall progress of the SABRE South construction, its anticipated performance, and its potential physics reach.

Speaker: Dr Irene Bolognino (The University of Adelaide)

15:50 The DarkSide-20k Dark Matter Detector: Physics Goals and Data Acquisition

In this talk I will introduce the DarkSide-20k detector, now under construction in the Gran Sasso National Laboratory (LNGS) in Italy, the largest underground physics facility in the world devoted to astroparticle physics. The experimet is designed to directly detect dark matter by observing weakly interacting massive particles (WIMPs) scattering off the nuclei in 20 tonnes of underground-sourced liquid argon in the dual phase time projection chamber (TPC).

The nature of dark matter remains unknown and its origin is currently one of the most important questions in physics. Direct searches for WIMP dark matter particle interactions with ordinary matter are carried out with large detectors located in underground laboratories to suppress the background of cosmic rays.

The light generated during the interactions in the liquid argon is detected by custom silicon photomultipliers (SiPMs) assemblies of size 20 cm by 20 cm. These photodetectors have linear signal response up to 100 photons and signal to noise ratio of 5 for a single photon. The units installed in the veto detectors are equipped with application specific integrated circuits (ASICs) coupled to SiPM, while those for the TPC employ a discrete element front-end with similar performances.

The data acquisition system (DAQ) for the DarkSide-20k experiment is designed to acquire signals from the 2720 channels of these photosensors in a triggerless mode. The data rate from the TPC alone is expected to be at the level of 2.5 GB/s and will be acquired by 36 newly available commercial VX2745 CAEN 16 bit, 125 MS/s, high channel density (64 ch.) waveform digitizers. The Veto detector is readout by an additional 12 modules. The data is first transferred to 24 Frontend Processor machines for filtering and reduction. Finally the data stream is received by another set of Time Slice Processor computers where the whole detector data is assembled in fixed length time series, analyzed and stored for offline use. These operations will be supervised by a Maximum Integration Data Acquisition System (MIDAS) developed in the Paul Scherrer Institute in Switzerland and TRIUMF laboratory in Canada.

Speaker: Marek Bohdan Walczak (Gran Sasso Science Institute (IT))

16:05 SuperCDMS Experiment at SNOLAB: Current Status and Recent CUTE Results

The Super Cryogenic Dark Matter Search (SuperCDMS) experiment at SNOLAB explores dark matter particles in the widely unexplored mass range of 1-10 $GeV/c^2$. The experiment will deploy a total of 24 detectors with silicon and germanium target substrates 2 km deep underground in SNOLAB. The detectors are arranged in four towers, combining the low-threshold sensitivity of high-voltage (HV) phonon detectors with the excellent background discrimination of phonon-charge (iZIP) detectors. The combination will give SuperCDMS a world-leading edge in exploring the low-mass, low-cross-section dark matter candidates.
Over the past year, SuperCDMS completed testing a single HV tower at the Cryogenic Underground TEst facility (CUTE). The CUTE run, which concluded in February 2024, demonstrated the ability to conduct in-situ operations including characterization, calibration, and exploration of Neganov-Trofimov-Luke (NTL) phonon amplification. This presentation will highlight key results from CUTE, along with the current status and prospects of the first SuperCDMS science run.

Speaker: Moaaz Elwan

16:20 IceCube as a direct detector of sub-GeV dark matter

The study of non-gravitational effects of Dark Matter (DM) is a growing field of research, leading to the development of numerous dedicated experiments. Astrophysical and cosmological observations show that the galactic component of DM is non-relativistic; this results in a rapid loss of sensitivity to sub-GeV DM masses in Direct Detection experiments with nuclear targets sensitive to keV-scale recoil energies.

Relying only on the assumption that DM scatters on a Standard Model (SM) target particle, a higher-speed component of the flux arises, originating from the upscattering of the galactic DM on Cosmic Rays, which peaks in the GeV energy range.
Neutrino telescopes like Super-Kamiokande are sensitive to these energies and have been already used as DM detectors, setting world-leading limits. Higher energy telescopes, such as IceCube, are also sensitive to these energies and could be even more promising, given their larger volumes. How to best use them to detect sub-GeV DM?

In this contribution I will address this question, for both spin-independent and spin-dependent DM-SM interactions, and establish sensitivities to the scatterings of sub-GeV DM with nuclei in IceCube.

Speaker: Allegra Cavicchi (University of Bologna)

16:35 Halo-independent bounds on the WIMP-nucleon couplings of long-range interactions from direct detection and neutrino observations

I discuss the bounds on WIMP-proton and WIMP-neutron couplings of spin-independent and spin-dependent long-range interactions via massless mediator. I update the bounds in the Standard Halo Model for direct detection and the neutrino signal from WIMP annihilation in the Sun, and set halo-independent bounds using the single-stream method.

In the case of a massless mediator the capture rate in the Sun diverges and is regularized by removing the contribution of WIMPs locked into orbits that extend beyond the Sun-Jupiter distance. I discuss the dependence of the SHM bounds on the Jupiter cut showing that it can be sizable for a WIMP-proton coupling of a spin-dependent long-range interaction and a WIMP mass exceeding 1 TeV.

I show that the halo-independent analysis shows that mostly the relaxation of the bounds compared to the SHM is of the same order of that for contact interactions, relatively moderate in the low and high WIMP mass regimes and large for intermediate WIMP mass range. However, in the case of a WIMP-proton coupling of a spin-dependent long-range interaction, the relaxation of the bounds becomes not reliable at large WIMP mass range due to the sensitivity of the SHM capture rate in the Sun to low incoming WIMP speeds. In contrast, the halo–independent bounds are robust against the details of the velocity distribution including the Jupiter cut and the local escape speed.

Speaker: Dr Sunghyun Kang (Center of Quantum SpaceTime(CQUeST), Sogang University)

15:20 → 16:50 GA: star clusters & miscellaneous

15:20 Discovery of an outflow driven by the massive star cluster Westerlund 1

Outflows from star-forming regions are thought to have a profound effect on galaxy evolution. The role of cosmic rays in such outflows is however not clear at present. We report on the discovery of a cosmic-ray loaded outflow from the young massive star cluster Westerlund 1, which is known to accelerate cosmic rays to several tens of TeV. The outflow manifests itself as a ~150 pc-diameter GeV gamma-ray source in the direction of a low-density region in the interstellar medium at the edge of the Galactic disc. The GeV source is offset from the TeV gamma-ray emission surrounding the cluster, indicative of relativistic electrons that have escaped the cluster environment. Our results suggest the presence of cosmic-ray nuclei in the outflow, with a density far exceeding that in the average interstellar medium. We discuss possible implications of our work.

Speaker: Lars Mohrmann (Max Planck Institute for Nuclear Physics, Heidelberg)

15:35 Observability of young star clusters in gamma rays: the role of Wolf-Rayet stellar winds

Stellar wind termination shocks are considered potential sites for efficient particle acceleration, allowing an explanation for the overabundance of Ne²² observed in cosmic rays (CRs) through Wolf-Rayet stars (WRs) and providing a minor but necessary contribution to the observed flux of Galactic CRs. However, only a few powerful star clusters such as Westerlund 1 and Cygnus OB2 have been firmly detected in high energy gamma rays (TeV-PeV), as well as very young star clusters embedded in parent dense molecular cloud at lower energies (around GeV). This lack of detection is limiting our ability to test the different scenarios of cosmic-ray acceleration in stellar clusters. Therefore, identifying the most promising clusters in terms of observability (so the most powerful and nearest ones) is now crucial to refine our understanding of particle acceleration and transport in these environments.

Recent attempts to catalog star clusters have leveraged Gaia data to identify individual stars across the Galaxy. By summing the kinetic power of detected stars and extrapolating from initial mass functions (IMFs), total cluster luminosities can be estimated. However, this approach has two key limitations. First, it relies on extensive modeling to infer the full stellar population and to pass from bolometric to kinetic luminosity. Second, it is hindered by Gaia’s limitations in measuring the magnitudes of the most luminous stars, leading to incomplete or inaccurate luminosity estimates for massive clusters.

We propose a more direct and robust method to identify the most powerful stellar clusters: focusing exclusively on detected Wolf-Rayet stars. These stars dominate the kinetic power output of clusters, with a single WR star sometimes matching or exceeding the luminosity of an entire OB star cluster. By summing the contributions of WR stars within each cluster, we obtain a reliable and nearly complete sample of the most powerful YMSCs, without the need for IMF extrapolations. This approach provides a targeted list of the most promising clusters in terms of observability and typically offers a solid foundation for investigating their role in cosmic-ray acceleration up to PeV energies. We also explore potential coincidences between these WRs or clusters and gamma-ray sources detected by HESS, LHAASO, or Fermi-LAT, to assess possible associations.

Speaker: Alexandre INVENTAR (APC Laboratory)

15:50 The population of Galactic young massive star clusters in the TeV range

Young massive star clusters (YMSCs) can produce gamma rays in the very-high-energy (VHE, E>100 GeV) range and have been proposed as sources that can accelerate cosmic rays up to PeV energies. Observations with current instruments have lead to the detection of only a few YMSCs but future instruments should significantly increase this number. However, the details of the production of the VHE emission are not well understood: What is the spectrum of accelerated particles? What is the efficiency of cosmic-ray production? What fraction of the wind luminosity is converted into the turbulent magnetic field?

To address these questions, we simulate the population of YMSCs in the gamma-ray domain, by means of Monte Carlo methods, and apply the constraints based on the subsample of YMSCs currently detected at TeV energies. We confront our simulated populations with the catalogue of the H.E.S.S. Galactic Plane Survey, the third HAWC catalogue, and the first LHAASO catalogue, allowing us to investigate crucial aspects of particle acceleration at YMSCs.

Speaker: Rowan Batzofin (University of Potsdam)

16:05 Non-thermal emission from local young massive stellar clusters and detection prospects with current and next generation instruments

Cosmic-ray acceleration up to PeV energies has been suggested to take place in massive and young stellar clusters. The formation of a strong termination shock driven by the collective action of stellar winds in compact clusters offers a promising location where efficient particle acceleration might take place over Million year timescales. Moreover, the impulsive acceleration from supernova remnants (SNRs) occurring in their cores provides a further source of power, soon becoming dominant one. The subsequent hadro-nuclear interactions of these particles result into gamma-ray and neutrino production. Within a scenario of particle acceleration at the cluster wind termination shock and at SNRs, we compute the emerging gamma-ray and neutrino signal from star clusters within the Milky Way. We further evaluate detection prospects of the gamma-ray and neutrino fluxes with the Cherenkov Telescope Array (CTA), the Large High Altitude Air Shower Observatory (LHAASO), and KM3NeT, by adopting detailed differential sensitivity curves calculated for extended sources.

Speaker: Dr Silvia Celli (La Sapienza Università di Roma and INFN)

16:20 Gamma-ray emission from the young massive star cluster NGC 6611 in the Eagle nebula

Massive Star Clusters (SCs) have been proposed as important CR sources, with the potential of explaining the high-energy end of the Galactic cosmic-ray (CR) spectrum, that Supernova Remnants (SNRs) seem unable to account for. Thanks to fast mass losses due to the collective stellar winds, the environment around SCs is potentially suitable for particle acceleration up to PeV energies and the energetics is enough to account for a large fraction of the Galactic CRs, if the system is efficient enough. A handful of star clusters have been detected in gamma-rays confirming the idea that particle acceleration is taking place in this environment, but clear constraints on the acceleration efficiency are often lacking.

Here we present the new analysis of Fermi-LAT data collected from the region of M16 (known as the Eagle Nebula), a HII region hosting the young massive star cluster NGC 6611. The young age (~1 Myr) of the cluster guarantees that no SN has exploded in the region, allowing us to constraints the acceleration efficiency contributed by the winds of NGC 6611. The clear correlation with a dense gas clouds helps in the interpretation and modeling of the emission as due to hadronic interactions.

Speaker: Giada Peron (Inaf Osservatorio Astrofisico di Arcetri)

16:35 Self-modulation of cosmic rays penetrating dense molecular clouds: Impact on gamma-ray emission

Recent Fermi LAT observations of nearby giant molecular clouds show deficits in the gamma-ray residual map when the expected diffuse emission is modelled assuming uniformly distributed cosmic rays (CRs) [1]. The authors pointed out that the observed emission “holes” reflect the lack of penetration of <∼10 GeV CRs into denser regions, and proposed that the CR deficit is caused by slower CR diffusion in the clouds.

Several years ago, we developed a theory of CR self-modulation in dense molecular clouds [2]. We showed that the modulation occurs due to CR scattering on self-generated turbulence, excited by the CRs in the diffuse envelope. In a subsequent paper [3] we applied the theory to investigate whether the mechanism of self-modulation can explain gamma-ray features observed in the Galactic center. Assuming a simplified cloud model, with a dense core and a diffuse surrounding envelope of a constant gas density about 10 cm−3, we showed that emission is noticeably suppressed at GeV energies for the cloud column densities over 10^23 cm−2. However, the recently developed 3D dust extinction maps [4] indicate that the gas distribution in envelopes is highly inhomogeneous, decreasing monotonically from the center, and typical density values are substantially lower than that assumed in [3].

We have now generalized the theory of CR self-modulation for inhomogeneous envelopes, making it applicable to arbitrary monotonically decreasing density profiles [5]. In this case, we found that noticeable suppression of GeV gamma-rays already occurs when the gas column density exceeds a few times 10^22 cm−2. For the conditions of giant clouds [1], we obtained excellent quantitative agreement with the observed emission holes. We will present details of the developed theory, discuss comparison with the observations, and point out implications for the CR ionization in molecular clouds.

[1] Yang, R.-z., Li, G.-X., Wilhelmi, E. d. O., et al. 2023, Nature Astronomy, 7, 351
[2] Ivlev, A. V., Dogiel, V. A., Chernyshov, D. O., et al. 2018, ApJ, 855, 23
[3] Dogiel, V. A., Chernyshov, D. O., Ivlev, A. V., et al. 2018, ApJ, 868, 114
[4] Edenhofer, G., Zucker, C., Frank, P., et al. 2024, A&A, 685, A82
[5] Chernyshov, D. O., Ivlev, A. V., Kiselev A. M. 2024, PRD, 110, 043012

Speaker: Alexei Ivlev

15:20 → 16:50 NU: highlights & analysis

15:20 Hyper-Kamiokande: Neutrino astrophysics and Status.

Hyper-Kamiokande (Hyper-K) is a multi-purpose next-generation neutrino experiment aiming to start its operation in 2027.
The Hyper-K water Cherenkov detector consists of a two-layered cylindrical ultra-pure water tank with a height (diameter) of 64 (71) meters. The inner detector will be equipped with twenty thousand twenty-inch photomultipliers and 800 multi-PMT modules. These sensors detect the time and charge of the water Cherenkov radiation to reconstruct the properties of charged particles induced by neutrino interaction.

The Hyper-K detector provides a fiducial volume of 188 kilotons, 8.4 times that of preceding experiment Super-Kamiokande. Hyper-K's rich physics program includes accelerator neutrinos, atmospheric neutrinos, proton decay, and neutrino astrophysics, which are studied through the study of solar, supernova burst, and supernova relic neutrinos. With its comprehensive research programs, Hyper-K will be pivotal in advancing the frontier of neutrino physics.
This presentation will discuss the current project status and physics potential of Hyper-K in neutrino astrophysics.

Speaker: Takatomi Yano (ICRR, University of Tokyo)

15:35 Measurement of TeV-scale muon neutrino cross sections using Super-Kamiokande

We present a measurement of the muon neutrino charged-current (CC) cross section using atmospheric neutrinos observed in Super-Kamiokande (SK). This analysis focuses on upward-going muons produced by muon neutrinos interacting in the rock beneath the detector, providing a clean sample with minimal cosmic muon contamination. The primary energy range extends to 5 TeV, covering a blind spot between accelerator-based measurements and neutrino telescopes. The measured muon neutrino CC cross section is consistent with theoretical predictions and previous results, offering important constraints on neutrino interaction models and reducing uncertainties for future high-energy neutrino studies.

Speaker: Nahid Bhuiyan (STFC)

15:50 Construction and Commissioning of the JUNO detector

The Jiangmen Underground Neutrino Observatory (JUNO) is a state-of-the-art neutrino physics experiment located in South China. With 20 ktons of ultra-pure Liquid Scintillator (LS), JUNO aims to achieve groundbreaking measurements, including the determination of Neutrino Mass Ordering (NMO) and the precise measurement of three neutrino oscillation parameters with sub-percent precision. The JUNO detector consists of a Central Detector (CD), a water Cherenkov detector, and a top tracker detector. The CD is equipped with 17,612 20-inch PhotoMultiplier Tubes (PMTs) and 25,600 3-inch PMTs, delivering an energy resolution better than 3% at 1 MeV. Four independent calibration systems are employed to ensure an absolute energy scale uncertainty of less than 1% across the reactor antineutrino energy range. Beyond reactor neutrinos, JUNO has a broad physics program, including studies of solar neutrinos, supernova neutrinos, geoneutrinos, atmospheric neutrinos, and searches for physics beyond the Standard Model, such as nucleon decay. The detector installation was completed in December 2024, and the LS filling and system commissioning are currently underway. In this talk, I will present the detector design, construction milestones, and the commissioning performance of JUNO's subsystems.

Speaker: Cong Guo (Institute of High Energy Physics, Chinese Academy of Science)

16:05 The ANTARES detector: two decades of neutrino searches in the Mediterranean Sea

The ANTARES detector was the first neutrino telescope in seawater, operating successfully from 2006 to 2022 in the Mediterranean Sea. All challenges related to the operation in the deep sea were accurately addressed by the collaboration. Deployment and connection operations have become smoother over time; data taking and constant re-calibration of the detector due to the variable environmental conditions was fully automated.
A wealth of results on the subject of astroparticle physics, particle physics and multimessenger astronomy have been obtained, despite the relative modest size of detector, paving the way to a new generation of larger detectors under the sea.
More than 100 journal papers have been published and this talk summarizes the efforts by the ANTARES collaboration that made the possibility to operate neutrino telescopes in seawater a reality and the results obtained in this endeavor.

Speaker: maurizio spurio (University of Bologna and INFN)

16:20 All-sky search for neutrino flares in the ANTARES legacy data

The ANTARES neutrino telescope operated from 2007 to early 2022 at the bottom of the Mediterranean Sea, with the primary goal of detecting neutrinos from astrophysical sources. Among these, variable and transient sources are particularly promising, as the timing of neutrino arrivals provides an additional distinguishing feature between signal and background, complementing energy and spatial information. The shorter the neutrino flares, the greater the enhancement in discovery potential compared to steady emissions. As part of the legacy analysis of ANTARES data, a time-dependent algorithm has been developed to search for event clustering in both space and time. For the first time, this method has been applied across a fine grid covering the entire ANTARES visible sky. The results of this analysis applied to the full ANTARES data sample are presented here.

Speaker: Agustín Sánchez Losa (IFIC)

16:35 Galactic Template Analysis with ANTARES

The observation of Galactic neutrinos, confirmed by IceCube in 2023, marks a major milestone in astroparticle physics. Underwater detectors like ANTARES, with superior angular resolution compared to IceCube DNN in their published results, provide a unique opportunity to refine our understanding of hadronic processes occurring in the Milky Way. By testing and fitting different phenomenological predictions of diffuse Galactic flux against neutrino data, we aim to constrain the mechanisms governing cosmic-ray progenitors, their transport, and their interactions with interstellar matter and radiation fields.
For nearly three years, the ANTARES and KM3NeT collaboration has developed a dedicated template likelihood framework capable of finely convolving phenomenological templates with the detector response function. Unlike conventional methods, this approach maintains the full spatial and energetic dependence of both the Galactic models and the detector response, avoiding information loss through marginalization of the parameter space, and enabling a more precise comparison between theory and observation.
This framework has been applied to the full ANTARES dataset, covering 15 years of live-time and incorporating both track-like and shower-like event topologies. In this contribution the constraints obtained using six different phenomenological models will be presented with a focus on the characterization of the diffuse Galactic neutrino flux by ANTARES. Comparisons with results from IceCube and the predictions for KM3NeT will be briefly discussed to highlight the complementarity of the ice and sea experiments in probing the Galactic neutrino sky.

Speaker: Mr Théophile Cartraud (APC)

15:20 → 16:50 SH: heliosphere

15:20 A 3D Monte Carlo calculation of the inverse Compton emission from the Sun and stars in presence of magnetic and electric fields

The solar steady emission in gamma rays is due to the interactions of Galactic Cosmic Rays with the solar atmosphere and with the low-energy solar photon field via inverse Compton scattering. The emission is sensitive to the magnetic field nearby the Sun and to the cosmic-ray transport in the magnetic field in the inner solar system. Modeling the inverse Compton emission in the presence of a magnetic field is therefore crucial to better interpret the observations. In a previous work we have presented a comprehensive calculation of the secondary productions due to the collision of cosmic rays with the solar atmosphere in presence of magnetic fields. In this contribution, we present a general approach to calculate the (anisotropic) inverse Compton scattering in a 3D Monte Carlo simulation, also in presence of magnetic and electric fields. After a short review of the scattering process of photons with electrons, examples of inverse Compton emission are presented, including the predictions for the Sun.

Speaker: Nicola Mazziotta (Universita e INFN, Bari (IT))

15:35 The numerical simulation of the Interplanetary Radiation Environment induced by Galactic Cosmic Rays

Galactic cosmic rays (GCRs) are high-energy charged particles originating from the Milky Way and widely distributed throughout the heliosphere. The space radiation environment induced by GCRs significantly impacts spacecraft operations. Numerical modeling provides a cost-effective approach to simulate space radiation environments, thus serves as a critical tool for predicting and evaluating particle radiation conditions. We developed a numerical model by solving cosmic ray transport equations using stochastic differential equations, and determined globally optimal model parameters through Markov Chain Monte Carlo (MCMC) methods. This model successfully reproduces proton and helium energy spectra observed by the PAMELA satellite and AMS-02 experiments during 2006-2017, establishing a database of cosmic ray drift and diffusion parameters under varying solar activity conditions. By comparing modulation parameters between protons and helium nuclei, we verified the consistency of solar modulation model parameters across different nuclear species.

Based on the modulation parameters, we employed an alternating direction implicit (ADI) scheme to solve cosmic ray transport equations, simulating energy spectra for cosmic ray nuclei with charge numbers ranging from 1 (hydrogen) to 26 (iron) throughout the heliosphere from 2006 to 2019. Utilizing these simulation results and incorporating flux-to-dose conversion coefficients published by the International Commission on Radiological Protection (ICRP), we assessed radiation doses induced by galactic cosmic rays during this period. Our calculations reveal spatiotemporal variations in human radiation exposure across the heliosphere.

Speaker: Xi Luo (Shandong Institute of Advanced Technology)

15:50 New constraints in modelling galactic deuterons in the heliosphere

The interest in the origin and modulation of cosmic ray deuterons is expected to increase significantly now that observations from AMS-02 and PAMELA detectors have become available. Observations made by AMS-02 reveal the spectral shape and features of galactic deuteron over the rigidity range 1.92 GV – 19.5 GV, whereas that from PAMELA are at a lower rigidity, from 0.75 GV – 2.5 GV. These observations provide interesting surprises with subsequent challenges to the established paradigm of the secondary origin of galactic deuterons. In this study a comprehensive 3D numerical model and a set of diffusion and drift coefficients, previously applied to a number of cosmic ray nuclei, together with a newly estimated local interstellar spectrum for deuterons, are used to simulate the modulation of deuteron from 2006 to 2022. The modelling results will be compared to observations made by PAMELA and AMS-02 detectors.

Speaker: Innocentia Itumeleng Ramokgaba (1. Centre for Space Research, North-West University, Potchefstroom, South Africa. 2. School of Physical & Chemical Sciences, North-West University, Mmabatho, South Africa)

16:05 Negative and positive electric charge flows through the solar system based on the Voyager data

Any stars permanently loose small amounts of mass during their lifetimes. This mass is propelled outward at velocities in the range 100 to 3000 km/s at ionization temperatures forming a continuous flow called stellar wind. As cosmic rays permanently and ubiquitously pervade the Galaxy, while impacting on stellar winds, loose energy.
This is empirically known since 70 years. Due to the prevailing positive electric charge of cosmic rays, the ambient around the star occupied by stellar winds remains positively charged until the charge excess dissipates through the local electric conductivity.
This work calculates for the first time the global electric charge deposited by cosmic rays in the solar system using cosmic-ray energy spectra measured by the Voyager mission. The charge balance of the cosmic-ray deposition and the concomitant neutralization process is analyzed.
The new and surprising result is that the total electric charge stored in the solar system is not null, implying permanent ambient electric fields, and a magnetic field of dipolar shape of 20-100 ?G from the deposited charge fraction rotating with the Sun.

Speaker: Prof. Antonio Codino (University of Perugia and INFN, Italy)

16:20 Stochastic Simulation of Galactic Cosmic-Rays in the Trapped Region beyond Heliopause

It was proposed previously that Galactic Cosmic-Rays(GCRs) are trapped in a region where the weak local interstellar magnetic field lines are spreaded apart by the heliopause in the northern hemisphere. Such a trapped region acts like a magnetic mirror for GCR particles. Once entering the trapped region from the outside interstellar space, GCR particles will encounter more complicated situation, besides the bouncing between the mirror points, they will move along the trajectories being perpendicular to the background magnetic field lines due to curvature/gradient drifts. As a result, some GCR particles will be trapped in the region, the nearly non-scattering movement along the magnetic field lines become slow, leading a total decrease of parallel diffusion. In this study, we will carry out the relevant stochastic simulation of GCRs based on the assumption that GCR particles do not move freely along the parallel direction of interstellar magnetic field. Some discussions about the work will be made base on our simulation results.

Speaker: XiaoCheng Guo

16:35 Local Time Variation of Interplanetary Scintillations

As measured by neutron monitors the flux of galactic cosmic rays exhibits non-statistical fluctuations at all observed timescales. Many of these fluctuations can be identified with specific structures in the solar wind. There is also a rather steady diurnal variation due to cosmic ray streaming in the overall pattern of solar modulation. There is also a spectrum of fluctuations usually termed “interpl anetary scintillations” attributed to the interaction of the cosmic rays with the general magnetic turbulence in the solar wind. In recent work considering correlations between pairs of neutron monitors we found a strong correlation associated with the diurnal variation. The phase of this variation was related to the difference in asymptotic longitude of the monitors, as one might expect. However, there was a clear peak in the cross-correlations that was instead ordered by the local time difference. In the present paper we examine clear local time variations of the autocorrelations and power spectra of individual stations in an attempt to isolate the effect of the diurnal streaming anisotropy from inherent variations in the power spectrum of the fluctuations.

Speaker: Prof. Paul Evenson (University of Delaware)

16:50 → 17:00 Break

16:50 → 18:30 NASA Physics of the Cosmos

Convener: Francesca Civano

16:50 Physics of the Cosmos Program: Space-based Cosmic-ray, Neutrino, and Gamma-ray Science in the 2030s

The Physics of the Cosmos (PhysCOS) Program is one of three focused programs contained within NASA's Astrophysics Division (APD). PhysCOS lies at the intersection of physics and astronomy and has the goal of exploring some of the most fundamental questions regarding the physical forces and laws of the universe. The PhysCOS Program Analysis Group (PhysPAG) serves as a community-based, interdisciplinary forum for soliciting and coordinating community analysis and input in support of PhysCOS objectives. It provides findings of analyses to the NASA Astrophysics Division Director.

The proposed session is focused on big science questions driving PhysPAG’s Cosmic Ray and Neutrino (CRN) and Gamma Ray (GR) Science Interest Groups (SIGs). In particular, the session will focus on understanding the current status of spaced-based studies for both cosmic rays and gamma rays as well as the questions that these communities aim to address in the future, looking towards the Astro 2030 Decadal Survey.

The session will include two talks, from representatives of the CRN and GR SIGs, a discussion panel with community members and a NASA representative, and open Q&A time. (edited)

Speakers: The two speakers will be S. Wissel/T.Aramaki and M. Crnogorcevic.

Panel: T.Aramaki (if he is not giving main talk), NASA HQ rep, S. Weakely (need to be invited), CRN person 1, Gamma-ray person 1, Gamma-ray person 2 (edited)

Speaker: Francesca Civano

17:10 Physics of the Cosmos Program: Envisioning the Future of Gamma-Ray Astronomy in Space

Space-based gamma-ray astronomy is a crucial tool for investigating extreme astrophysical phenomena and has played a key role in advancing our understanding of high-energy processes in the Universe. Gamma rays are deeply connected to gravitational waves, neutrinos, and cosmic rays, making them essential for multi-messenger astrophysics. As several current missions approach the end of their operational lifetimes, it is increasingly important to reassess the field’s scientific priorities and technical needs. The Future Innovations in Gamma-ray Science Analysis Group (FIG SAG) was formed to identify the key science drivers, required capabilities, and strategic priorities for gamma-ray astrophysics in the coming decades. In this presentation, I will provide an update on the group's progress and discuss opportunities for community engagement as we prepare a report for NASA Headquarters in 2025.

Speaker: Milena Crnogorcevic

17:30 Physics of the Cosmos Program: Cosmic Ray and Neutrino Science Interest Group

NASA’s Physics of the Cosmos Cosmic Ray and Neutrino Science Interest Group (CRNSIG) provides a forum for researchers across the broad energy spectrum of cosmic ray and neutrino observations to both discuss and provide NASA information about the science objectives and needs of the community, both now and planning for the future. In this talk, I will give a brief overview of PhysPAG’s CRNSIG, the portfolio of space-based instrumentation supported by NASA, and discuss open questions that space-based facilities can address in the next decade.

Speaker: Prof. Stephanie Wissel

17:50 Community discussion

17:00 → 18:30 PO-1

Friday 18 July

08:30 → 09:00 Registration

09:00 → 10:30 Plenary session

09:00 LHC physics for cosmic rays

High energy hadron-hadron collisions can provide many valuable inputs for cosmic ray physics. Forward hadron production measurements at the CERN Large Hadron Collider (LHC) probe equivalent fixed target collision energies of above a PeV, which are a crucial input for modelling of ultra high energy cosmic ray air showers. Recently the new LHC experiments, FASER and SND@LHC, have carried out the first studies with TeV neutrinos produced in the forward region of the LHC collisions, introducing a new tool to probe forward light- and heavy-hadron production. The 2025 LHC programme includes, for the first time, O-O and p-O collisions which will provide improved input for cosmic ray shower models, particularly with measurements from the dedicated LHCf experiment. In addition, an updated measurement of multi-muon cosmic ray events observed in the ALICE detector was recently released. This talk will summarise recent physics results and future prospects relevant for cosmic ray measurements from the suite of experiments at the LHC.

Speaker: Jamie Boyd (CERN)

09:45 Probing the origin of cosmic rays with LHAASO

The origin, acceleration, and propagation of Galactic cosmic rays is a fundamental question in astrophysics. The Large High Altitude Air Shower Observatory (LHAASO) is a major national science and technology infrastructure facility in China. With hybrid detection techniques of surface air shower array, underground muon detector array, water Cherenkov detector, and atmospheric Cherenkov telescope array, LHAASO has achieved unprecedent sensitivity and precision in surveying the ultra-high-energy gamma-ray sky and measuring the spectra and anisotropies of individual compositions of cosmic rays. Starting its full operation since 2021, LHAASO has made important progresses in observing Galactic PeVatrons and diffuse emission, measuring cosmic ray spectra and mass composition, as well as probing new physics. This talk will summarize the scientific results of LHAASO, and the role in understanding the origin of Galactic cosmic rays.

Speaker: Qiang Yuan

10:30 → 11:00 Coffee

11:00 → 12:00 Plenary session

11:00 Star clusters in the gamma-ray sky

Massive Star Clusters (SCs) have been proposed as additional contributors to Galactic Cosmic rays (CRs), to overcome the limitations of supernova remnants (SNRs) to reach the highest energy end of the CR spectrum. Thanks to fast mass losses due to the collective stellar winds, the environment around SCs is potentially suitable for particle acceleration up to PeV energies, and their energetics is enough to account for a large fraction of the Galactic CRs. Anyhow, the theoretical models need to be corroborated by clear observations. Despite the increasing number of detections at different energies, the contamination of other sources often makes it difficult to constrain the contribution arising from stellar winds only, unless one selects objects younger than a few Myr, namely before stars start to explode inside clusters.
I will review the results obtained with Fermi-LAT data towards a few massive young star clusters and discuss what implications these result have, especially concerning their contribution to the bulk of Galactic CRs.

Speaker: Giada Peron (Inaf Osservatorio Astrofisico di Arcetri)

11:30 Exploring the Ultra-High-Energy Universe: Highlights from the Pierre Auger Observatory

The Pierre Auger Observatory is the world’s largest facility dedicated to studying ultra-high-energy cosmic rays (UHECR). Located in Argentina, it spans 3,000 square kilometers and utilizes a hybrid detection system comprising over 1,600 water Cherenkov detectors and fluorescence telescopes. Since its inception in 2004, the Observatory has provided groundbreaking insights into the energy spectrum, mass composition, and arrival direction anisotropies of cosmic rays.
Phase I data analysis (with data from 2004 - 2022) has revealed critical features such as large-scale anisotropies, spectral features such as the instep and the suppression of flux at the highest energies, thus advancing our understanding of the origin and propagation of UHECR. The hybrid detection approach has enabled precise measurements of air showers and muon content, offering constraints on hadronic interaction models. Furthermore, searches for neutral particles have been performed, contributing to multi-messenger astrophysics.
The ongoing AugerPrime upgrade aims to refine mass composition studies by integrating scintillator detectors, improved electronics, underground muon detectors and radio antennas, enhancing sensitivity to primary cosmic-ray properties. This presentation will highlight key scientific achievements from Phase I and discuss the transformative potential of AugerPrime in addressing fundamental questions about the origin of UHECRs.

Speaker: Markus Roth (KIT)

12:00 → 13:20 DEI lunch session

12:00 → 13:20 Lunch

13:20 → 14:50 CRD: acceleration

13:20 Kinetic simulations of particle acceleration at shock waves in plasma with pre-existing turbulence

Astrophysical shocks are known to accelerate charged particles to relativistic energies, making them plausible sites for cosmic ray production. Numerical simulations are widely used to study shock acceleration, particularly due to its nonlinear nature. However, they do not always reproduce efficient particle energization. These simulations typically assume a homogeneous upstream medium, and our study aims to reveal whether pre-existing turbulence may have an effect. Using a novel simulation framework, we perform fully kinetic simulations of shocks propagating in turbulent media. Our results show that at nonrelativistic high-Mach-number oblique shocks, which model conditions in supernova remnants, electron acceleration is more efficient in the presence of pre-existing compressible turbulence. Furthermore, we have extended our investigations to relativistic shocks, that can be found in powerful extragalactic sources such as active galactic nuclei. We discuss the latest results of our relativistic shock simulations with pre-existing turbulence driven by proton cosmic rays.

Speaker: Karol Fulat

13:35 Turbulence driven by shock-clump interactions and particle acceleration in the turbulence

Cosmic rays (CRs) are believed to be accelerated via the first-order Fermi process, in which particles undergo scattering by magnetohydrodynamic (MHD) waves in the vicinity of a shock front. In the acceleration region of ultra-high-energy CRs, CR acceleration occurs in relativistic shocks, where the shock speed approaches the speed of light. To accelerate CRs to $10^{20}$ eV, the strong magnetic field turbulence around the relativistic shock is required (Lemoine et al., 2006; Niemiec et al., 2006). Understanding the nature of turbulence in the vicinity of the relativistic shocks is, therefore, crucial for elucidating the acceleration process.
The velocity field in the turbulence can be decomposed into solenoidal and compressive components. While solenoidal turbulence plays a key role in amplifying magnetic fields via dynamo action, both solenoidal and compressive modes contribute to the acceleration and scattering of high-energy particles. However, the relative importance of these modes in relativistic shock environments remains an open question.
In this study, we investigate turbulence generated by shock-clump interactions in relativistic shocks, where density inhomogeneities collide with the shock front. Performing high-resolution MHD simulations and the Helmholtz decomposition, we found that the compressive mode is excited to a comparable level of the solenoidal mode, which is not seen in the non-relativistic cases. In addition, we found secondary shocks which are generated by the shock-clump interactions and propagate in the downstream region. These secondary shocks introduce additional particle acceleration, potentially modifying the non-thermal energy spectrum produced at the main shock.
In this talk, we will present the results of our turbulence analysis and discuss in detail their implications for particle scattering and acceleration in relativistic shocks.

Speaker: Kanji Morikawa (The University of Tokyo)

13:50 Modifications to diffusive shock acceleration in the presence of density gradients

It has been a long-standing paradigm that the bulk of Galactic comic-ray gets accelerated at supernova remnant shocks via diffusive shock acceleration. As observations – both direct and indirect – became better, many features appeared in the cosmic-ray spectra at Earth and in the emission spectra of remnants, that require deviations from the expectation of a simple power-law of accelerated particles with a power-law index of s=-2.

Here, we demonstrate how the presence of a density-gradient in the upstream of a shock can lead to a hardening or softening of the resulting particle distribution, depending on the direction of the gradient. We show analytically and with numerical simulations, that the spectral modification is proportional to τacc/τgra, where τacc is the acceleration timescale of particles and τgra the typical timescale over which the upstream-density changes. An increasing density leads to a softening of the spectrum.

A gradient in ambient density in this sense can be created by a change of the abundancy of an element, e.g. in the medium inside a stellar wind-bubble. Here, the burning of hydrogen over time leads to an increasing hydrogen-fraction from the vicinity of the star towards the edge of the wind-bubble. We show that such spatial gradients, which differ in strength between elements, lead to differing spectral indices between different particle species. For a typical wind-bubble around a massive star, the result is a softer proton spectrum compared to helium, as observed for Galactic cosmic-rays.

Speaker: Robert Brose (University of Potsdam)

14:05 Impact of anisotropic diffusion and drifts on CR acceleration

Although for classical models of diffusive shock acceleration (DSA) at supernova remnants (SNRs) it is hard to reach PeV energies, SNRs are still believed to contribute a large amount of the total Galactic cosmic-ray luminosity. Nowadays it is clear that SNRs show a significant temporal evolution of those parameters relevant for the transport and acceleration of CRs within and the escape from them; the magnetic field for example can change from being mainly radial to tangential with increasing age of the SNRs. Thus, for an accurate description of CR acceleration over the lifetime of the source, time-dependent models are required, dropping the assumption of parallel shocks. At regions where the shock is oblique, drifts of CRs have to be taken into account. In the case of strong external magnetic fields, such as at SN 1006, the situation becomes even more interesting, drifts potentially drive CRs to regions where the shock is parallel and where DSA is most efficient.

We utilize a new generalized stochastic differential equation solver based on the open source propagation framework CRPropa to model time-dependent DSA in such potential Galactic cosmic-ray sources. We present models of DSA ranging from parallel to perpendicular spherical SNRs, including complex magnetic background fields. Furthermore, we consider anisotropic diffusion which allows CRs to cross magnetic field lines, facilitating DSA at almost perpendicular shocks at which otherwise shock drift acceleration takes over.

Speaker: Lukas Merten (Ruhr University Bochum, RAPP Center)

14:20 Cosmic Ray Acceleration via Turbulence-Induced Magnetic Reconnection: From Micro to Macro Scales

Turbulence-driven magnetic reconnection is increasingly recognized as a crucial mechanism for accelerating cosmic rays (CRs) to ultrahigh energies (UHEs) in magnetized astrophysical environments, ranging from compact sources to more extended regions. In this talk, I will provide an overview of this acceleration process and present a comparative analysis of 3D magnetohydrodynamic (MHD) and particle-in-cell (PIC) simulation results.
I will explore how cosmic ray acceleration unfolds across both microscopic and macroscopic scales, drawing insights from 3D PIC kinetic simulations, hybrid 3D MHD-PIC models, and large-scale 3D MHD simulations. While micro-scale simulations are essential for understanding the initial stages of particle acceleration—commonly referred to as the injection problem—macro-scale MHD models help determine the maximum energies particles can reach. I will discuss the key similarities and differences between these regimes, their influence on acceleration rates and spectral properties, and the transition from microscopic to macroscopic scales.
Furthermore, I will examine how 3D turbulent-reconnection efficiently accelerates particles to high energies in a Fermi-like process and its implications for astrophysical sources, particularly AGN accretion disks and jets. This mechanism offers a compelling explanation for the observed gamma-ray and neutrino emissions from magnetized regions. In particular, I will discuss applications to sources such as TXS 0506+056 and MRK 501 blazars, which have been associated with very high energy gamma-ray flares and neutrino detection.

Speaker: Elisabete de Gouveia Dal Pino

14:35 Supernova-like Collisionless Shock in the Laboratory

The study of collisionless shocks and their role in cosmic ray acceleration has gained importance through observations and simulations, driving interest in reproducing these conditions in laboratory experiments using high-power lasers. In this work, we examine the role of three-dimensional (3D) effects in ion acceleration at quasi-perpendicular shocks under laboratory-relevant conditions. Using hybrid particle-in-cell simulations (kinetic ions and fluid electrons), we explore how the Alfvénic and sonic Mach numbers influence ion energization and establish scaling criteria for when 3D simulations are necessary. Our results show that while 2D simulations suffice for most laboratory-accessible shocks, 3D effects become crucial for shock velocities exceeding 1000 km/s and experiments sustaining the shock for at least 10 ns. We surveyed previous laboratory experiments on collisionless shocks and found that 3D effects are unimportant under those conditions, implying that 1D and 2D simulations should be enough to model the accelerated ion spectra. However, we do find that these experiments are realistically close to accessing the regime relevant to 3D effects, an exciting prospect for future laboratory efforts.

Speaker: Luca Orusa (Princeton University)

13:20 → 14:50 CRI: phenomenology

13:20 A data-driven approach to identifying the sources of the most extreme energy cosmic rays

We use the reconstructed properties of individual UHECR events to constrain the location of their unknown sources via approximate Bayesian computation. All important propagation effects, including deflections in both Galactic and extragalactic magnetic fields, are implemented via CRPropa 3. We define priors over key parameters, the source position, distance, particle energy at the source, and extragalactic magnetic field properties, inferring constraints where possible and otherwise marginalising over uncertainties. This approach allows us to jointly consider selection effects due to both the particle energy and arrival direction, leading to a more self-consistent inference. We present our updated results for the Amaterasu particle, including the updated UF23 Galactic magnetic field model, and explore the impact of mass composition and energy scale uncertainties on the interpretation. Our results identify several candidate sources beyond the Local Void. We also discuss ongoing efforts to accelerate our inference method, enabling applications to larger event samples and higher-dimensional parameter spaces.

Speaker: Nadine Bourriche (Max Planck Institute for Physics)

13:35 Centaurus A as the main source of ultrahigh-energy cosmic rays

The possibility that a dominant fraction of the cosmic rays above the ankle is due the single source Centaurus A is discussed. We focus on the properties of the source spectrum and composition required to reproduce the observations, showing that the nuclei are strongly suppressed for E > 10Z EeV, either by a rigidity dependent source cutoff or by the photodisintegration interactions with the cosmic microwave background at the giant dipole resonance. The very mild attenuation effects taking place at lower energies imply that the secondary nuclei produced in photodisintegration processes during propagation from this nearby source provide a small contribution. Given the moderate anisotropies observed, the deflections in extragalactic and Galactic magnetic fields should play a crucial role. The diffusion in extragalactic fields as well as the finite source lifetime significantly affect the shape of the observed spectrum. The cosmic ray flux at tens of EeV is dominated by the CNO component, being actually better reproduced by a mixture of C and O nuclei rather than by just N, while heavier nuclei become dominant above 70 EeV. The cosmic ray flux at a few EeV should mostly result from a more isotropic light component associated with a population of extragalactic sources. The inclusion of the subdominant contribution of heavy nuclei from the Galactic component helps to reproduce the observations around 1 EeV.

Speaker: Esteban Roulet

13:50 On Acceleration of >100 EeV CRs in Novel Scenario of Magnetar Transients

The highest-energy cosmic rays (CRs) with energy above $10^{20}$ eV$=100$ EeV are one of the most mysterious particles in the Universe. Recently, Telescope Array Collaboration (2024) detected the second highest energy CR in history, $244\pm29{\rm (stat.)}~^{+51}_{-76}{\rm (sys.)}$~EeV, which is named as `Amaterasu.' Unger and Farrar (2024) reported no existence of candidates among the radio galaxies by cross-matching the astronomical source catalog and backtrack analysis of Amaterasu. They pointed out the most straightforward possibility that Amaterasu was accelerated in an astrophysical transient event in undistinguished galaxies. Moreover, the $\sim120^{+110}_{-60}$ PeV muons event, KM3-230213A, recently discovered by KM3Net Collaboration, implying the arrival of $35$-$380$ PeV cosmic neutrino (KM3Net Collaboration 2025). This event is thought to imply the existence of CR sources other than those responsible for lower-energy neutrinos because the estimated energy flux exceeds the flux in the lower-energy range observed by IceCube Collaboration. To explain the above observations, we need to consider the possibilities of CR acceleration processes in a broad sense, however challenging they may be.

Transient phenomena in magnetars have been considered as possible acceleration sites of CRs. However, the CR acceleration and the trigger mechanism of magnetar transients are still unclear. In particular, the ion injection mechanism is the most significant problem. Wada and Shimoda (2024) recently suggested a scenario for the activity that the magnetar's rotation axis suddenly flips due to the Dzhanibekov effect, resulting in a sudden rise of the Euler force. The material in the outer layer plastically flows due to the force and finally fractures in this scenario. We study the possibilities of ion acceleration along with this scenario and find that the electron stream from the fractured region possibly induces a strong electric field for a moment. The Fe-ions from the same fractured region can be accelerated by this electric field up to $\sim1$ ZeV within a timescale of $\sim1$ ps.

The nuclear spallation reactions limit the acceleration timescale, and therefore, high energy CR `neutrons' ($\sim$20 EeV) from the parenteral nuclei become proper observational predictions of this scenario: their arrival time and direction will be correlated with the bursting photon emissions of the host magnetars. The nuclear spallation of $\sim$ ZeV nuclei is preferred to explain $\sim100$ PeV neutrino events observed by IceCube and KM3Net.

In this presentation, we will review the novel scenarios of magnetar transients, iron-ion acceleration, and proper observational predictions of our model in the sense of multimessenger astrophysics.

Speaker: Dr Tomoki Wada (Department of Physics, National Chung Hsing University, Taichung, Taiwan)

14:05 A Galactic cosmic ray model that accounts for all the spectra and components data

Combining the CR measurements by AMS-02 and DAMPE in space and those by LHAASO and Auger on the ground, a Galactic cosmic ray model has been
constructed to recover all these measurements from tens of GeV to tens of EeV. The precise measurements of CR spectra for individual species by AMS-02 and DAMPE together with the newest LHAASO results clearly indicate three Galactic CR components, that is, a soft low-energy background, a hard high-energy component, and a local source contribution. The LHAASO data also show that above ∼10^16 eV, a
nonnegligible extra component, possibly of extragalactic origin, must be included. Combining the Auger results and the LHAASO results, we figure out the extragalactic CRs that need at least two components at lower and higher energies. The spectrum features and mass measurements in all energy ranges are all well reproduced in the model.

Speaker: Prof. Xiaojun Bi (Institute of High Energy Physics, Chinese Academy of Sciences)

14:20 The Role of the Heliosphere in Shaping the Observed Cosmic Ray Spectral Anisotropy

Experimental results by Milagro, HAWC, and ARGO-YBJ have observed variations in the energy spectrum of cosmic rays at TeV scales in different regions of the sky. These findings on the spectral anisotropy provide insights into cosmic ray behavior. This work explores the impact of galactic CR interactions with the heliosphere in creating the observed spectral anisotropy features. Specifically, the features around 1-10 TeV, where our previous studies on the heliosphere have shown the greatest effects. In this project, we integrate particle trajectories in a state-of-the-art MHD-kinetic heliosphere model that includes the effects of the solar cycle and interaction with the interstellar medium’s magnetic field. With these elements, this will be the first time the exact effects of the heliosphere’s magnetic field are tested to determine whether they influence galactic CRs and the spectral anisotropy.

Speaker: Dr Vanessa López-Barquero (University of Maryland College Park)

14:35 A Measurement Scheme of Anisotropy from quasi-2D to True 2D

Current experimental observations of true two-dimensional (2D) anisotropy are insufficient: ground-based experiments achieve precise measurements only in right ascension (RA), while space-based experiments currently provide solely upper limits. For ground detector arrays, the accuracy of detector efficiency is lower than the anisotropy amplitude. Most experiments adopt equal-declination (Dec) normalization to correct efficiency effect, but this method compromises the comparability between different Dec bands. To address this issue, we introduce an innovative rotating ground detector array scheme. By dynamically rotating the detector array, mutual calibration across different RA and Dec is enabled, which decouples the anisotropy from detector effect, thereby allowing direct measurement of true 2D anisotropy. Validation through toy Monte Carlo simulations confirms the method’s feasibility and demonstrates its extension to space-based experiments.

Speaker: Dan Li (Institute of high Energy Physics)

13:20 → 14:50 DM: indirect detection

13:20 Dark Matter Searches in Dwarf Galaxies with VERITAS

The nature of dark matter (DM) remains mysterious despite decades of indirect, direct and collider searches. Indirect searches for DM attempt to observe the gamma rays produced in DM decay or annihilation. Depending on the DM particle mass, these gamma rays may be in the very-high-energy regime (>100 GeV). The Very Energetic Radiation Imaging Telescope Array System (VERITAS), an imaging atmospheric Cherenkov telescope array, can detect gamma rays in an energy range of 100 GeV to >30 TeV and is therefore an ideal instrument for an indirect DM search. A popular target category for indirect searches is dwarf spheroidal galaxies (dSphs), due to their large inferred DM content. We present two searches conducted by VERITAS using observations of dSphs. In the first, we set constraints on wino and quintuplet dark matter models, using 638 hours of VERITAS observations of 17 dSph targets. In the second, we present recent observations of Ursa Major III, a recently discovered dSph. Ursa Major III has a predicted DM density that is ~2 times more than that of the next most DM-dense dSph, making it a particularly promising candidate for DM detection. We derive limits on the velocity-weighted annihilation cross section in a DM mass range of 200 GeV to 30 PeV.

Speaker: Conor McGrath (Queen's University)

13:35 Line emission search from Dark Matter annihilation in the Galactic Center with LST-1

Dark Matter (DM) remains a great mystery in modern physics. Among various candidates, the weakly interacting massive particles (WIMPs) scenario stands out and is under extensive study. The detection of the hypothetical gamma-ray emission from WIMP annihilation could act as a direct probe of electroweak-scale interactions, complementing DM collider searches and other direct DM detection techniques. At very high energies (VHE), WIMP self-annihilation is expected to produce gamma rays together with other Standard Model particles. The Galactic Center (GC), due to its relative proximity to the Earth and its high expected DM density, is a prime target for monoenergetic line searches. Imaging Atmospheric Cherenkov Telescopes (IACTs) have placed strong constraints on the DM properties at the GC, with the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) providing the most stringent limits from 20 TeV to 100 TeV exploiting Large Zenith Angle (LZA) observations. However, the limited field of view (FoV) of the MAGIC telescopes (< 3.5° ) prevented a detailed study of the extended region around the GC in which an enhanced DM density is expected.
The first Large-Sized Telescope (LST-1) of the Cherenkov Telescope Array Observatory (CTAO), located at the Roque de Los Muchachos Observatory (La Palma, Spain) close to the MAGIC site, has been observing the GC since 2021. With its wide FoV of 4.5°, LST-1 could contribute significantly to the WIMPs search at the GC. The observations are performed at LZA (ZA > 58°), which, while required due to the source's low altitude, also optimizes the detection of gamma rays up to 100 TeV and beyond. Here we present the first WIMP line emission search with LST-1. We provide a comprehensive study of the LST-1 instrument response functions for LZA observations and a detailed study of the background rejection in monoscopic observations. We present the most updated results based on simulated data demonstrating improved statistical analyses and new methodologies for spectral line search.

Speaker: Mr Abhishek Abhishek (University of Siena & INFN Pisa)

13:50 Search for gamma-ray spectral lines from dark-matter annihilation with the DAMPE satellite

The annihilation of dark-matter particles may lead to the production of monochromatic gamma-ray emission. In this contribution, the search for spectral lines in the gamma-ray spectrum using nine years of data collected with the space-borne Dark Matter Particle Explorer is presented. No line signal is found between 5 GeV and 1 TeV in several regions of interest. The constraints on the velocity-averaged cross-section of the neutralino annihilation are estimated for different dark-matter density profiles and compared with other experiments on ground and in space.

Speaker: Jennifer Maria Frieden (EPFL - Ecole Polytechnique Federale Lausanne (CH))

14:05 Searching for Axion-like Particles signatures in the M87 spectrum with HAWC

Exploring Dark Matter (DM) scenarios through the TeV emission from Active Galactic Nuclei (AGNs) has the potential to provide constraints on the existence of DM candidates such as the Axion-like Particles (ALPs). The very high-energy gamma-ray spectrum of nearby AGNs is expected to be attenuated due to pair production interactions with the Extragalactic Background Light (EBL). However, if photon-ALP oscillations occur in the presence of magnetic fields, some gamma rays could evade EBL attenuation, leading to an observable spectral signature. Previous observations of the radio galaxy M87 by multiple observatories at very high energies have shown that its energy spectrum extends above 10 TeV, making it a good candidate for placing constraints on the ALPs parameter space. The High Altitude Water Cherenkov (HAWC) observatory provides unique observations that could complement and extend the constraints on the ALPs parameter space with M87 serving as an excellent target for DM searches. This work presents exclusion limits on the ALP parameter space, obtained by analyzing seven years of HAWC data from M87, while accounting for systematic uncertainties associated with different EBL models.

Speaker: José Erandi Serna Franco (Instituto de Física, UNAM)

14:20 A 43 GeV gamma-ray line in the nearby galaxy clusters?

As the largest gravitationally bound object in the Universe, galaxy clusters are favorable targets for indirect dark matter (DM) search. The GeV-TeV gamma-ray line is the smoking gun signal of the DM annihilation/decay. From the 15.5 years' observation data of the nearby massive galaxy clusters by Fermi-LAT, we detect a tentative gamma-ray line signal at ~43 GeV. The line signal has a net TS value of ~30 in the directions of Virgo, Fornax, and Ophiuchus clusters, three massive clusters with the highest J-factors expected to generate the dark matter annihilation signal. The signal still presents when the data of another 10 nearby massive clusters have also been included, though the TS value decreases to ~21 likely because of their lower signal-to-noise ratios. We correct for the ‘‘look elsewhere effect’’, the global significance of the signal is ~4.3σ and ~3.7σ for the samples of three clusters and 13 clusters, respectively. We further discuss potential systematic effects in this search. However, this signal is absent in the inner Galaxy, which disfavors both the instrumental effect and the canonical dark matter annihilation interpretation, and a more sophisticated dark matter model or very peculiar astrophysical scenario might be needed.

Speaker: Dr Zhaoqiang Shen

14:35 Modeling of Dark Matter Prompt and Secondary Signatures in Dwarf Spheroidal Galaxies

Dwarf Spheroidal (dSph) galaxies are very promising laboratories for the indirect search for Dark Matter (DM), due to their low astrophysical background in radio and gamma-ray frequencies.

For the past several decades, the prompt emission from DM annihilation signatures has been explored through modeling and the setting of limits. In addition to the direct annihilation signatures from neutrinos, gamma-rays, electrons, positrons and antimatter, the secondary emission from radiation processes also contributes to the picture. For instance, synchrotron radiation and inverse Compton scattering of charged DM annihilation products such as electrons and positrons can provide a significant signal. The quantitative modeling of this secondary emission with the astrophysical background is necessary to place stringent constraints on the nature of DM.

In this work, the multiwavelength secondary spectrum of DM annihilation for dSph galaxies is calculated using the open-source code CRPropa 3.2., which allows for the self-consistent treatment of the astrophysical background and secondary emissions. We present a systematic comparison of signatures from conventional astrophysical processes to those expected from DM annihilation. The morphological differences between the two scenarios are investigated and tests of the impact of different magnetic fields, DM masses, and DM profiles are performed.

Speaker: Athithya Aravinthan (Ruhr University Bochum)

13:20 → 14:50 GA: AGNs

13:20 Multi-wavelenght view of 3C 279 during the 2017-2018 EHT campaigns including an unprecedented gamma-ray flare

Spinning super-massive black holes at the center of galaxies can launch powerful magnetized jets. When these jets are oriented within a few degrees of our line of sight, they are called blazars, active galactic nuclei that exhibit variable, non-thermal emission across the entire electromagnetic spectrum, from radio waves to gamma rays. 3C 279 is an archetypal blazar with a prominent radio jet that undergoes broadband flux density variations. In April 2017 and April 2018, the Event Horizon Telescope (EHT) observed 3C 279 with an unprecedented angular resolution of 20 microarcseconds. In parallel, an extensive quasi-simultaneous multi-wavelength (MWL) campaign was conducted using both ground- and space-based observatories, covering frequencies from radio wavelengths to the TeV energy range. Here, we present preliminary results from the first two EHT-MWL observational campaigns, including the detection of a record-breaking gamma-ray flaring episode seen by Fermi-LAT. Additionally, we provide initial interpretations based on the modeling of 3C 279's time-variable broadband emission and polarization using the Turbulent Extreme Multi-Zone (TEMZ) numerical framework.

Speaker: Giacomo Principe (University of Trieste)

13:35 Insight into the Jet Emission Properties from Long-Term Monitoring of the TeV Blazar PG 1553+113

PG 1553+113 is a distant TeV blazar known for its ~2.2-year periodic gamma-ray signal detected by Fermi. We present results from a decade-long, multiwavelength monitoring campaign of this source.
Our analysis confirms the periodicity in gamma-ray and optical bands; however, no significant periodicity is found at TeV and X-ray energies, based on observations with MAGIC and Swift-XRT, respectively. These findings, combined with a study of variability on different timescales, support a multi-zone emission scenario, as further corroborated by recent IXPE observations.
We test a two-zone, synchrotron self-Compton model on 2019 multi-frequency flare data. The long- and short-term variability, along with inter-band correlations from the monitoring, serve as key inputs to constrain the model, reducing the large degrees of freedom. Based on this approach, we propose a set of parameters that effectively describe the PG 1553+113 emitting region responsible for the observed radiation.

Speaker: Elisa Prandini (Padova University and INFN Padova, Italy)

13:50 Periodic Modulation of the Gamma-ray Flux Emitted by the Blazar PG 1553+113 Confirmed: Clues on the SMBH Relativistic Jet Mystery

We present the results of more than 15 years of Fermi Large Area Telescope (LAT) monitor observations of the high-energy peaked BL Lac object PG 1553+113 at E>100 MeV and E>1 GeV gamma-ray bands, in comparison with optical, radio and X-ray multifrequency monitoring data. A long-lived, 2.1-year periodic modulation, of the gamma-ray flux is continuing to be significant at a 4 sigma level against stochastic red noise, with about seven cycles. This doubles the total time range of data with respect to the previous work by the LAT Collaboration based on 6.9 years of data (Ackermann et al. 2015), where this periodicity was tentatively discovered. Independent determinations of oscillation period and phase based on data published in the earlier work and the new data are in agreement (chance probability <0.01). This cyclic behavior modulates the rapid-term and intermediate-term irregular variability and the flares of PG 1553+113. The discovery allows prospects for investigating pulsational accretion flow in a potential sub-parsec binary supermassive black hole system (binary SMBHs), or accretion flow instabilities, disk and jet precession, rotation or nutation and also perturbations by massive stars or compact objects in polar orbit around a single SMBH. We will show this gamma-ray blazar can represent a optimal case study for the understanding of the mystery of relativistic outflows and jets from SMBHs.

Speaker: Dr Stefano Ciprini (INFN Roma Tor Vergata)

14:05 Variability studies of the LHAASO triggered flares in blazar 1ES 1959+650

The blazar 1ES 1959+650 is one of the nearest TeV extragalactic sources to us. Its gamma-ray spectrum is very hard, with a spectral index of only around 1.9 in the GeV energy band reported in 3FHL (the 3rd Fermi-LAT high energy sources catalog). Years ago, a TeV orphan flare was discovered in this source, and it was considered a potential neutrino source. Shortly after the real-time transient monitoring system based on LHAASO-WCDA established at the end of 2023, a gammaray flare from 1ES 1959+650 was triggered (ATel #16437). In this talk, we will present the several flare events of this source in 2024 and study its variabilities at multi-wavelength. The rare TeV delay phenomenon may be strong evidence of particle acceleration process.

Speaker: Jianeng Zhou

14:20 Long-term observation of the blazars Mrk 501 by LHAASO

Long-term and unbiased monitoring of rapidly variable gamma-ray sources, such as active galactic nuclei (AGNs), is essential for elucidating the emission mechanisms behind these extragalactic objects. The Large High Altitude Air Shower Observatory (LHAASO), one of the largest ground-based experiments, provides valuable insights into very high energy (VHE) phenomena, enabling comprehensive studies of AGN physics. In this work, we present a long-term monitoring campaign of Markarian 501 (Mrk 501), a well-known BL Lacertae object. Over the past few years, Mrk 501 exhibited relatively quiescent behavior, with no significant flares or outbursts observed. Its long-term spectral energy distribution (SED), corrected for extragalactic background light absorption, is well described by a power-law function with an exponential cutoff. Our analysis reveals five notable outbursts, with durations ranging from 14 to 180 days, which we categorize into three distinct types. Notably, we identified a “harder when brighter” trend in its emission. Multi-wavelength observations from Fermi-LAT, MAXI, and Swift indicate a strong correlation between VHE gamma-ray and X-ray emissions, while the correlation with high-energy (HE) gamma rays is weaker. Furthermore, no significant time lags were detected between HE, VHE, and X-ray emissions

Speaker: Dixuan Xiao

14:35 Long-term multi-wavelength view and broad-band modeling of the blazar B2 1811+31 in high state

The intermediate synchrotron-peaked BL Lac B2 1811+31 (z=0.117) underwent a period of high activity from the optical band to very-high-energy (VHE; 100 GeV < E < 100 TeV) gamma rays in 2020. Following a high-state detection by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope in the high-energy gamma-ray band (HE; 100 MeV < E < 100 GeV), a dedicated multi-wavelength (MWL) campaign from radio to VHE gamma rays was organized. In this campaign, the MAGIC Telescopes detected for the first-time VHE gamma-ray emission from the source and the broad-band emission was precisely characterized. To put this high state into the context of the source long-term emission, we employed an extensive MWL dataset spanning over 18 years from the radio and optical/UV bands to X rays and HE gamma rays.
In this contribution, we present the long-term MWL behaviour of B2 1811+31, with particular emphasis on the high state. We resolve long-term correlated evolution on timescales ranging from years to weeks in the optical and HE gamma-ray band, as well as variability on timescales of few hours at HE gamma rays during the highest activity period. We observed a significant shift of the synchrotron peak frequency during the flaring activity, which led the source to a borderline state between intermediate and high synchrotron-peaked BL Lac. We discuss the evolution of the source MWL emission in terms of particle acceleration and cooling within multiple regions active in the jet and propose a self-consistent leptonic model to interpret the broad-band emission during the high state.

Speaker: Davide Cerasole (Universita e INFN, Bari (IT))

13:20 → 14:50 GA: SNR & PWN

13:20 Unveiling a Binary system’s Supernova Aftermath: A Cosmic Duel of Hadronic & Leptonic Gamma Rays from the IC 443 complex region

Despite IC 443 being among the most studied Galactic supernova remnants (SNRs) across the entire electromagnetic spectrum, the complex region around it has yet to be clarified. A detailed analysis of IC 443 surroundings yielded the detection of extended GeV gamma-ray emission spatially coincident with the G189.6+3.3 SNR. Despite the lack of a complete radio continuum image, the position and morphology of the gamma-ray emission, detected using 16 years of Fermi-LAT data, clearly matches the newly detected G189.6+3.3 X-ray shell with eROSITA, constituting compelling evidence for the gamma-ray emission origin. This study examines regions of the remnant potentially interacting with the S249 HII cloud to determine if gamma-ray emission originate from the same or different particle populations. The northeastern region, coinciding with a molecular cloud and a conspicuous Hα filament, shows spectral curvature best described by a LogParabola model. In contrast, the southeastern region, not overlapping with the molecular cloud, exhibits a steeply rising gamma-ray spectrum, resembling an inverse Compton (IC) peak near TeV energies. Such evidence make G189.6+3.3 SNR the first example of an SNR that actively demonstrates how interaction with molecular gas triggers hadronically induced gamma-ray emission from its regions overlapped with the molecular cloud, whereas its regions that are free of molecular gas emit leptonically induced gamma-rays. Furthermore, its interaction with the S249 HII cloud is evidenced by both the hadronic origin of the gamma-ray emission from the northern part of the remnant and the precise spatial correlation of the latter component with a conspicuous Hα filament. Combined with the morphology analysis results, this correlation strongly supports gamma-ray production through proton (re)-acceleration via adiabatic contraction within the filament and positions G189.6+3.3 at the same distance as IC 443, lending support to the hypothesis of a binary system in which both components underwent supernova events.

Speaker: Miltiadis Michailidis (HEPL, KIPAC, Stanford University)

13:35 Gamma-Ray Insights into Galactic SNRs: Fermi-LAT Detection of Kes 78, G032.4+00.1, and the PeVatron candidate PWN G32.64+0.53

G032.8-00.1 (or Kes 78) and G032.4+00.1 are two adjacent (in projection) supernova remnants (SNRs), apart by 0.4 deg. Both remnants have been investigated in the radio and X-ray bands. Both were previously considered to be related with the 2FGL J1850.7-0014c gamma-ray source. However, such an association was abandoned in the latest Fermi-LAT catalogs. The current view supports the detection of a GeV gamma-ray excess from this location, but its origin is uncertain.

In this work, we employ 16.2 yr of Fermi-LAT data to investigate the gamma-ray emission from this region. As such, we provide the first comprehensive morphological and spectral analysis of the gamma-ray emission from the location of the two remnants from which we infer that they are the best candidates among the sources known to date for explaining the detected excess, which exhibits two distinct maxima. We detect gamma-ray emission from both SNRs >1 GeV at a 9 sigma significance level. The spectral shapes obtained, best described by a LogParabola, together with the apparent interaction of the remnants with nearby molecular gas, supports a hadronically induced gamma-ray emission scenario for both remnants. This finding is further corroborated by the results of the multiwavelength spectral energy distribution (SED) modeling conducted in this study. This discovery adds G032.4+00.1, which is also one of the most distant Galactic SNRs ever detected, to the closed group of Galactic SNRs; only a handful of such objects have been detected, which are established gamma-ray emitters with a non-thermal spectral component in the X-ray band.

In addition, this work reports the first statistically significant detection at the 4.5 sigma level in the GeV energy band with Fermi-LAT for the nearby PeV candidate pulsar wind nebula PWN G32.64+0.53 associated with pulsar PSR J1849-0001.

Speaker: Miltiadis Michailidis (HEPL, KIPAC, Stanford University)

13:50 Discovery of Very-High-Energy gamma-ray emission from SNR G108.2-0.6 by LHAASO

An extended Very-High-Energy (VHE) gamma-ray source coincident with the location of the large radio shell-type SNR G108.2-0.6 is newly discovered by LHAASO. With no excess gamma-ray emission above 100 TeV, the source energy spectrum is well fitted by a power-law function, implying no obvious cutoff. The VHE gamma-ray observation of this extended source has revealed a large shell-type structure with similar position and extension as SNR G108.2-0.6, thereby confirming their association. CO observations by MWISP indicate little spatial correspondence between MCs and SNR G108.2-0.6. A detailed analysis of Fermi-LAT observations is also carried out. Based on preliminary results from LHAASO and multi-wavelength observations, SNR G108.2-0.6 may belong to a class of TeV SNRs, where three prototypes are RX J1713.7-3946, RX J0852.0-4622 and SN 1006. Fermi-LAT data are used together with LHAASO data to discuss the possible origin of the gamma-ray emission, either via leptonic or hadronic scenarios.

Speaker: Sha Wu (IHEP)

14:05 Radio detection of SNR G310.7–5.4 with gamma-ray counterpart

Supernova remnants (SNRs) are known to accelerate particles up to relativistic energies. We have recently discovered a new SNR, G310.7-5.4 at high Galactic latitude using the ASKAP’s EMU and POSSUM surveys at 943.5 MHz (Burger-Scheidlin et al., in prep.). The faint, extended object has an apparent size of 30.6′ × 30.6′ and shows the typical SNR bilateral shell structure. Strong linear polarisation is detected from the bilateral shell regions, showing an opposite sign rotation measure indicative of a toroidal magnetic field. It is also one of the faintest known radio SNRs. Furthermore, a spatially coincident gamma-ray source is detected, indicating that the SNR could be accelerating particles to high energies.
SNRs at high Galactic latitudes, such as the one presented here, have received attention in recent years as more of them are detected off the Galactic plane. Discovering these objects together with their gamma-ray counterparts can put a new perspective on such sources as these SNRs are expanding in rather unperturbed, low-density environments, with diminished risk of source confusion. This allows to study cosmic ray (CR) acceleration and constrain CR models. Compiling a representative sample of this group of SNRs can allow to deduce their general properties. We have therefore put together a list of such sources, currently comprising a dozen objects to compare their properties such as size, energy flux and photon spectral index. Some of these SNRs may also be good targets for the upcoming, next-generation Cherenkov Telescope Array Observatory (CTAO).

Speaker: Mr Christopher Burger-Scheidlin (Dublin Institute for Advanced Studies DIAS)

14:20 A Search for High Energy Emission from the Remnant of Supernova 1181

Over the past millennium, only five Galactic supernovae have been observed and recorded by contemporary astronomers, and their current-day counterparts subsequently identified. The remnants of four of these have all been very deeply studied, and ultimately detected, by TeV instruments after exposures of typically hundreds of hours. The measured TeV fluxes range from 1 Crab (by definition) down to 0.3% Crab. The location of the fifth supernova remnant tied to a historical record of its supernova (SN 1181) has never been studied at TeV energies. The reason for this is simple – the associated remnant was only identified as such in 2021. The remnant, Pa 30, is an unusual object whose properties are best explained as resulting from a Type Iax supernova explosion. These are a rare sub-type of Type Ia supernovae in which the merging white dwarfs are not fully destroyed by the supernova explosion, leading to a double-degenerate merger product colorfully described as a “zombie star”. We will present the results of a search for TeV gamma-ray emission from Pa 30 with VERITAS.

Speaker: Jamie Holder (University of Delaware)

14:35 Hints for variable gamma-ray emission from the Galactic SNR RCW86

Supernova remnants are known to accelerate particles to relativistic energies on account of their non-thermal emission. Fast variability in the non-thermal synchrotron emission has been detected in multiple remnants and was linked to local properties of the magnetic fields. Further, variations in the long-term radio and x-ray flux have been reported for various objects as well.
RCW86 is one of the objects with variability of the non-thermal X-ray emission from a small localized region. It is a young Galactic SNR interacting asymmetrically with the outer shell of a wind-blown bubble created by a progenitor’s or companion’s wind. Analysis of the multi-wavelength observation of RCW86 from radio to gamma-ray energies lead to the conclusion that its gamma-ray emission is likely of leptonic origin.
Here, we report indications for a variability of the gamma-ray emission of RCW86 in the high-energy domain. We analyzed 16years of LAT-data at energies above 10GeV and find a flux-variation in one part of the remnant with a probability of ≤1% of obtaining such a result by chance. We found no evidence for unexpected or systematic variability of the gamma-ray emission of other sources in the field of view.

Speaker: Robert Brose (University of Potsdam, Germany)

13:20 → 14:50 OE

Convener: Anastasia Tezari (CERN)

13:20 IPPOG’s Success Stories : a Portal to Colliders & Cosmic High Energy Particle Physics Outreach

The International Particle Physics Outreach Group was created, about 30 year ago, to foster public engagement in STEM via the development of “hands on data” activities. The International Master Class programme underwent, since then, a spectacular and steady growth.

However, IPPOG was also setup as a « Forum » where national outreach programs and actors could share information, inspiration, and gain visibility through a common report. Its founders had from the beginning the ambition to build an inclusive and worldwide network, from colliders and medical applications to neutrinos and cosmic rays observatories. A dream that came gradually true, as IPPOG now groups 33 countries, 6 experiments, 3 national and international laboratories.

In 2017 IPPOG became a formal Collaboration, driven by MoU signed by institutional bodies such as funding agencies, universities, scientific collaborations. The IPPOG Forum meets twice a year in spring (in one of the countries) and in fall (at CERN). It offers the possibility to present any project and activity through « Sucess stories ».

The mechanisms put in place by the collaboration will be illustrated by examples. The web portal which is currently under development will be presented.

Speaker: Claire Adam Bourdarios (Centre National de la Recherche Scientifique (FR))

13:35 Teachers and Students educational activities based on cosmic muons in France

Cosmic muons are a concrete way to introduce the physics of the “infinitely small” in high schools. In France, despite the adverse evolution of the school curriculum in science that has limited the room for this subject in teaching, some teachers and students have developed a wide range of educational activities that are presented during classes or in the context of scientific circles, both as concrete applications of mathematical concepts (statistics, uncertainties, etc.) and, examples to raise awareness about science.

Building around various tools provided by scientists (educational detectors, public datasets, documentation, patronage or mentoring, etc.), these teachers and students have imagined and implemented innovative projects, often in relation to their environment; designed new equipments and proposed related experiments adapted to classroom teaching; encouraged novel pedagogical interactions between researchers and students, etc.

Such creativity is remarkable, given the lack of resources and the limited time that teachers can dedicate to such long-term projects. The goal of this talk is to present a selection of these realizations, and to share the enthusiasm and dedication of these people who truly act as “multiplicative factors” between our science and the society as a whole.

Speaker: Dr Nicolas Arnaud (IJCLab (Université Paris-Saclay and CNRS/IN2P3))

13:50 Storytelling strategies for multimessenger astrophysics

Multimessenger and astroparticle astrophysics has revolutionised our way of observing the cosmos, through electromagnetic and gravitational waves, and astroparticles. The way we take and analyse data, and therefore make science, has been changed, so it’s time to bring this change to our communication strategies and the stories we tell.

This field of research exerts on the general public the fascination of Astronomy and, at the same time, stimulates the curiosity of fundamental physics. Probably also for this reason, it enjoys considerable popularity: discoveries and results, concerning this field of research, are often in the limelight of global communication.

This popularity offers a range of unprecedented opportunities for outreach and communication, but also of course greater complexity in planning and managing these activities at all levels: from site visits and events for the large public to the production of content for social media and national and international media relations. What narratives and contents could allow the general public to approach this field, be part of its progress, but also be aware of the uncertainty of knowledge processes? How to manage confidential information within such large groups? How to manage the contradiction between the reality of scientific research as a collective effort and the need for personalization for example on social media? Focusing on recent moments in the public communication and Outreach activities concerning gravitational waves (and developed by Virgo and EGO, also in a global context) could probably help to shed light on the contemporary issues of communication of fundamental research.

From the other side we will present how EGO and the Virgo outreach group have explored in recent years various ways of telling this story to the public. The aim of the panel is to discuss what strategies can be used to talk about multimessenger astrophysics and the frontiers of astrophysical observations to different targets, with a specific focus on live events and performances. Some examples are the development of the theatre play “The Maps of the Cosmos”, telling the stories of some of the people who made the history of astronomy, through a multimessenger lens; “The Sound of the Universe”, live conversation about the frontiers of multisensorial and multimessenger astrophysics, with a focus on inclusion of people with disabilities and “Exploring the frontiers of the cosmos”, panel on multimessenger astronomy with musical performances.

Speaker: Mr Guglielmo Rossi (European Gravitational Observatory (EGO))

14:05 Citizen science to enhance sub-GeV neutrino searches in IceCube

Machine learning has become a vital part of analysis in modern neutrino astronomy, and many recent discoveries would not be possible without it. This approach, however, is limited by the quality of available training data. Located at the South Pole, the IceCube Neutrino Observatory is a neutrino detector sensitive to astrophysical neutrinos from GeV to PeV energies, with ongoing efforts to push the sensitivity down to 100 MeV for neutrinos from transient events. IceCube is dominated by massive backgrounds, detecting more than 10 billion atmospheric muons for each astrophysical neutrino, and machine learning is a powerful tool to reduce this large background rate. However, undetected outliers in labelled training data negatively affect the final performance of machine learning algorithms. Citizen scientists can help to quantify and qualify outliers in IceCube data to improve the detection of such outliers. In this contribution, we present the ongoing effort of utilising citizen science to improve a machine-learning-based event selection targeting sub-GeV astrophysical neutrinos.

Speaker: Gwenhaël Wilberts Dewasseige (UCLouvain)

14:20 Bringing Research Infrastructure to the Public: an outreach case study from the CERN Science Gateway

Astrophysics and particle physics both rely on large-scale, complex research infrastructures—from space telescopes and observatories to underground detectors and particle accelerators. While both fields explore fundamental questions about the universe, they also share a common challenge in public engagement: how to make highly technical and abstract science accessible, meaningful and interactive.

Recent initiatives, such as integrating a working particle accelerator into a museum, demonstrate how laboratory-based sciences can create direct and engaging experiences for non-specialist audiences. However, successful public engagement with complex scientific instruments requires more than simply displaying the technology (Bain & Ellenbogen, 2002; Molinié & Boudia, 2009; Gauvin, 2016). Interactive storytelling, live demonstrations and clear contextualisation are essential to making research infrastructure accessible and to fostering deeper public involvement(Meyer, 2011; Hampp & Schwan, 2015; Derolez, 2020).

ELISA, a functioning proton accelerator at CERN’s Science Gateway, provides a valuable case study of how real scientific instruments can enhance outreach and education. By allowing visitors to witness real-time scientific processes, ELISA fosters engagement through live demonstrations and participatory learning. However, integrating such an instrument into a museum setting presents challenges, including technical constraints and audience engagement strategies.

This presentation reflects on ELISA’s implementation while drawing from best practices in outreach and education research. It explores how scientific infrastructures, regardless of discipline, can be integrated to foster greater public participation and appreciation of fundamental
and applied sciences. By addressing the challenges and opportunities of integrating research instruments into science communication, this work provides guidance for institutions seeking to include functional scientific infrastructure to create richer and more immersive public engagement experiences.

References
Bain, R., & Ellenbogen, K. (2002). Placing Objects within Disciplinary perspectives: Examples from History and Science. In G. Scott, Perspectives on Object-Centered Learning in Museums. Routledge.
Derolez, S. (2020). Instrument de la « big science » et biographie culturelle. Culture & Musées. Muséologie et recherches sur la culture, 36, Article 36.https://doi.org/10.4000/culturemusees.5781
Gauvin, J.-F. (2016). Functionless : Science museums and the display of « pure objects ». Science Museum Group Journal. https://doi.org/10.15180.160506
Hampp, C., & Schwan, S. (2015). The Role of Authentic Objects in Museums of the History of Science and Technology : Findings from a visitor study. International Journal of Science Education, Part B, 5(2), 161-181. https://doi.org/10.1080/21548455.2013.875238
Meyer, M. (2011). Researchers on display : Moving the laboratory into the museum. Museum Management and Curatorship, 26(3), 261-272. https://doi.org/10.1080/09647775.2011.585800

Speaker: Annabella Zamora (Université de Lausanne)

14:35 Will art tell the story of science? Dialogues between art and science on frontier topics in fundamental physics

Increasingly, the major themes of scientific and technological research (and even of fundamental physics, from discoveries at particle accelerators to the new gravitational and multimessenger astronomy), inspire the work of contemporary artists. The dialogue between art and science is one of the most innovative and promising frontiers of contemporary culture. Artistic interpretation and reworking of scientific content can often succeed in illuminating aspects and meanings that are 'collateral’, and not immediate for the scientists themselves, but which can be of great impact for society and other communities and audiences.
Artistic research can contribute to the construction of a new shared cultural imaginary related to the new horizons opened up by frontier research, for example, of the new vision of the Universe, which physicists and Astronomers have constructed in the last century and which has continued to transform dramatically in recent decades.
In particular, the dialogue path developed in recent years by the European Gravitational Observatory (EGO) and the National Institute of Nuclear Physics (INFN) with several artists, well known in the international scene, will be described. This has focused on some discoveries (on the borderline between fundamental physics, astronomy and astrophysics) that have revolutionized, since the beginning of the last century, the way we observe the cosmos: from the discovery of cosmic rays to the discovery of gravitational waves, from astroparticle observations to the revolution in multimessenger astronomy. Some of the most significant milestones of these collaborations are the exhibition “Gravity. Imagining the Universe after Einstein” at the MAXXI in Rome, 2017, “The Rhythm of Space”, at the Museum of Graphics in Pisa in 2018, “Uncertainty. Interpreting the Present, Predicting the Future”, 2021 that involved internationally renowned artists such as Tomas Saraceno, Laurent Grasso, Liliane Liyn, Allora & Calzadilla and others.
With the same approach, the European Gravitational Observatory has developed in recent years a program of residencies and collaborations with young artists, such as Lulù Nuti, Pedro Torres, Alice Paltrinieri, Attila Faravelli, Massimo Magrini...
The inspiring idea of this path was presented during the public program of the Italian Pavilion at the Venice Art Biennale 2024, while some works were presented at the Spoleto Festival dei due Mondi 2024 and at the Genoa Science Festival, Bergamoscienza and others...
In addition to presenting the process and outcome of these collaborative experiences, it is intended to propose a more general reflection on the method and approach deployed in the interaction between scientists and artists; to discuss how contemporary art interprets problematic nodes or major research innovations with unprecedented aesthetic imagery and the fact that these artistic researches and the parallel initiatives of contemporary art museums or 'hybrid' cultural centers are in fact experimenting with new formats of communicating science, broadening its perspective and values.

Speaker: vincenzo napolano (European Gravitational Observatory - EGO - Italy)

13:20 → 14:50 SH: energetic events

13:20 Extreme Solar Energetic Particles Events measured by the Alpha Magnetic Spectrometer.

After thirteen years of operations on board the International Space Station, AMS has performed precise measurements of solar energetic particle (SEP) mostly observed during solar maximum of solar cycle 24 and 25. AMS has collected more than 40 extreme SEP events accelerated during M- and X-class flares and associated with fast coronal mass ejections. AMS detects these SEPs in the GV rigidity range with fine rigidity resolution at percent level accuracy. A summary of these events, with details on the latest SEPs observed in 2024, will be presented.

Speaker: Cristina Consolandi (University of Hawai'i at Manoa (US))

13:35 Survey of Fe-rich SEP events observed by Parker Solar Probe/Integrated Science Investigation of the Sun

The observed composition of solar energetic particle (SEP) events can be influenced by a number of factors, including the acceleration mechanism, transport effects, and properties of the particle seed population. Generally the abundances of heavy ions relative to oxygen are higher in events where the dominant acceleration mechanism is flare-associated reconnection as compared to events where the particles are primarily accelerated by shocks driven by coronal mass ejections (CMEs). Occasionally, large shock-accelerated SEP events exhibit significant enhancements of ions such as Fe reminiscent of those found in reconnection-related events. Whether these enhancements are a result of the acceleration conditions (e.g., properties of the shock and/or seed population) or a contribution of flare-associated SEPs is still debated. Data from the Integrated Science Investigation of the Sun (ISʘIS) on Parker Solar Probe provides a unique opportunity to examine these events at radial distances significantly inside 1 AU. Here we present results from a survey of such Fe-rich SEP events observed by ISʘIS and discuss their characteristics in comparison to observations made at 1 AU.

Speaker: Christina Cohen

13:50 Active regions with super-productivity in Solar Energetic Particles

An average solar active region (AR) does not usually generate any enhancement in Solar Energetic Particles (SEPs) near Earth. A small subset of regions are able to produce one or a few SEP events and these are typically taking place at times of fairly good magnetic connection with near-Earth locations via the interplanetary magnetic field (IMF). However a small minority of ARs are super-productive in SEPs, generating events throughout their solar passage on the disk, as viewed from Earth, from eastern to western longitudes. An example is AR 10930, active in December 2006, which produced GLE 70 but also two eastern SEP events. Another is AR 5747, generating three GLEs in October 1989. This presentation will compare the features and particle events of several SEP-super-productive ARs and identify any commonalities. Here super-productivity is defined in terms of the high energy (~100 MeV) proton component of SEPs, which is the most important for Space Weather. Properties of the associated solar flares and Coronal Mass Ejections will be considered to identify how these may have contributed to super-productivity. A discussion of whether specific features of the IMF and magnetic connection may have facilitated propagation of the energetic particles to Earth will be presented.

Speaker: Silvia Dalla (University of Central Lancashire)

14:05 Observations and simulations of decay phases of Solar Energetic Particle events

The properties of solar energetic particle (SEP) event profiles have been researched extensively to investigate the acceleration and transport of SEPs. The effects on SEP intensity profiles of particle-filled magnetic flux tubes corotating with the Sun are generally considered to be negligible. However, corotation has recently been suggested to have an effect on SEP decay phases, based on results of test particle simulations. This is expected to be dependent on the location of the observer with respect to the active region (AR) associated with the event.

To determine if corotation effects are discernible in observations, we analyse multi-spacecraft observations of SEP intensity profiles from 11 events between 2020 and 2022, using data from Solar Orbiter, Parker Solar Probe, STEREO-A, and SOHO. We also aim to study how the properties of the flares and coronal mass ejections (CMEs) associated with the events affect the parameters of the decay phase.

Using 3 energy channels; electrons $\sim$1 MeV, protons $\sim$25 MeV, and protons $\sim$60 MeV, we derive the decay time constant, $\tau$, and study the dependence of $\tau$ on the longitudinal separation, $\Delta \phi$, between the source active region and the spacecraft’s magnetic footpoint on the Sun.

We find that within individual events there is a tendency for $\tau$ to decrease with increasing $\Delta \phi$: test particle simulations show that this is a signature of corotation, not present when the latter is neglected. Thus we conclude that corotation has an effect on the decay phase of an SEP event and should be included in simulations and interpretations of these events.

We characterise the magnitude of the solar event that produced the SEPs using the intensity of the associated flare, speed of the associated coronal mass ejection and SEP peak flux as proxies. Our results show that the magnitude of the solar event influences the measured $\tau$ values and are likely the cause of the observed large inter-event variability, along with varying solar wind and interplanetary magnetic field conditions.

Further we introduce a new methodology to incorporate turbulence-induced perpendicular scattering within 3D test particle simulations in an approximate way. At randomly generated times the particle’s position is displaced in the direction perpendicular to the interplanetary magnetic field according to a prescribed distribution. We compare the results of simulations including this implementation of perpendicular scattering with those that neglect it, with emphasis on differences in the decay phase and on how corotation effects vary between the two types of simulations.

Speaker: Ruth Hyndman

14:20 Study of solar activity with AERA at the Pierre Auger Observatory

Solar activity events release vast amounts of energy,
including radio waves, X-rays, ultraviolet radiation, and energetic
particles, which interact with the Earth's ionosphere and can disrupt radio
wave propagation, affecting radio communications. They can either
enhance reflections, enhancing long-distance terrestrial communications,
or cause signal degradation and absorption, respectively depending on
whether the increased ionization affects the upper or lower layers of
the ionosphere. In the first case, the solar cycle modulates the Maximum
Usable Frequency (MUF), the highest frequency usable for radio
communication between two Earth-based points. The Auger Engineering
Radio Array (AERA) of the Pierre Auger Observatory was developed to
measure the radio emission from extensive air showers in the 30-80 MHz
band. We examine the impact of solar activity on AERA data collected
over approximately 11 years. We report the detection of different types
of solar radio bursts and we investigate how increased solar radiation -
particularly in the X-ray and extreme ultraviolet bands - also affects
measurements in the AERA energy band. Our results show a remarkable
correlation between the MUF and the broadband noise observed in the
30-40 MHz frequency range. Radio blackouts are also observed in AERA
spectrograms in coincidence with those reported by the National Oceanic
and Atmospheric Administration (NOAA). These findings highlight the
complex interplay between solar activity and radio wave propagation,
which is also relevant for cosmic-ray detection.

Speaker: Rogerio Menezes

14:35 Observations of Solar Gamma-Ray Flares by ISOIS/EPI-Hi/HET on Parker Solar Probe

The ISOIS/EPI-Hi/HET instrument on Parker Solar Probe can detect neutrals if they interact in the instrument and produce a charged particle (e.g., a gamma ray Compton scattering to produce an electron) when that particle stops in a shielded central region of silicon detectors without triggering the surrounding guards or outer detectors. A background of gamma rays is continuously created when high-energy galactic cosmic rays interact with material in the spacecraft or instrument, and this background increases when solar energetic particles (SEPs) also generate such locally produced gamma rays. A solar gamma-ray flare can be distinguished from this background provided the neutral rate increases significantly before the arrival of SEP particles. In a preliminary survey of the neutral rate data we have found at least 7 gamma-ray flares to date, ranging in duration from <1 minute to ~15 minutes, with intensities as high as ~100 times the quiet-time background level. The largest gamma-ray flare yet seen at Parker occurred on 20 May 2024 and was associated with an x-ray flare estimated to be GOES class X16 as observed at Solar Orbiter. The source region, AR13664, had earlier produced the tremendous May 2024 geomagnetic storm but had rotated to the far side of the Sun (as seen from Earth) by this time and was no longer geoeffective. We present time profiles and energy spectra of the HET solar gamma ray observations, describe the associated SEP events, and compare with X-ray, radio, and other observations in these events where available.

Speaker: Richard Leske

14:50 → 15:20 Coffee

15:20 → 16:50 CRD: acceleration

15:20 Non-thermal particle spectra from Fermi acceleration at oblique magnetised shocks

We revisit the process of particle-acceleration at magnetised shocks having an oblique large scale magnetic field. We find the surprising result that even in the test-particle limit, curved spectra may be produced.

For many years, diffusive shock acceleration (DSA) has been viewed as one of the central mechanisms to accelerate cosmic rays (CRs). It is applied to many astrophysical scenarios, such as supernova remnants (SNRs), and is regarded as the main acceleration mechanism for CRs in the galaxy. Therefore, the spectrum obtained with DSA is used as the injection spectrum for CRs to model their spectrum observed at Earth, after transport through the galaxy.

One of the key predictions of DSA is that it produces power laws, that depend on only a single parameter, namely the compression ratio of the shock. Extending this result to oblique shocks, where the upstream magnetic field is not aligned with the shock normal, is, however, not trivial, as the assumption of a nearly isotropic distribution function breaks down in the neighbourhood of the shock.

To capture the resulting anisotropies, we use Sapphire++ (https://sapphirepp.org), a code that simulates CR propagation and acceleration. We find that even in the test-particle limit, curved spectra are produced. Discussing how energy-dependent scattering can affect the spectra and thereby the spectral index, we observe different spectral indices in various energy regimes, producing curvature in the spectra. Furthermore, we discuss the impacts of spatially dependent scattering on the spectra.

Speaker: Florian Schulze (Max-Planck-Institut für Kernphysik)

15:35 Uncovering Electron Acceleration Mechanisms in Quasi-Parallel Shocks using First-Principles Simulations

Collisionless shocks are widely recognized as powerful particle accelerators in space and astrophysical environments, contributing significantly to the nonthermal energy budget across the universe. A fundamental challenge is understanding how collisionless shocks, where Coulomb interactions are negligible, accelerate thermal particles into a nonthermal energy state, leading to a power-law distribution spanning several orders of magnitude in energy. While the primary acceleration mechanism, diffusive shock acceleration (DSA), is well established, no existing theory succeeds in explaining the electron injection process into DSA.
To investigate this, we have conducted a comprehensive study of electron acceleration in non-relativistic quasi-parallel shocks using first-principles kinetic Particle-In-Cell simulations. Our investigation covers an unprecedented range of shock parameters: shock speeds 0.067−0.267c, Alfvén Mach numbers 5−40, sonic Mach numbers 5−160, and proton-to-electron mass ratios 16−1836. We identify the conditions required for electron injection into DSA and the acceleration efficiency of these nonthermal (cosmic ray) electrons for different shock parameters.
In this talk, I will present the key results from our investigation. I will focus on the mechanisms of electron acceleration and the critical role of self-generated plasma instabilities in electron injection and nonthermal energy evolution. I will also introduce a minimal model to illustrate these results. Our study provides essential insights for developing subgrid models of nonthermal processes at shocks, which are important for the accurate interpretation of nonthermal radiation, including radio, X-ray, and gamma-ray emission from Earth's bow shock to supernova remnants and other galactic/extragalactic sources.

Speaker: Siddhartha Gupta (Princeton University)

15:50 Diffusive shock acceleration of dust grains at supernova remnants

Diffusive shock acceleration (DSA) is a prominent mechanism for energizing charged particles up to very large rigidities at astrophysical collisionless shocks. In addition to ions and electrons, it has been proposed that interstellar dust grains could also be accelerated through diffusive shock acceleration; for instance, at supernova remnants (SNRs). Considering interstellar dust grains of various sizes and compositions, we investigate the possibility of grain acceleration at young SNR shocks (throughout the free expansion and Sedov-Taylor phases) and the maximum energies reached by the accelerated grains. We investigate the potential implications for the abundance of refractory species relative to volatile elements in the cosmic-ray composition. We find that the acceleration of dust grains at relativistic speed is possible, up to a Lorentz factor of ∼102 and a kinetic energy of Ek/nuc ∼ 102 GeV/nuc for the smaller grains of size a ∼ 5 × 10‑7 cm. We find that the subsequent sputtering of grains can produce nuclei with a sufficient rigidity to be injected in the process of diffusive shock acceleration. Such a scenario can help naturally account for the overabundance of refractory elements in the Galactic cosmic-ray composition, provided that a fraction, η ∼ 10‑3 ‑ 10‑2, of dust grains swept up by an SNR are energized through DSA.

Speaker: Pierre Cristofari (Observatoire de Paris)

16:05 Collisionless shock in a relativistically hot and unmagnetized plasma

Collisionless shocks in relativistically hot ($T \gg mc^2$) plasmas are investigated using the Particle-In-Cell (PIC) simulation. Shocks in space are collisionless shocks, which are mediated by wave-particle interactions rather than the Coulomb collisions. Considering the upstream temperature, shocks can be classified into two types: cold upstream ($T \ll mc^2$) and relativistically hot upstream ($T \gg mc^2$). Shocks in relativistically hot plasmas are thought to exist in the universe such as the internal shock model of gamma-ray bursts, the lobe of radio galaxies, and the downstream of a shock in a density inhomogeneous region because the downstream of a shock with relativistic velocity is relativistically hot. However, there are few kinetic simulation studies of such shocks, and we don't know how efficiently particles are accelerated, how strong magnetic fields are generated, or even whether a shock is formed as collisionless.
We elucidate the kinetic properties of shocks in unmagnetized electron-positron relativistically hot plasmas using the PIC simulation.

1. Shocks mediated by the Weibel instability are formed consistent with the Rankine-Hugoniot relation.
2. With appropriate standardization, kinetic properties such as the strengths and wavelengths of the magnetic fields and the energy spectrum are almost independent of the upstream temperature, even as the temperature becomes relativistically hotter and hotter.

Our simulation results can be understood by considering so-called the relativistic beaming effect. Our results can be applied to various high-energy astrophysical phenomena and the cosmic ray acceleration processes.

Speaker: Kazuki Kamiido (The University of Tokyo)

16:20 Efficient electron and ion acceleration and heating at oblique magnetised mildly relativistic shocks

Mildly relativistic collisionless plasma shocks allow for a broader range of oblique subluminal mean magnetic field configurations, in contrast to inherently superluminal ultra-relativistic shocks. This enables particle acceleration and heating mechanisms, as well as the generation of electromagnetic waves, driven by particle reflection off the shock. Here, we present our recent results from large-scale particle-in-cell (PIC) simulations of mildly relativistic magnetised shock waves in ion-electron plasmas. Our study examines two configurations: an oblique shock with an obliquity angle just below the critical angle and a quasi-parallel shock. We show that in the oblique configuration a shock transition is characterised by a train of magnetosonic waves with very strong longitudinal electrostatic gradients. The resulting electrostatic potential efficiently traps electrons and ions, enabling their acceleration via the E×B drift. Particles repeatedly bounce within the wave, gaining very high energies over multiple cycles. In the quasi-parallel shock configuration large-amplitude coherent waves form in the upstream region and are further amplified in the reflected hot ion beam region. Interactions of ions and electrons with these waves lead to their efficient heating to relativistic temperatures. These results are applicable to jets of Active Galactic Nuclei and microquasars, where sites of intense nonthermal X-ray and gamma-ray emission are often associated with mildly relativistic shocks. Our findings also highlight previously unexplored mechanisms for the generation of high-energy cosmic rays in relativistic astrophysical jets.

Speaker: Gabriel Torralba Paz (Institute of Nuclear Physics Polish Academy of Sciences)

16:35 PIC Simulation of a Relativistic Shock Propagating to Electron, Proton, and Heavy Ion Plasmas

Chemical abundances in cosmic rays (CRs) are crucial for understanding their origin and acceleration mechanisms. Shock waves formed in high-energy astrophysical phenomena are promising mechanisms for CR acceleration. The chemical composition of the medium through which the shock propagates differs in each high-energy astrophysical phenomenon. Observational experiments of CRs show that the chemical composition of cosmic rays exhibits enhancements compared to solar abundances. This could be attributed to the chemical composition of their origin and even the potential dependence of acceleration efficiency on ion species. Previous particle-in-cell (PIC) simulations of relativistic shocks have primarily focused on plasmas with a single ion species. However, in relativistic shocks propagating through multispecies-ion plasmas, the acceleration mechanisms of each ion and electron remain unclear. In this study, we present the first PIC simulation of a relativistic shock propagating in an electron-proton-helium plasma. We find that even in an environment with a solar-like chemical composition, helium ions, despite their lower initial abundance, can be accelerated as efficiently as protons and may even dominate the high-energy region of the cosmic-ray energy spectrum at the source. Additionally, we analytically derive the injection fraction of helium ions, which is consistent with our simulation results. We also find that the acceleration fraction depends on the upstream helium ion fraction. Since ions with the same charge-to-mass ratio follow similar trajectories, our results can be extended to other heavy elements. Our findings are consistent with the chemical composition of ultra-high-energy CRs observed by the Telescope Array and Auger (Batista et al. 2019). Finally, we discuss the implications of high-energy heavy ions for high-energy neutrino emissions.

Speaker: Sara TOMITA (Chiba University)

15:20 → 16:50 CRI: phenomenology

15:20 A Data-driven Heavy-Metal Scenario for Ultra-High-Energy Cosmic Rays

The mass composition of ultra-high-energy cosmic rays is usually inferred from the depth of the shower maximum (Xmax) of cosmic-ray showers, which is ambiguously determined by modern hadronic interaction models. We examine a data-driven scenario in which the expectation value of Xmax is considered as a free parameter. We test the hypothesis of whether the cosmic-ray data from the Pierre Auger Observatory can be interpreted in a consistent picture under the assumption that the mass composition of cosmic rays at the highest energies is dominated by high metallicity, resulting in a pure iron composition at energies above ≈40 EeV. We investigate the implications for astrophysical observations and hadronic interactions, and discuss the global consistency of the data assuming this heavy-metal scenario.

We find that the publicly-available data of the Pierre Auger Observatory can be interpreted consistently if the expectation values for Xmax from modern hadronic interaction models are shifted to deeper values. The resulting shifts of the predicted Xmax scale closely match those obtained from joint fits of Xmax and the ground signal distributions in the 3 EeV − 10 EeV range [PRD 109 (2024) 102001] and might be explained by recent improvements in air-shower modelling. Consequently, the changes in the mean and variance of ln A shift the measured data at 3 EeV − 100 EeV well within the region of expected combinations of protons and He, N, and Fe nuclei, contrary to the standard interpretation using unmodified model predictions. The variance of ln A is then consistent with the model-independent constraints on the broadness of the cosmic-ray mass composition at energies 3 EeV − 10 EeV in [PLB 762 (2016) 288].

In the presented scenario, the flux suppression of cosmic rays is consistent with a rigidity cutoff approximately at 2 EV. Consequently, the disappearance of nitrogen and iron nuclei from the cosmic-ray beam at the same rigidity could explain the instep feature of the cosmic-ray energy spectrum. The muon deficit predicted by the QGSJet II-04 and Sibyll 2.3d models is alleviated from ∼30% − 50% to ∼20% − 25% when compared to the direct measurements of the muon signal. There is no indication that the inelastic p-p cross-section or elasticity needs to be modified in the two models within the heavy-metal scenario to describe the tail of the measured Xmax distributions.

Considering the observed dipole anisotropy of cosmic rays above 8 EeV, we confirm that this observation is consistent with a possible extragalactic dipolar distribution of cosmic-ray sources within the heavy-metal scenario at the 2σ level and even at 1σ level for very high extragalactic amplitudes (above ∼40%). Assuming only iron nuclei, the arrival directions of the most energetic Auger events, when backtracked through the Galactic magnetic field, point towards the Galactic anticenter region, consistent with the expectations from isotropic arrival directions at Earth. The estimated luminosity density of the sources in the heavy-metal scenario suggests that only very powerful objects, such as hard X-ray AGNs, could explain the origin of the ultra-high-energy cosmic rays.

Speaker: Alena Bakalova

15:35 UHECRs: a CRISP image of the origins

In the ultra-high-energy range, cosmic rays (UHECRs) can originate from distances as large as a few hundreds of megaparsecs, limited mainly by interactions with the infrared background light and the cosmic microwave background. Although a modest size, such volume may contain too many sources to be able to discern the origin with the capabilities of current observatories. Furthermore, the deflections caused by extragalactic magnetic fields (EGMFs) may further blur the arrival directions after some propagation distance. However, cosmic rays of extreme energies (ExECRs) may have much shorter disintegration lengths (depending on the mass) and thus are a strong indication of nearby sources in the range of a few tens of megaparsecs. We establish a neighboring volume with the largest potential for the discovery of UHECR sources based on the observational constraints and the observed ExECRs. The radial constraints are defined by the nuclear species observed at Earth and the composition evolution. Well defined distances are achieved with the package CRISP that computes the probability distributions describing the nuclear disintegrations caused by interactions during propagation. The angular constraints are established by models of the galactic magnetic field and the observed composition. The robustness of the results is estimated by determining the impact of factors like the photonuclear cross sections and the EGMF properties. The required specifications for observatories of ExECRs are provided.

Speaker: Leonel Morejon (Wuppertal University)

15:50 MHD Modes in the ISM: A Statistical Approach Using Synchrotron Polarization

Magnetohydrodynamic (MHD) turbulence plays a fundamental role in shaping the interstellar medium (ISM), influencing cosmic ray transport, star formation, and plasma dynamics. However, identifying the dominant MHD modes—Alfvén, slow, and fast—from observational data remains a significant challenge. In this study, we present a novel refinement of the Synchrotron Polarization Analysis (SPA) method to systematically diagnose the energy fractions of different MHD modes using synchrotron polarization statistics.

We begin by establishing a theoretical framework for how MHD modes imprint distinct statistical signatures onto the Stokes parameters of synchrotron radiation. We derive a revised SPA+ method that improves mode classification by incorporating an advanced fitting procedure. Using 3D ideal MHD simulations with various plasma parameters and turbulence driving mechanisms, we generate synthetic synchrotron polarization observations to test our methodology. Our findings reveal that the SPA+ method successfully distinguishes between Alfvén-dominated and compressible (slow-mode) dominated turbulence based on the symmetry properties of the polarization variance function $s_{xx}(\phi_s)$.

A major advancement of this study is the introduction of a new asymmetry parameter, which enables the identification of fast-mode turbulence—a crucial component previously undetectable using standard SPA techniques. We demonstrate that fast modes exhibit distinct asymmetry signatures in synchrotron statistics, particularly at large mean magnetic field inclination angles ($\theta_\lambda > 45^\circ$). This discovery provides a valuable observational tool for probing the presence of fast modes in the ISM, which has critical implications for cosmic ray acceleration and plasma dynamics. We further assess the robustness of the SPA+ method against Faraday rotation (FR) effects in both the emitting plasma and the foreground. Our analysis confirms that identification of compressible and fast modes remains reliable even in the presence of FR, making the method applicable to real observational data.

Overall, this study enhances our ability to classify MHD turbulence in astrophysical plasmas, providing a robust observational framework for characterizing MHD mode fractions using synchrotron polarization data. The detection of fast modes in particular offers new opportunities for understanding cosmic ray interactions and high-energy astrophysical processes. Identifying regions with compressible mode dominated turbulence could also potentially explain CR models that predict large CR scattering efficiency.

Speaker: Parth Deepak Pavaskar (DESY Zeuthen, Uni Potsdam)

16:05 Cosmic Rays: The Hidden Architects of the Circumgalactic Medium

Cosmic rays (CRs) remain a key uncertainty in galaxy evolution due to their poorly constrained transport and acceleration in diverse plasma environments. They may play a crucial role in shaping the multiphase structure of the Circumgalactic Medium (CGM), with their impact varying across different phases depending on their transport properties and coupling with the thermal plasma. A central question is how CRs might affect different CGM phases and whether CR pressure support may be dynamically significant. In this talk, I will discuss the influence of CRs on both the cold and hot phases of the CGM. I will present results from a suite of idealized simulations of a Milky Way-type host galaxy with varying satellite distributions, incorporating CRs from supernovae into both the host and satellite galaxies. I find that CR pressure enhances the surface area of ram pressure-stripped cool satellite clouds, boosting cooling in turbulent mixing layers and thereby prolonging cloud survival and increasing the cold-phase covering fraction. Conversely, I find that the CRs cannot efficiently heat gas to super-virial temperatures. I will also present results from new simulations exploring the dynamics of CR-driven shells and super-bubbles on a variety of scales in and around star-forming galaxies. Overall, these findings highlight the potential importance of CRs on galaxy ecosystems and how uncertainties in CR transport properties map to uncertainties in their importance.

Speaker: Manami Roy (The Ohio State University)

16:20 Unveiling the Nature of the Cosmic Ray All-particle Spectrum Knee by LHAASO-KM2A

The nature of the cosmic ray all-particle spectrum knee has been a long-standing puzzle since its discovery. The high altitude near the shower maxima of cosmic rays in the knee region has enabled the LHAASO experiment to conduct calorimetric energy measurements, significantly reducing the dependence of energy measurement on cosmic ray composition and interaction models typical in ground-based experiments. The all-particle energy spectrum and mean logarithmic mass have been measured with unprecedent precision. By introducing a novel concept called the total logarithmic mass, which is highly sensitive for evaluating the proton contribution to the knee, along with a cocktail method that allows for a natural light composition, the cosmic ray all-particle spectrum knee has been attributed to proton and helium, featuring rigidity-dependent cutoff energy with remarkable significance.

Speaker: Prof. Huihai He (Institute of High Energy Physics, CAS)

16:35 New Global Spline Fit - data-driven model of the cosmic-ray flux and mass composition from 1 GeV to $10^{11}$ GeV

The Global Spline Fit (GSF) is a data-driven parameterization of cosmic-ray flux and mass composition. It combines direct and indirect measurements of the cosmic-ray flux of individual elements from 1 GeV to $10^{11}$ GeV, considering their uncertainties. At lower energies, the fluxes are corrected to the local interstellar spectra using the individual data-taking periods of the experiments. The systematic energy scale uncertainty for each experiment is treated as a nuisance parameter and minimized jointly with other model parameters, thus matching the flux from indirect measurements above the knee to direct measurements below the knee region.
Since the original work was presented in 2017, many new measurements have been published by both direct and indirect cosmic-ray experiments. This presentation shows an updated GSF, including datasets from the last eight years. We assess the mutual compatibility and demonstrate the impact of the newly added data on the all-particle flux and mass composition over 11 decades in energy.

Speaker: Ralph Richard Engel (KIT - Karlsruhe Institute of Technology (DE))

15:20 → 16:50 DM: indirect detection

15:20 Exploring Dark Matter in Galaxy Clusters with MeerKAT: South Africa's powerful radio telescope at the forefront of astronomy

Current radio interferometers, with their high sensitivity and angular resolution, are uniquely positioned to investigate the predicted faint signals arising from Weakly Interacting Massive Particles (WIMPs). Among the most powerful instruments in the southern hemisphere is MeerKAT, a precursor to the Square Kilometre Array (SKA), which offers world-leading capabilities for probing dark matter through radio observations.

In this study, we leverage data from the MeerKAT Galaxy Cluster Legacy Survey to investigate galaxy clusters as promising candidates for detecting WIMP signals. Our approach combines a cutting-edge dark matter modeling tool with advanced radio astronomy techniques to probe the WIMP parameter space. We present competitive upper limits on the WIMP annihilation cross-section in galaxy clusters, spanning over three orders of magnitude. %Our results are superior to those produced with gamma-ray experiments, such as Fermi-LAT and HESS.
These results represent a significant advancement, providing new insights into the search for dark matter through galaxy clusters.

This presentation will discuss the challenges of comparing predicted WIMP-induced radio emissions with actual measured fluxes from galaxy clusters. A particular focus will be on the importance of using processed images versus raw visibility data—an issue that will become increasingly critical as the large data volumes produced by the SKA demand more computationally efficient analysis and interpretation strategies.

Speaker: Natasha Lavis (SARAO, University of the Witwatersrand)

15:35 Search for dark matter around intermediate mass black holes with the H.E.S.S. experiment

Intermediate mass black holes (IMBHs), with masses ranging from a hundred and a million solar masses, are hypothesised to be surrounded by dense regions of dark matter known as dark matter spikes, where the annihilation of dark matter particles could produce detectable gamma rays. The detection of dark matter annihilation around IMBHs therefore offers a promising approach for probing the nature of dark matter. In this work, we search for dark matter annihilation around IMBHs using data from the Galactic Plane Survey, the Extragalactic Survey and a selection of satellite galaxies observed by the H.E.S.S. gamma-ray experiment in Namibia. Since no evidence for a gamma-ray signal from dark matter annihilation around IMBHs has been found, we set upper limits on the velocity-weighted annihilation cross section for dark matter masses between 1 TeV and 100 TeV. Our analysis obtains limits on the velocity-weighted annihilation cross section below the thermal relic cross section for dark matter masses between 10 and 100 TeV.

Speaker: Prof. Manuela Vecchi (Kapteyn Astronomical Institute, University of Groningen)

15:50 Constraints on Dark Matter from Mini Spikes Around Stellar-Mass Black Holes Using Fermi-LAT Observations

The quest to identify the true nature of dark matter remains one of the most pressing challenges in modern physics. We present here a novel approach to probe DM by analyzing mini spikes in DM density around stellar mass black holes using 14 years of data from the Fermi Large Area Telescope (Fermi-LAT). These mini spikes, formed due to the adiabatic growth of black holes in DM halos, can significantly enhance the gamma-ray flux from DM annihilation. We derive upper limits on the gamma-ray flux from these regions using Fermi-LAT observations and calculate the corresponding J-factors to constrain the DM annihilation cross section. This technique provides a new and sensitive method to explore DM properties, particularly in the mass range of ∼10 GeV to ∼10 TeV. Our results complement existing DM searches and offer a unique window into the behavior of DM in extreme astrophysical environments. This approach, combined with future observations, has the potential to significantly advance our understanding of DM annihilation and its implications for particle physics and cosmology.

Speaker: Ana Vitoria de Almeida Martinheira Braga (Instituto de Física de São Carlos - Universidade de São Paulo)

16:05 Prospects of Axion-like Particles searches with the Southern Wide-field Gamma-ray Observatory (SWGO)

The Southern Wide-field Gamma-ray Observatory (SWGO) is a planned very-high-energy gamma-ray observatory that will provide novel and complementary insights about the southern-hemisphere sky thanks to its high sensitivity, wide field of view, and continuous observation capabilities. Centaurus A (CenA) is an Active Galactic Nucleus that has been detected at TeV energies by the H.E.S.S. observatory and has shown complex spectral features, challenging simple explanations based on the synchrotron self-Compton model. Among the proposed explanations for these features is the potential influence of Axion-like Particles (ALPs), hypothetical particles that could oscillate into photons in the presence of magnetic fields, leading to distinctive modifications in the gamma-ray spectrum. If photon-ALP oscillations occur, SWGO could detect characteristic spectral distortions in CenA’s gamma-ray emission. Conversely, the absence of such features would allow SWGO to set more stringent constraints on the ALP parameter space. This work presents exclusion limits on the ALP parameter space derived from simulated five-year observations of CenA with SWGO, highlighting the observatory’s capability to refine current constraints and contribute to the search for new physics.

Speaker: Rubén Alfaro (Instituto de Física, UNAM)

16:20 Modelling the unknown with CTAO: Investigating indirect WIMP dark matter search systematics

Dark matter is one of the most important and elusive enduring mysteries of physics in the last century. Gamma ray astronomy offers a possible avenue to determine dark matter’s particle nature through observation of gamma ray by-products of its annihilation or decay. However, it is challenging to formulate a robust dark matter search given our lack of knowledge on dark matter physics. In this talk, I describe a robust, flexible framework that can describe a large number of models. In order to achieve this, we model the final state output contributions and differential J factor maps in a model-independent way using future data from the Cherenkov Telescope Array observatory.

Speaker: Liam Pinchbeck (School of Physics and Astronomy - Monash University)

16:35 Probing WIMP Dark Matter with the Southern Wide-field Gamma-ray Observatory (SWGO)

Despite compelling astrophysical and cosmological evidence for dark matter (DM), its fundamental nature remains a mystery. We present sensitivity estimates for detecting DM particles using the next-generation Southern Wide-field Gamma-ray Observatory (SWGO), a very-high-energy gamma-ray facility under development in the Southern Hemisphere. SWGO will be sensitive to gamma rays in the energy range of hundreds of GeV to hundreds of TeV and will search for gamma-ray signals from DM annihilation or decay across key astrophysical targets, including the Galactic halo and several dwarf galaxies, notably the promising Reticulum II. With a wide field of view and long exposures, such an observatory will have unprecedented sensitivity to DM in the mass range of ∼100 GeV to a few PeV. These results, combined with those from other present and future gamma-ray observatories, will likely probe the thermal relic annihilation cross section of Weakly Interacting Massive Particles (WIMPs) for all masses from ∼100 TeV down to the GeV range in most annihilation channels.

Speaker: Aion Viana (IFSC-USP)

15:20 → 16:50 GA: AGNs

15:20 A Systematic Search for Spectral Hardening in Gamma-ray Blazars

Blazars are among the most powerful gamma-ray emitters, displaying rapid variability and extreme spectral properties. In this study, we systematically search for the most extreme high-energy blazars using 12 years of Fermi Large Area Telescope data, aiming to identify instances of spectral hardening in their gamma-ray spectra. This phenomenon is characterized by a flux that decreases with energy up to a break in the GeV range, after which the spectrum hardens as the flux begins to rise. While previous studies have reported spectral hardening in a few individual sources, this work presents the first dedicated, systematic analysis of this effect. We examine hundreds of blazars with high synchrotron peak frequencies from the 4FGL-DR2 catalog, detecting flaring periods using two methods based on Bayesian Block Analysis. Our results reveal a select population of blazars undergoing pronounced spectral hardening during flares, highlighting some of the most extreme gamma-ray accelerators known. These flares show a broader duration distribution than the general blazar population, suggesting that spectral hardening is more likely to occur in long-lasting flaring episodes. The observed spectral hardening could arise from a transition between synchrotron and inverse Compton emission, multiple emission zones in the jet, changes in particle acceleration, or even hadronic contributions. These findings refine the observational characterization of extreme blazars and lay the groundwork for future multi-wavelength and very-high-energy studies to better understand their variability and underlying physical mechanisms.

Speaker: Mrs Adithiya Dinesh (Universidad Complutense de Madrid)

15:35 Singular Spectrum Analysis of Fermi-LAT Blazar Light Curves: A Systematic Search for Periodicity

Blazars show variability across the entire electromagnetic spectrum and over a wide range of timescales. In some cases, characteristic emission patterns have been observed, such as the multi-year modulation detected in PG 1553+113. Quasi-periodic oscillations (QPOs) can arise from various astrophysical mechanisms, including jet precession, accretion disk instabilities, and binary supermassive black holes. While the latter is a particularly compelling possibility, potentially linking galaxy mergers to jet physics, the other scenarios also provide valuable information about the physical processes governing blazar variability, which remain poorly understood.

In this work, we present the first application of Singular Spectrum Analysis (SSA) to a large sample of Fermi Large Area Telescope (LAT) blazars in a systematic search for QPO candidates. SSA effectively isolates periodicity by decomposing the signal into trend, oscillatory, and noise components, providing a robust approach for characterizing variability. In addition, we provide forecasting models based on SSA to predict the long-term behavior of blazars. Our analysis identifies 46 blazar candidates for QPOs, including 25 new candidates not previously reported. This constitutes the largest sample of blazar QPO candidates to date, significantly surpassing previous studies and enabling the first steps toward population-level statistical analyses of these phenomena. By identifying promising candidates and highlighting their potential significance within the context of blazar variability, this study provides a foundation for future investigations into their physical origins.

Speaker: Alba Rico (Clemson University)

15:50 Revisiting the rapid VHE gamma-ray flare of PKS 2155-304 in a multi-blob model

Blazars, a subclass of active galactic nuclei (AGN), are known as the strong emission and frequent activities. The blazar PKS 2155-304 is a high synchrotron-peaked BL Lac with redshit $z=0.116$. On 2006 July 28, an extremely remarkable outburst of VHE $\gamma$-ray emission was reported by H.E.S.S from this blazar, with an average flux more than 10 times the quasi-stable-state value. On the other hand, the variability of the extraordinary outburst is as short as ~200 s, leading to the so-called "Doppler factor Crisis". To figure out the origin of this outburst, we focus on a multi-blob model and try to account for both the quasi-stable and flaring states in the blazars in the same framework. In our model, the emission of blazars consists of two components. One component comprises the emission of numerous blobs with weak dissipation along the jet. The other component arises from a few more powerful blobs that could randomly appear in any position of the jet, probably due to stronger dissipation or enhancement of Doppler factor. We show that the model is capable of explaining the quasi-steady state emission and the flaring state emission in terms of both spectrum and lightcurve with a modest Doppler factor. The obtained parameters may shed some lights on properties of the relativistic jet.

Speaker: Hongbin Tan (Nanjing University)

16:05 Beaming Effect and Relativistic Jet Characteristic in Fermi-era-Blazars

In this talk, I will review our recent progress and important findings of the beaming effect and relativistic jet property in gamma-ray blazars detected by the Fermi-Large Area Telescope (Fermi-LAT). Blazars are a particular class of radio-loud Active Galactic Nucleus (AGNs), characterized by many distinctive observational properties, which are due to the relativistic beaming effect. Since the beaming effect is not observable and the origin of jets is still not clear, we proposed several methods to reveal these important issues from different perspectives, based on our derived large sample of Fermi blazars. Principally, we come to the results and conclusions as follows:

(1) We present an effective method by means of the beaming effect to estimate four crucial parameters, including the upper limit of central black hole mass M, the Doppler factor , the location of γ-ray-emitting region Rγ, and the propagation angle with respect to the axis of the accretion disk , for more than 800 gamma-ray blazars. We put forward an updated demarcation between BL Lacertae objects (BL Lacs) and flat-spectrum radio quasars (FSRQs) based on the relation between broad-line region luminosity and disk luminosity both measured in Eddington units, i.e., L$_{\rm disk}$/L$_{\rm Edd}$ = 4.68x10$^{-3}$, indicating that there are some differences between BL Lacs and FSRQs on the accretion power in the disk. Besides, for the first time, we proposed a so-called “appareling zone”, which stands for a potential transition field between BL Lacs and FSRQs where changing-look blazars may reside. We found five confirmed changing-look sources in our sample that are lying in this zone.

(2) We made use of information from emission lines, spectral energy distributions, and the beam radio luminosity to study the jet power, black hole mass and spin. Our results suggest that BL Lac jets are powered by extracting BH rotation energy, while FSRQ jets are mostly powered by accretion disks. We also claim that the launching of the relativistic jet is dominated by the Blandford-Znajek process for both FSRQs and BL Lacs.

(3) By adopting a two-component model of emission within jets, we successfully separated the emission of radio, X-ray, GeV and TeV into beamed and unbeamed contributions for the largest sample of Fermi blazars up to now. Our results suggest that the emission is mainly from the core/beamed component in gamma-ray blazars.

Speaker: Prof. Zhiyuan Pei (Guangzhou University)

16:20 Estimating the Potential of the Cherenkov Telescope Array Observatory to Measure the Luminosity Function of Very-High-Energy Blazars

The Cherenkov Telescope Array Observatory (CTAO) is the next-generation ground-based observatory for gamma-ray astronomy, covering a very broad energy range from 20 GeV to beyond 100 TeV. The luminosity function (LF) of very-high-energy (VHE) blazars measures their evolution over cosmic time, constrains their contribution to unresolved radiation fields, and connects them to source populations measured in different wavebands and with other messengers. In particular, Fermi-LAT has measured the LF of blazars in the high-energy range. In this work, we probe the potential of CTAO to reconstruct a VHE blazar LF in the context of the CTAO extragalactic survey, a key science project which will include an unbiased observation of 25% of the sky. To simulate populations of VHE blazars, we generate VHE blazar populations by randomly sampling fluxes from BL Lac LFs, assigning each source a power-law spectral shape, and extrapolating to higher energies while accounting for absorption by the extragalactic background light. To assess CTAO's capability to reconstruct these simulated LFs through Markov Chain Monte Carlo sampling, the study incorporates both its Northern and Southern arrays, accounting for telescope effects based on the instrument response functions of the alpha configuration. This configuration refers to the first construction phase with an array of 4 Large-Sized Telescopes (LSTs) and 9 Medium-Sized Telescopes (MSTs) in the northern site (CTAO-North), and 14 MSTs and 37 Small-Sized Telescopes (SSTs) in the southern site (CTAO-South). These results will provide key information into the feasibility of measuring the VHE blazar LF with CTAO, helping to refine expectations for its extragalactic survey and its contribution to our understanding of blazar populations.

Speaker: Luiz Augusto Stuani Pereira (Universidade de São Paulo, Instituto de Física (IFUSP), São Paulo, Brazil)

16:35 Observation of BL Lac VER J0521+211 with LHAASO-WCDA

VER J0521+211 is one of the brightest BL Lac objects detected in the TeV gamma-ray regime, located at a redshift of z=0.108 and 3 deg away from Crab Nebula.It was not included in 1LHAASO catalogue, but manifests with 5.6 sigma in 978-day data from March 2021 to Jan 2024. WCDA enables continuous long term monitor, which will provide important information of the average emission of this blazar as IACT observations were often biased towards flaring periods. We present a detailed energy and morphology study of this blazar with LHAASO-WCDA, and analyzed the correlation between LHAASO and Fermi light curve.

Speaker: Sergio Hernández Cadena (Tsung Dao Lee Institute, Shanghai Jiao Tong University)

15:20 → 16:50 GA: SNR & PWN

15:20 Probing particle transport in the vicinity of Vela X using the H.E.S.S. array

The Vela SNR region is a bright, nearby and complex region of non-thermal emission which at its centre it contains a powerful pulsar and its associated pulsar wind nebula, commonly known as Vela X. Due to its nature as one of the most local cosmic ray accelerators it has been an object of interest for many studies at the highest energies.

We present a new detailed study of VHE gamma-ray emission in the Vela X region using over 200 hours of observations from the H.E.S.S. array of imaging atmospheric Cherenkov telescopes. This rich dataset allows us for the first time to study and observe changes in the gamma-ray spectral properties across the Vela X region, in particular measuring a lower energy cutoff in the diffuse region surrounding the central PWN. H.E.S.S. results are combined with multi-wavelength observations, most importantly X-ray observations from eROSITA to allow a detailed insight into particle acceleration and propagation within this nearby energetic region.

Speaker: Robert Daniel Parsons (Humboldt University of Berlin)

15:35 Are TeV-PeV observations unveiling the full extent of particle escape in pulsar-powered sources ?

Our exploration of the sky at the highest photon energies has recently benefited from a number of major advances, notably the expansion of the spectral window up to the PeV range, the probing of emissions over larger and larger angular scales, and the coverage of significant portions of the Galaxy. Such a broad view can be expected to lead to significant progress in our understanding of the life cycle of Galactic cosmic rays, from their acceleration in localized astrophysical sites to their release in the vicinity of sources and subsequent merging into a large-scale galactic population. Somewhat surprisingly, though, a large number of TeV-PeV sources display rather large angular extents and appear positionally coincident with pulsars. The physical connection seems viable from energetic, spectral or population arguments. In this contribution, I investigate the hypothesis that a number of the known TeV-PeV sources consists in pulsar-powered systems in which electron-positron pairs plays a major role.

I will introduce a framework for the dynamical and radiative evolution of a pulsar wind nebula inside a supernova remnant, incorporating particle escape across the different components of the system, from the nebula to the remnant and out to the interstellar medium. The model predicts a number of interesting features like the fact that pairs escaped into the remnant can be a significant if not dominant contribution to the emission from the system and may even dominate the pion-decay radiation from cosmic rays accelerated at the forward shock; or the possibility that in evolved systems, the TeV–PeV radiation from particles escaped into the interstellar medium can exceed by far that of the plerion. I will then explore to which extent such a description of pulsar-powered non-thermal sources is consistent with the properties of known Galactic sources, with a specific focus on the bright and very extended sources observed with LHAASO at the highest gamma-ray energies.

Speaker: Pierrick MARTIN (CNRS/IRAP)

15:50 Searching for escaped cosmic rays from supernova remnants using Fermi-LAT data

The origin of cosmic rays has been an active area of research since their discovery over a century ago. Supernova remnants (SNRs) are believed to be able to accelerate cosmic rays up to the ‘knee’ of the observed cosmic-ray spectrum. Although the acceleration at SNR shocks has been extensively modelled, it is still not clear that cosmic rays are able to escape these sources. After acceleration, cosmic rays may escape the shock front and diffuse into the surrounding environment where they could interact with ambient gas to produce gamma rays. Detection of gamma-ray emission outside the observed shell of an SNR will provide evidence for cosmic-ray escape from SNRs. In this contribution, we will outline an approach to search for escaped cosmic rays from SNRs using Fermi-LAT data. We will discuss our methods to perform both a morphological and spectral analysis for a SNR. We also look for a spatial correlation between the observed gamma rays and surrounding molecular clouds. We will present preliminary results for a selection of Galactic SNRs, including W28. We aim to use these results to perform multi-wavelength spectral modelling for the SNRs and investigate the possible hadronic or leptonic origin of the gamma-ray emission.

Speaker: Jemma Pilossof (The University of Adelaide)

16:05 Observation of cosmic-ray acceleration and escape from SNR W44 by LHAASO

We present the analysis of 4 year LHAASO data of the middle-aged SNR W44 and the massive mocecular gas complex that surrounds it. We confirm the presence of the extended gamma-ray structure located near the remnant. Based on the high-resolution gas maps, we demonstrate that gamma-ray structures are caused by the interaction of escaped relativistic particles with Moclecular Clouds。We argu that the revealed cosmic-ray "clouds" suggest an anisotropic character of the escape of high energy particles frem the shell.

Speaker: Hanrong WU (IHEP)

16:20 Stereo observations of CTA 1 with SST-1M

CTA 1 is a composite supernova remnant featuring a shell structure and an inner Pulsar Wind Nebula. The shell is visible in the radio band, while Fermi has detected the radio-quiet pulsar PSR J0007+7303 at its core. Gamma-ray detectors such as LHAASO and VERITAS have detected TeV emission in the vicinity of the pulsar. However, the derived SEDs from LHAASO WCDA and VERITAS show significant discrepancies, which could be due to a complicated energy-dependent morphology not accounted for in the spectral analysis, and different angular resolution of the two experiments.
CTA 1 has been a target for dedicated observations by the SST-1M telescopes, a pair of small-sized Imaging Atmospheric Cherenkov Telescopes (IACTs) capable of operating in both mono and stereo modes. Located at the Ondřejov Observatory in Czechia, these telescopes are sensitive to the high energy range of the gamma-ray spectrum, spanning from 1 to 300 TeV. To investigate the very high-energy emission of CTA 1, the SST-1Ms have accumulated approximately 20 hours of observations, aiming to further constrain the characteristics of the source's high energy emission, and to shed some light into the discrepancy between different experiments.

Speaker: Bastien Lacave

16:35 Joint eROSITA and H.E.S.S. analysis of MSH 15-52 using Gammapy

Pulsar wind nebulae (PWNe) are prominent sources in the very-high energy (VHE) gamma-ray sky, constituting the most numerous identified source class in the H.E.S.S. Galactic Plane Survey (HGPS). They are comprised of energetic particles originating from the pulsar and expanding into the surrounding medium. As such, PWNe are of very high scientific interest as PeVatron candidates, objects that could potentially accelerate particles up to PeV energies. Additionally other aspects of their acceleration mechanism are being actively investigated, such as the open question of whether they accelerate not only leptonic but also hadronic particles, and the details of their morphology and particle transport mechanism.
As PWNe emit photons over a broad range of the electromagnetic spectrum, multiwavelength (MWL) studies are crucial for the investigation and study of their emission.
In this vein we present a joint eROSITA X-ray and H.E.S.S. gamma-ray study of the PWN MSH 15-52. We showcase our custom code for integrating the EDR and DR1 eROSITA data into the Gammapy framework, a python package optimised for the analysis of gamma-ray data. We present the first 3D (spatial and spectral) fit to eROSITA data by using Gammapy.
We furthermore combine these data with the public H.E.S.S. gamma-ray observations of MSH 15-52, resulting in a joint physical fit of the underlying particle population, and a subsequent discussion of the physical implications of our results.
Finally we give an outlook towards future efforts in MWL studies of PWNe and the broader context of MWL data analysis with Gammapy.

Speaker: Katharina Egg (Erlangen Centre for Astroparticle Physics (ECAP), Friedrich-Alexander-Universität Erlangen-Nürnberg)

15:20 → 16:50 OE

Convener: Anastasia Tezari (CERN)

15:20 Development of a Smartphone-Based Radiation Detection App and Its Application to Science Education Outreach – New Possibilities for Science Education Through a Cosmic Ray Detection App

Cosmic rays provide crucial insights into astrophysical phenomena and fundamental physics. However, their detection traditionally requires specialized, costly equipment, limiting accessibility for education. This study explores the potential of using commercially available smartphones and tablets equipped with CMOS image sensors for cosmic ray detection. We developed the “Soramame” app (https://soramame.n.kanagawa-u.ac.jp/en/), enabling users to detect cosmic rays by leveraging the charge generation properties of CMOS sensors when exposed to high-energy particles. This study evaluates the app’s reliability, educational impact, and potential for citizen science. CMOS image sensors, made of silicon semiconductors, detect electrical charges generated by charged particle interactions and convert them into digital images. “Soramame” visualizes cosmic ray events in real-time without specialized equipment, lowering barriers to participation in cosmic ray research. Its low-cost, accessible, and user-friendly design matches students, educators, and the general public. To assess its practicality, we conducted controlled experiments in various environments. The first experiment, conducted on commercial flights, demonstrated an increased cosmic ray flux at high altitudes compared to ground levels. The second experiment tested the app’s response to controlled radiation sources, confirming that the CMOS sensor effectively detects charged particle interactions. These results demonstrate that consumer-grade CMOS sensors can be repurposed for cosmic ray detection, offering a valuable tool for scientific and educational applications. Beyond its scientific capabilities, we examined educational applications. Traditional science education struggles to engage students with abstract concepts like astrophysics and radiation physics. “Soramame” enhances hands-on learning by allowing students to use their devices to detect and analyze cosmic rays. By making invisible cosmic interactions visible, students develop a deeper understanding of physical phenomena, fostering curiosity and engagement. The app supports inquiry-based learning, encouraging students to collect and analyze data under different conditions (e.g., altitude, shielding, time of day) and discuss findings.

Additionally, its data-sharing feature enables users worldwide to contribute and compare results, promoting collaborative learning and citizen science. This study also highlights the potential for a global cosmic ray observation network, where participants collect and share real-time data on cosmic ray flux. Such a network could provide valuable insights into cosmic ray variations while fostering public engagement in scientific research. Future improvements will focus on enhancing detection accuracy, expanding educational integration, and refining data processing capabilities. By incorporating “Soramame” into formal and informal education, we aim to bridge the gap between research and public understanding, advancing scientific literacy and encouraging broader engagement with astrophysics. Our findings demonstrate that a smartphone-based cosmic ray detection system can be a powerful tool for science education and outreach. The development of accessible, interactive scientific tools like “Soramame” has the potential to revolutionize STEM education by making complex physical phenomena more tangible. Through this initiative, we seek to inspire future scientists, expand citizen science in astrophysical research, and create new opportunities for interdisciplinary learning.

Speaker: Wakiko Takano (Kanagawa University Research Institute for Engineering)

15:35 “Cosmic SOS”: An adventure game at CERN Science Gateway

Detectors are essential tools for modern astroparticle physics. Found in ground-based and space-borne observatories, they are used to detect, analyse and monitor all types of electromagnetic and particle radiation. Following similar principles, cutting-edge detectors at CERN are used to detect the products of high-energy collisions, allowing scientists to confirm or disprove theoretical models about the fundamental laws of nature and the evolution of the universe.

Building on this parallel, a new activity has been developed at CERN Science Gateway, CERN’s new education and outreach center. This activity is designed for 13-15 y.o. students in the form of an adventure game. Participants embark on a journey as members of a spaceship crew tasked with deciphering a message coming from deep space. To succeed on their mission, they must solve a series of puzzles that allow them to explore electromagnetic and particle radiation.

For this activity, a range of detectors are employed, including the MiniPIX pixel detector, a radiation detector based on the Timepix silicon pixel technology, developed at CERN. These novel devices constitute powerful tools not only for scientific research but also for the communication of complex concepts about space and particle physics to students and the general audience. By allowing the participants to interact with these detectors first-hand and by highlighting their utilisation not only at experiments taking place at CERN, but also on the International Space Station (ISS) or on trips to the moon, they gain insight into the broader applications of detectors, which extend beyond the terrestrial laboratories to the frontiers of space exploration.

In this presentation, we will report on the initial conception and iterative development process of the adventure game, showcase its different activities and outline future directions.

Speaker: Panagiota Chatzidaki (Uppsala University (SE))

15:50 The Distributed Electronic Cosmic-ray Observatory (DECO)

The Distributed Electronic Cosmic-ray Observatory (DECO) is a project that enables users to detect cosmic rays and other ionizing radiation with their own cell phones. The DECO app treats cellphone cameras as silicon track detectors. Event images are uploaded to a web-based database where users and other members of the public can query, download, and analyze them. A convolutional neural network automatically classifies events by morphology for particle identification. DECO detects atmospheric muons through their ionization loss in camera image sensors. It also detects radioactive decay products, including electrons that undergo multiple Coulomb scattering and gamma rays that Compton scatter. Our GEANT-based detector Monte Carlo simulation produces images qualitatively and quantitatively similar to those of DECO experimental data. The simulation is well suited for training image classifiers based on machine learning and quantifying the performance of image classifiers and event reconstruction algorithms. DECO makes otherwise invisible particles and phenomena visible to members of the public using their own devices, applying the same concepts and technologies as professional particle physics detectors. We present an overview of the DECO project, which lies at the nexus of education, outreach, and research.

Speaker: Justin Vandenbroucke (University of Wisconsin – Madison)

16:05 CERN Science Gateway exhibitions.

CERN Science Gateway opened its doors to the public in autumn 2023. Part of this new education and outreach centre are the exhibitions that combine immersive scenography with interactive exhibits and real scientific objects.
Three exhibitions are available for the public. In Discover CERN visitors learn more about the accelerators and detectors at CERN. Our Universe consists of two parts: in Back to the Big Bang visitors travel back in time to beginning of our universe, in Exploring the Unknown they discover how artists were inspired by their interactions with scientists. And in Quantum World visitors experience the weird world of elementary particles.
The exhibitions are targeting a broad section of the public, both those with an existing interest in science and physics as well as those with no prior knowledge that are looking for a nice day out. This presentation will give an overview of the exhibitions as well as present results from both a visitor survey and observing visitors in the exhibitions.

Speaker: Tamara Caldas Cifuentes (Goethe University Frankfurt (DE))

16:20 Immersive experiences for gravitational wave outreach

The first detection of gravitational waves in 2015 and the birth of multimessenger astronomy with gravitational waves in 2017 represented a real revolution in the way we observe the cosmos. As communication office of EGO, the institution that hosts the Virgo gravitational wave detector, we are constantly looking for new ways to tell the public about these great milestones, in the most engaging and diverse ways possible, not just with words, spoken and written, but through their bodies and all of their senses.

The aim is to illustrate some concrete examples of this approach, but also to reflect on the actual impact of these installations and their effectiveness in contributing to convey scientific content and arouse interest, for example, in some aspects of astroparticle physics. Some immersive interactive experiences, used in the outreach of EGO and Virgo are the following.

Big Bang Machine
The Van 'Big Bang Machine' is a mobile immersive installation, curated by the European Gravitational Observatory (EGO) with the support of the Pisa Foundation, IVECO and the European Union project AHEAD 2020, which takes visitors on a virtual journey through space and time to the origin of our Universe. As if on a science-fiction spacecraft, people of all ages travel back in time and discover the most violent phenomena of our Universe: gigantic black holes, mergers of stars denser than any matter imaginable, all the way back to the very first moments of the Cosmos, where the constituents of matter were generated. The van has toured to several cities in Italy, during festivals and other events, and will also travel abroad.

Space-time Installation
Einstein has shown that mass and energy deform space and alter time. For example, in the cosmos, violent collisions of massive bodies are able to generate ripples, which propagate through the fabric of space-time: gravitational waves. In the “Space-Time” installation, developed by INFN and EGO, visitors move around a room and experience how their body and movements can deform and warp space-time, as if they were a star, a supernova or a black hole.

Projections on the walls simulate the fabric of space-time, and through sensors the user’s presence and movements are shown visually in the projection as deformations of this structure. The installation has been included in several exhibitions all over Italy and abroad and it is permanently installed in a room at EGO for all visitors to see.

Black Hole Installation
The “Black Hole” installation, developed in collaboration with INFN, Fondazione Horcynus Orca and Fondazione Messina,encourages the visitor to play with the nature of black holes, and what would happen to our bodies in the proximity of one. Through stunning visuals and original sounds you can see your body’s energy get eaten by a black hole, or escape just in time outside of the event horizon. The installation is quite recent, and it debuted in 2023 at “Città della Scienza” in Naples, with great success among people of all ages and backgrounds.

Speaker: vincenzo napolano (European Gravitational Observatory - EGO - Italy)

16:35 Socioeconomic Impact of the Pierre Auger Observatory

The Pierre Auger Observatory has been operating in Malargüe, Province of Mendoza, western Argentina, for over two decades, significantly advancing our understanding of cosmic rays. Beyond its scientific mission, the installation and operation of the observatory has had profound social, economic, educational and cultural impact on the local community, the region and worldwide.

More than 90% of the observatory's annual operational budget is invested in the region, benefiting sectors such as tourism, hospitality, gastronomy, and local commerce. Additionally, the presence of international visitors and collaborations has fostered a rich
cultural exchange. Malargüe has emerged as a destination for scientific tourism, with the observatory as a major attraction, having welcomed over 178,000 visitors since its inauguration and boosting the region's development.

This talk will explore the broad direct and indirect benefits of the Auger Observatory and the key lessons learned from this endeavour. A new International Agreement signed in 2024 ensures the project's continuity for at least another decade, until 2035, reaffirming its scientific, economic, and social relevance.

Speaker: Dr Ingomar Allekotte (Comisión Nacional de Energía Atómica (AR), Instituto Balseiro)

15:20 → 16:50 SH: energetic events

15:20 On the effect of turbulence on large-scale drifts of solar energetic particles

The propagation of the Solar Energetic Particles (SEPs) in the heliosphere is guided by the large-scale Parker spiral magnetic field. The gradient and the curvature of the magnetic field give rise to drift of the particles’ guiding centres in the direction perpendicular to the magnetic field, leading the SEPs to gradually move away from their initial Parker spiral field lines. SEP propagation is also affected by solar wind turbulence, which scatters particles in pitch angle and spreads them across the average magnetic field due to field line meandering. It has been suggested that turbulence reduces the gradient and curvature drifts associated to the Parker spiral, however it is unclear to what extent they are reduced. We use our new analytic heliospheric turbulence model (Laitinen et al, ApJ 143,908 (2023)) to investigate the magnitude of drift reduction for particles injected close to the Sun. The turbulence model reproduces the dominant feature of plasma turbulence in the heliosphere, with the transverse 2D component having both wave and magnetic field vectors normal to the Parker spiral magnetic field: such a model provides an ideal tool to improve our understanding of turbulent drift reduction. We use full-orbit test particle simulations of 10, 100 and 1000 MeV protons within the modelled heliospheric turbulence, and present a method to evaluate their drift in the spatially-evolving heliospheric configuration. We assess the reduction of the drifts by turbulence by comparing the heliospheric turbulence simulations with a configuration without turbulence. Our findings show that the drifts are reduced by a factor 0.2-0.9 compared to a turbulence-free heliospheric configuration, varying as a function of proton energy and relative turbulence amplitude. The values obtained differ from theoretically predicted estimates particularly at low proton energies and indicate considerably weaker reduction of drift due to turbulence than previously assumed. Our results suggest that the guiding centre drifts remain a significant factor for the SEP intensity evolution in the heliosphere.

Speaker: Timo Laitinen (University of Central Lancashire, UK)

15:35 Solar event of May 11, 2024 some conclusions on the behavior of cosmic rays

On May 11 2024 a train of at least three magnetic cloud connected to fast coronal mass ejections impacted Earth during a very short period of less than 24 hours. In this so complicated solar wind conditions around Earth, a ground level enhancement was observed by neutron monitors the same 11 May at 2 AM just in between of the first magnetic cloud and the second one. In this time, to twins detectors with the capabilities of measuring neutron and muon fluxes and muon incoming directions, located at Livingston Island (Antartica) and Tenerife Island (Spain) respectively, observed this complex event as a deep and wide Forbush decrease including a ground level enhancement weak signature in the detector at Livingston Island. A complete study of the solar wind conditions including the measurements of both detectors is presented in this work. Conclusions about cosmic ray spectrum variations and local and temporal cosmic ray anisotropies are inferred from the unique data of these detectors.

Speaker: Prof. Juan José Blanco Ávalos (University of Alcala)

15:50 In-depth analysis of selected major solar events with the HEPP-L particle detector onboard CSES-01 in low-Earth orbit

The characterization of the effects of solar disturbances on the Earth's ionosphere is crucial for the monitoring and understanding of space weather. While satellites orbiting outside of the Van Allen belts allow for direct measurements of the ejected particles and of magnetic field perturbations, low Earth orbit spacecraft, such as the China Seismo-Electromagnetic Satellite (CSES-01), provide a direct assessment of the effect of these events on the Earth ionosphere. Here we present a detailed study of proton flux perturbations measured by the High-Energy Particle Package (HEPP-L) onboard CSES-01 during four major, prototypical solar events: the ground-level enhancement (GLE) of 2021-10-28; the X3.3 flare of 2023-02-09; the GLE of 2024-05-11; the GLE of 2024-06-08. The analysis of fluxes measured by HEPP-L, capable of detecting 2 MeV-20 MeV protons, relies on a robust statistical approach to model the expected background flux in ordinary conditions and identify anomalies attributable to space weather events. For the case studies outlined above, upon identification of anomalies, we assess the properties of the excess proton flux, including the temporal evolution of its spectral features. These results enrich the present knowledge of the effects of solar activity on the Earth's ionosphere, demonstrating the crucial role that CSES-01, and the forthcoming CSES-02, can play in space weather studies.

Speaker: Alessio Perinelli (University of Trento)

16:05 Are extreme solar particle events and superflares related? A probabilistic view

Solar eruptive activity has many forms, the most important and well-studied are solar flares, coronal mass ejections, and solar energetic particle (SEP) events. It is mostly unknown what is the upper limit for the intensity of different eruptive activity events. For now, only traces of extreme solar particle events (ESPEs) were discovered in cosmogenic isotope data in datable natural archives, while extreme solar flares and CMEs were not registered and it is not clear if Sun is capable of producing it. Only several ESPEs were found in cosmogenic isotope data for the Holocene period which makes their frequency roughly 1/1500 years. At the same time, astronomical observation by Kepler satellite recently uncovered superflares on solar-like stars, which are orders of magnitude more intense than ones registered on the Sun. A new reanalysis of Kepler data gives quite a high frequency of these events − up to 1/100 years for flares with bolometric energy more than >1034 erg. The observed occurrence rate of ESPEs produced by Sun and super-flares on solar like stars is biased. In our talk, we are showing that the difference in occurrence rates between extreme eruptive events is natural and caused by the probabilistic nature of eruptive events. For that, we are using the systematic observations made by the GOES satellite series and data from a ground-based network of neutron monitors. Then we are studying in detail the conditional probability of observing SEP events given the registration of solar flare − as a function of both SEP and flare intensity. In the end, we propose an analytical model, that agrees well with direct XRS and SEP observations, as well as predicts the observable rate of ESPEs. Within the model, The occurrence of ESPE does not necessarily require a super-flare as the source, and strong butt not extreme (>X10 class) flares can potentially lead to an ESPE under a very favourable conditions.

Speaker: Sergey Koldobskiy (University of Oulu)

16:20 Ion-rich acceleration during an eruptive flux rope event in a multiple null-point configuration

We report on the sources of gamma-ray emission above 100 MeV in the very impulsive GOES M3.3 class flare SOL2012-06-03. The >100 MeV emission during the prompt phase displayed a double-peaked temporal structure, with the highest peak occurring 17$\pm$2 seconds after the first peak with a difference in flux of almost a factor of 3. The HXR and gamma-ray time profiles during the impulsive phase seem to indicate two separate acceleration mechanisms at work. The first appears to be flare-related, with the HXR and gamma-ray peaks coinciding in time and shape, whereas the second gamma-ray peak has no visible HXR or radio counterpart. This behavior suggests a potentially pure ion acceleration mechanism. AIA imaging shows a bright elliptical ribbon and a transient brightening in a region on the north-western (NW) side of the ribbon. An erupting flux rope, visible in all the AIA EUV filters seconds prior to the start of the second gamma-ray peak, is found to propagate towards the NW direction and a coronal wave is also observed in association with this event. This global wave also has fastest expansion towards the NW. The time profile of the 94 and 335 A intensity of the NW region shows that the fastest increase coincides with the time that the second gamma-ray peak reaches its maximum value, indicating a coupling between the two. Nonlinear force-free extrapolations at the time of the impulsive peaks show closed loops connecting the NW region to the south-eastern part of the elliptical flare ribbon and the magnetic topology of the region revealed clusters of nulls running along the western edge of the flaring region towards the NW transient brightening. These observations suggest a spine-and-fan geometry, and based on these observations we interpret the second gamma-ray peak as being due to null-point reconnection accelerating predominately ions to relativistic energies. The >100 MeV emission from this flare also exhibits a delayed phase with an exponential decay of roughly 350 seconds. We find that the delayed emission is consistent with ions being trapped in a closed flux tube with gradual escape via their loss cone to the chromosphere.

Speaker: Melissa Pesce-Rollins

16:35 Solar Energetic Electron Events with a Spectral Bump Break

The energy spectrum of solar energetic electron (SEE) events carries crucial information on the origin/acceleration at the Sun. We present ten solar energetic electron (SEE) events measured by Wind/3DP at ~1 to 200 keV with a bump break in the electron peak flux vs. energy spectrum. We assume that these bump SEE events consist of two electron populations: primary population (described by the pan-spectrum (PS) function) and bump population (described by the Gaussian function) that dominate at low and high energies, respectively. We construct two formulae to fit the SEE energy spectrum by multiplying a PS function with a natural exponential form of Gaussian function (i.e., the MUL formula) and by adding a PS function with a Gaussian function (i.e., the ADD formula). The fitting results suggest that the MUL fitting reflect the physics nature in the formation process. For the primary electron population, the MUL fitting obtains an upward-bending double-power-law spectrum for the #10 event with a spectral index of 3.85 (1.74) at energies below (above) ~4.6 keV, and a single-power-law spectrum for the other nine events with a median spectral index of 2.52. For the bump electron population, the fitted center energy has a median value of 59 keV. For the events associated with SXR flares (west-limb CMEs), the flare class (CME angular width) shows a positive correlation with the estimated electron number of power-law population Npl and of number ratio Nbp/Npl at 10-400 keV. These results indicate that for these bump SEE events, the power-law electron population can be produced by some flare-related processes that occur high in the corona, while the bump population can be accelerated by some CME-related processes acting on the power-law population. The bump-like spectrum might also be the intermediate spectrum during the evolution from single-power-law to downward-bending double-power-law.

Speaker: Linghua Wang (Peking University)

16:50 → 17:05 Break

17:05 → 18:21 CRD: acceleration

17:05 How Cosmic Rays Reshape Their Accelerators

Charged particles accelerated at the forward shocks of supernova remnants (SNRs) likely constitute the majority of the Galactic Cosmic Ray (CR) population. They also play a vital role in regulating the hydrodynamical evolution of their accelerators. For example, efficient CR acceleration at shocks leads to enhanced compression, which in turn alters the distribution of CRs released into the Galaxy. Galactic CRs can also extend the lives of SNRs, serving as a non-thermal pressure reservoir that supports expansion after the onset of the so-called “radiative phase,” when thermal gas pressure is lost to atomic transitions. In this talk, I will explore the dynamical role of CRs in regulating SNR evolution, and introduce observational evidence for CRs modifying the hydrodynamics of their accelerators. In particular, by coupling magnetohydrodynamic simulations of SNR evolution with a self-consistent model of CR acceleration at shocks, I will show how the presence of CRs and magnetic fields (which are themselves amplified by CRs) can drastically alter the both the radio and $\gamma$-ray appearance of a radiative SNR. As I will demonstrate, proper accounting for the dynamical effects of both CRs and magnetic fields is essential to producing simulated SNRs that are consistent with multi-wavelength observations.

Speaker: Rebecca Diesing (Institute for Advanced Study and Columbia University)

17:20 On the Non-universality of Diffusive Shock Acceleration

Diffusive Shock Acceleration (DSA) is a prominent way of producing high-energy particles; one of its most appealing features is that it is expected to return power-law spectra, with a slope that only depends on the shock compression ratio.
I summarize how first-principles plasma simulations have shown that self-generated magnetic turbulence is crucial in controlling such a slope, too, and discuss how this reconciles observations of supernova remnants and radio relics in galaxy clusters.

Speaker: Damiano Caprioli

17:35 Breaking the universal power law: Advanced models of diffusive shock acceleration in Galactic sources

Diffusive shock acceleration (DSA) is a promising acceleration process in a hierarchy of sources, reaching from stellar termination to Galaxy cluster shocks.
Two of the relevant parameters defining the maximal energy reached at the accelerator are the turbulent magnetic field and the shock's lifetime. In this contribution, we show how time-dependent models in complex geometries and diffusion descriptions beyond a simple scaling in energy, taking structured turbulence and non-linear feedback of the CRs into account, lead to deviations from the universal $E^{-2}$ power law at a strong shock.

By modeling shocks in the Galactic halo, we show how time-dependent transport gives rise to harder energy spectra and the collision of shocks can lead to an enhancement at high energies. The influence of energy-dependent escape including adiabatic cooling on the spectrum is discussed. When drifts of the CRs due to self-induced turbulence are taken into account, e.g. spectra at supernova remnants can deviate from $E^{-2}$ matching observations. Harder energy spectra can also be obtained when superdiffusion is considered, which might result from structured turbulence close to astrophysical sources.

All modeling is done in a single framework, a modified version of CRPropa 3.2 based on the integration of stochastic differential equations.

Speaker: Sophie Aerdker (Ruhr University Bochum, RAPP Center)

17:50 Particle acceleration in neutron star ultra-strong magnetic fields

In this presentation, we focus on the particle acceleration efficiency and radiation reaction damping in strongly magnetized fields with realistic field strengths of $10^5$ T to $10^{10}$ T, typical of millisecond pulsars, young pulsars and magnetars. Different particle pushers have been implemented, from an exact analytical solution including radiation reaction in the Landau-Lifshitz approximation to the more simple prescription of the radiation reaction limit (Aristotelian dynamics).

We investigated particle acceleration and the impact of radiation reaction for electrons, protons and iron nuclei plunged around millisecond pulsars, young pulsars and magnetars, comparing it to situations without radiation reaction.

We found that the maximum Lorentz factor depends on the particle species but only weakly on the neutron star type. Electrons reach energies up to $\gamma_e \approx {10^8}-{10^9}$ whereas protons energies up to $\gamma_p \approx 10^5-10^6$ and iron up to $\gamma \approx 10^4-10^5$. While protons and irons are not affected by radiation reaction, electrons are drastically decelerated, reducing their maximum Lorentz factor by 2 orders of magnitude. We also found that the radiation reaction limit trajectories fairly agree with the reduced Landau-Lifshitz approximation in almost all cases.

Speaker: Jérôme Pétri

18:05 Lightning in Cosmic Ray Sources Shapes Their Spectra

The Loaded Layer-Cake Model provides a quantitative framework for understanding cosmic ray spectra through time-dependent acceleration, diffusion, and spallation processes within SN-shocks, wind shock shells, and OB-Superbubble regions. After integration, the model yields a series of mathematical expressions, which are applied to observational AMS cosmic ray data to provide fits. In the interaction zone, a Kolmogorov spectrum of magnetic field irregularities shapes the rigidity-dependent variation in cosmic ray spectra, resulting in a local spectral slope change of −1/3. In the bubble zone, lightning-induced magnetic wave-fields excited by electric discharges influence the spectra, leading to a slope change of −5/3. Additionally, at rigidities greater than 135 GV, a global fit shows a common spectral slope of −2.65, depicting behavior of the acceleration zone. The model accommodates AMS data for primary cosmic rays (He, C, O, Fe) and secondary cosmic rays (Li, Be, B, ³He) and has been expanded to include Ne, Mg, Si, N, Na, Al, and F. Fit coefficients provide a foundation for comprehending cosmic ray behavior throughout the entire spectrum of each element. Fitting results for the expanded dataset are presented, and convincingly demonstrate that the spectral slopes accurately reflect the variations induced. Challenges with the current model are analyzed and discussed. Future refinements are proposed to enhance the model’s accuracy and capability in understanding cosmic ray propagation and interactions.

Speaker: Sasa Maricic

17:05 → 18:35 CRI: mass composition

17:05 Measurement and Interpretation of UHECR Mass Composition at the Pierre Auger Observatory

The Pierre Auger Observatory has driven the field of ultra-high-energy cosmic ray (UHECR) physics, producing several groundbreaking observations over the last 20 years. One of the most striking findings has been the complex evolution of UHECR mass composition, as revealed by detailed analyses of observables such as the depth of shower maximum (Xmax) and the muon content of showers. As more data are collected and sophisticated analyses are undertaken, not only are new fine details emerging, but the general picture of UHECR mass composition is becoming increasingly robust. This contribution will present recent results on UHECR mass composition derived from surface, fluorescence, and radio detectors. Together with other key findings from the Observatory, these results converge to present a coherent picture of UHECR mass composition- effectively ruling out proton dominance and challenging the interpretation of the observed flux suppression near 46 EeV as a purely proton-induced GZK effect. To finish the contribution, we discuss how the upgraded detectors in the Observatory’s second phase of data-taking will further refine our understanding of UHECR mass composition.

Speaker: Prof. Eric Mayotte (Colorado School of Mines)

17:20 Hybrid Measurement of UHECR Mass Composition with TAx4

We present an analysis of ultra-high energy cosmic ray (UHECR) mass composition based on four years of data collected by Telescope Array’s expansion project, TA×4. Reconstructing events in hybrid mode, combining information from both the fluorescence detectors (FDs) and surface detectors (SDs), we measure the mass composition of UHECRs using the distribution of the depth of air shower maxima (Xmax). The hybrid technique enhances the precision of the reconstructed shower geometry, leading to more accurate Xmax measurements. Our results suggest a predominantly light composition, with protons and light nuclei comprising the majority of cosmic rays above 10^18.5 eV.

Speaker: Zane Gerber (University of Utah)

17:35 Probing the mass composition of TeV cosmic rays with HAWC

In this contribution, we have investigated the energy spectra of the elemental mass groups of cosmic rays for the Light (H+He), medium (C+O) and heavy (Ne-Fe) components using the HAWC observatory. The study was carried out in the energy interval from 10 TeV to 1 PeV using almost 5 years of data on hadronic air showers. The energy spectra were unfolded using the bidimensional distribution of the lateral shower age versus the reconstructed primary energy. We have employed the QGSJET-II-04 high-energy hadronic interaction model for the current analysis. The results show the presence of fine structure in the spectra of the light, medium and heavy mass groups of cosmic rays.

Speaker: Dr Juan Carlos Arteaga-Velazquez

17:50 Constraints on the spread of nuclear masses in ultra-high-energy cosmic rays based on the Phase I hybrid data from the Pierre Auger Observatory

We present an analysis of the correlation between the depth of the maximum of air-shower profiles and the signal in water-Cherenkov stations in events simultaneously recorded by the fluorescence and surface detectors of the Pierre Auger Observatory. The analysis allows constraints to be placed on the spread of nuclear masses in ultra-high-energy cosmic rays with a minor impact from the experimental systematic uncertainties and uncertainties in air-shower simulations. Due to this unique feature, the correlation analysis has previously allowed us to exclude all pure and proton-helium compositions near the ankle in the cosmic-ray energy spectrum at 5 sigma confidence level. The same property makes the correlation analysis an effective tool for testing the consistency of predictions of the post-LHC hadronic interaction models, including their latest versions such as EPOS LHC-R, QGSJet-III-01, Sibyll^star and Sibyll 2.3e. In this work, the correlation analysis using the Phase I hybrid data from the Pierre Auger Observatory is presented. The analysis uses the latest generation of hadronic models and covers an extended energy range around the ankle in the cosmic-ray spectrum.

Speaker: Dr Alexey Yushkov (Institute of Physics AS CR, Prague)

18:05 Measurements of the variance of the logarithmic mass of cosmic rays from 0.3 to 30 PeV with LHAASO-KM2A

We introduced a parameterization method to analyze the mean muon content $<\ln N_{\mu}>$ and its dispersion $\sigma^{2}(\ln N_{\mu})$ in relation to the mass composition of cosmic-rays. This approach enhances the Heitler model for air showers by employing a parameterization that incorporates the first two moments of the logarithmic mass distribution $\ln A$ and $\sigma^{2}_{\ln A}$. This method was tested through simulations with various mass distributions, demonstrating its applicability. We applied this method to data from LHAASO-KM2A, using three hadronic interaction models: QGSJET-II-04, EPOS-LHC, and SIBYLL 2.3d, for energies ranging from 0.3 to 30 PeV, thereby extracting the first two moments of the logarithmic mass distribution. Despite differences among these models, the results showed a consistent trend: as energy increases, $\sigma^{2}_{\ln A}$ decreases to a minimum at the knee region, then rises with further increases in energy. This method not only deepens our understanding of average mass but also elucidates the dynamics of mass dispersion. Additionally, it serves to validate the effectiveness of hadronic interaction models and aids in refining future models.

Speaker: Xiaoting Feng (Shandong University)

18:20 Study of cosmic ray spectrum and composition by using coincident events between LHAASO and ENDA

The cosmic ray energy spectrum has always been an important tool for investigating fundamental issues related to origin of cosmic rays. The so-called ”knee” around ∼4 PeV, at where the spectral index changes from-2.7 to-3.1, were observed by several experiments. The measurements of the ”knee” by the ground based experiments still have deviations. Most ground-based experiments measure the second particles such as the electromagnetic component and muons in Extensive Air Showers (EAS) to reconstruct the messages of primary cosmic rays, so as Large High Altitude Air Shower Observatory (LHAASO). Electron-Neutron Detector Array (ENDA) was added to measure thermal secondary neutrons generated by high energy hadrons of EAS in conjunction with LHAASO, thereby enhancing the ability to discriminate the mass composition of the primary cosmic rays as well as to understand a stage of the EAS longitudinal development.
In 2023, ENDA was expanded from 16 to 64 detectors so called ENDA-64 in area of 1000 m^2 to measure cosmic rays from 400 TeV to 20 PeV. Coincident events between ENDA-64 and LHAASO are analyzed carefully. In one or two years, we can obtain high statistics of data for studying energy spectrum of light components (H and He) because their hadrons reach observation level at lower energy due to higher energy per nucleon. Hybrid detection by using LHAASO and ENDA can provide a full secondary particle measurement of EAS including electrons, muons, atmospheric Cherenkov light and hadrons which are the main EAS component. In this report, method of data analysis including calibration, data quality check, reconstruction, energy determination and composition separation is described, and results by using full secondary particles are presented.

Speaker: Prof. shuwang cui (HEBEI NORMAL UNIVERSITY)

17:05 → 18:35 DM: indirect detection

17:05 Discovering the Higgsino at CTAO-North within the Decade

Higgsino dark matter (DM) is a well-motivated candidate in supersymmetric theories, with a 1.1 TeV thermal higgsino naturally accounting for the observed DM abundance. Despite its strong theoretical foundation, detecting the higgsino remains challenging.

Direct detection is hindered by its suppressed scattering cross-section and theoretical uncertainties on contaminated background, complicating signal discrimination. Collider searches require extremely high-energy facilities, such as a 100 TeV hadron collider or a 10 TeV muon collider, due to the higgsino’s weak coupling and high mass. Given these challenges, alternative detection strategies—particularly indirect searches via high-energy astrophysical observations—are crucial.

The Cherenkov Telescope Array Observatory (CTAO), with CTAO-North in La Palma, Spain, and CTAO-South in Atacama, Chile, offers a promising indirect detection approach by probing gamma rays from potential DM annihilation, particularly in the Galactic Center. CTAO-North has achieved the first light with its first Large-Sized Telescope (LST), while CTAO-South, expected to be fully operational in the 2030s, will observe the Galactic Center under optimal conditions. Alternatively, CTAO-North can observe the Galactic Center at so-called large zenith angles —tracking the Galactic Center along the horizon— enhancing sensitivity at TeV energies at the cost of a higher energy threshold. With this observation mode, we regard that CTAO-North is capable of complementing the CTAO-South view.

Using CTAO simulations of instrument responses, this study projects sensitivity of higgsino searches with CTAO-North and CTAO-South under a realistic observational timeline. In particular, considering the phased construction, we assume a two-stage telescope configuration for CTAO-North: the LST sub-array and the planned full array. Notably, our projections indicate that CTAO-North could achive the required sensitivity within the next decade, reinforcing gamma-ray observations as a viable method for higgsino DM detection. The findings and their implications are presented in this contribution.

Speaker: Tomohiro Inada (Kyushu University (JP))

17:20 Search for line-like and box-like features in Galactic gamma-ray spectra as signatures of dark matter using 15+ years of Fermi-LAT data

Dark Matter (DM) particles may either self-annihilate or decay, producing detectable Standard Model (SM) particles, including gamma rays. These processes could lead to excesses in the gamma-ray energy spectra observed on Earth. In this work, we search for those excesses using the Fermi Large Area Telescope (Fermi-LAT) observations of the Milky Way in an energy range from 1 GeV to 1 TeV. We developed a maximum likelihood fit procedure with sliding energy windows to search for line-like features (smoking gun signals) as indirect signature of DM self-annihilation and decay processes that directly produce gamma rays. Our analysis is based on 185 months (15+ years) of Fermi-LAT data in which we selected five regions of the sky (RoIs) to optimize sensitivity for different theoretically motivated DM scenarios using a combined likelihood analysis technique. We also accounted for systematic uncertainties using the Galactic Plane as a control region.
Additionally, we investigate the presence of potential box-shaped spectral features in the gamma-ray spectra, which could result in a scenario in which DM annihilation or decay involves long-lived mediators that decay into final states of gamma rays detectable on Earth.
In both scenarios considered in this work, we do not find any significant detections, so we set more stringent upper limits for the DM velocity-averaged annihilation cross section compared to those quoted in literature.

Speaker: Mario Giliberti (Dipartimento Interateneo di Fisica dell'Università e Politecnico di Bari)

17:35 A Joint Gamma-ray Search for Dark Matter in Dwarf Spheroidal Galaxies with Fermi-LAT, HAWC, H.E.S.S., MAGIC and VERITAS

Weakly Interacting Massive Particles (WIMPs) in the GeV-TeV mass range could produce gamma rays through self-annihilation, offering potential observational signatures for indirect dark matter (DM) searches. Dwarf spheroidal galaxies (dSphs) of the Milky Way are prime targets for such studies due to their high inferred DM-induced gamma-ray fluxes and minimal astrophysical background.

In this contribution, we present the final results of the first combined constraints on DM annihilation in dSphs obtained using data from five leading gamma-ray observatories: the space-based Fermi-LAT (100 MeV-100 GeV), the ground-based H.E.S.S., MAGIC, and VERITAS (100 GeV-10 TeV), and the water Cherenkov detector HAWC (>10 TeV).

Each experiment analyzed its respective dataset using a coordinated statistical approach, ensuring a consistent treatment of systematics and background estimation. The individual results were then combined in a joint likelihood analysis, significantly improving sensitivity to potential DM signals.

By integrating these independent datasets, we derive stringent upper limits on the velocity-weighted annihilation cross-section $\langle\sigma v\rangle$ over a broad DM mass range of 5 GeV to 100 TeV. The obtained constraints improve with respect to the individual searches by a factor of 2-3, depending on the DM mass and annihilation channel. For instance, the observed 95% confidence level upper limits on $\langle\sigma v\rangle$ for a 2 TeV dark matter particle annihilating into $\tau^+\tau^-$ pairs range between $1.5 \times 10^{-24}$ cm$^3$ s$^{-1}$ and 3.2 × 10$^{-25}$ cm$^3$ s$^{-1}$ depending on the assumed dark matter distributions.

These results set some of the most stringent constraints on DM annihilation in dSphs to date, showcasing the power of multi-instrument synergy. Our findings underscore the critical role of cross-collaboration among gamma-ray observatories and establish a methodological framework for future analyses, including those incorporating next-generation gamma-ray and neutrino telescopes.

Speaker: Javier Rico (Institut de Física d'Altes Energies (IFAE))

17:50 Prospects for the detection of Dark Matter with Long-lived Mediators in the Sun using the Southern Wide-field Gamma-ray Observatory

The search for dark matter is advancing into a new era with the development of next-generation gamma-ray observatories, which will significantly enhance detection capabilities. These instruments will extend the limits of detection, offering new opportunities to investigate one of the most elusive components of the universe. Among them, the Southern Wide-field Gamma-ray Observatory, SWGO, stands out for its potential to detect gamma-ray signals originating from dark matter particles trapped within the Sun. This work focuses on hidden sector models, particularly secluded scenarios, where dark matter particles annihilate into long-lived mediators. Unlike standard annihilation channels occurring deep within the Sun’s core, in these scenarios, dark matter annihilates into these mediators that escape the dense solar environment before decaying into detectable gamma rays. The detection of these decay products by SWGO could provide valuable insights into dark matter interactions. Our analysis indicates that SWGO will reach a high level of sensitivity, probing spin-dependent cross-sections as low as 10⁻⁴⁶ cm² for dark matter masses below 5 TeV. This represents a substantial improvement over current detection capabilities, improving current indirect detection constraints by over an order of magnitude. Such advancements will not only strengthen the search for dark matter but also contribute to a deeper understanding of its fundamental properties.

Speaker: Micael Andrade (São Carlos Institute of Physics - IFSC/USP)

18:05 Search for interactions of dark matter with high-energy neutrinos from extragalactic sources using the IceCube Neutrino Observatory

The recent observation of neutrino signals from extragalactic sources, TXS 0506+056 and NGC 1068, provide opportunities for searching for rare neutrino interactions. One scenario of interest is the interaction between neutrinos and dark matter (DM). Assuming dark matter is a new elementary particle described by the extensions of the Standard Model of particle physics (SM), a direct interface between SM particles and DM particles can exist. From these interactions with DM, the flux of high-energy neutrinos from extragalactic sources could be suppressed at specific energy ranges leading to a distortion of the neutrino spectrum. For a certain range of dark matter parameters, distorted neutrino spectra can be measured on Earth with large neutrino telescopes such as the IceCube Neutrino Telescope. An analysis has been performed to search for interactions of high-energy neutrinos from the IceCube-identified astrophysical neutrino sources with the DM in sub-GeV masses. Two benchmark interaction models assuming different mediators are introduced, and 10.4 years of the through-going track-like neutrino events from the Northern Sky are used. This contribution presents the first experimental search results for the interaction of DM and high-energy neutrinos from distant sources.

Speaker: Woosik Kang (Sungkyunkwan University)

18:20 Dark Matter from the Littlest Galaxies: Gamma-ray Insights from Ultra-Faint Dwarfs and IMBHs

Dwarf galaxies offer a unique window into the dark sector---either by being overwhelmingly dominated by dark matter or by having evolved in near isolation from disruptive baryonic processes. Using more than 15 years of Fermi-LAT gamma-ray data, we probe dark matter annihilation in two regimes. First, we target ultra-faint dwarf galaxies, such as the newly discovered Ursa Major III, whose extreme dark matter fractions make them ideal for indirect detection. Second, we search for boosted annihilation signals from dark matter spikes around IMBHs in dwarf galaxies. Although no significant gamma-ray excess is observed, our stringent upper limits challenge the standard thermal WIMP scenario up to multi-TeV masses. These results highlight that dwarf galaxies are among the strongest probes of dark matter, paving the way for future multi-messenger studies.

Speaker: Milena Crnogorcevic

17:05 → 18:20 GA: AGNs

17:05 Revisiting the flaring activity in early 2015 of BL Lac object S5 0716+714

We analyzed multiwavelength data of the BL Lac object S5 0716+714 to investigate its emission mechanisms during a flaring state observed in early 2015. We examined the temporal behavior and broadband spectral energy distributions (SEDs) during the flare. The size of the $\gamma$-ray emission region was estimated based on the variability timescale. To explore the multiwavelength properties of S5 0716+714, we employed three one-zone models: the synchrotron self-Compton (SSC) model, the SSC plus external Compton (EC) model, and the SSC plus pp interactions model, to reproduce the SEDs. Our findings indicate that, while the SSC model can describe the SEDs, it requires an extreme Doppler factor. In contrast, the SSC plus EC model successfully fits the SEDs under the assumption of weak external photon fields but requires a high Doppler factor. Additionally, the SSC plus pp interactions model also reproduces the SEDs, with $\gamma$-ray emission originating from $\pi^{0}$ decay. However, this model leads to a jet power that exceeds the Eddington luminosity, which remains plausible due to the flaring state or the presence of a highly collimated jet.

Speaker: Dr Hubing Xiao (Shanghai Normal University)

17:20 Recent observations of PKS 2155-304 with MAGIC and LST-1 in a multi-wavelength context

PKS 2155-304 is a well-known high-frequency peaked BL Lac (HBL) at redshift z=0.116, which has been extensively studied across the electromagnetic spectrum due to its rapid and large-amplitude variability. Several violent outbursts in X-rays and gamma rays have been observed in the past, with intra-night variability in very-high-energy gamma rays (VHE; E > 100 GeV) detected down to the minute timescale. The alternation of quiescent and enhanced states, observed with a tentative quasi-periodicity of 1.74 ± 0.13 years in high-energy (HE; 100 MeV < E < 100 GeV) gamma rays, makes this source a key target also for ground based gamma-ray instruments and in particular for the Imaging Atmospheric Cherenkov Telescopes. Its brightness, proximity, and well-determined redshift make this gamma-ray source a prime target for fundamental physics studies, including Lorentz Invariance Violation constraints, searches for axion-like particles, and studies of absorption on the extragalactic background light.

In the last two years, PKS 2155-304 has been independently monitored by the Major Atmospheric Gamma-ray Imaging Cherenkov (MAGIC) telescopes and the first Large-Sized Telescope (LST-1) of the Cherenkov Telescope Array Observatory located at the Roque de Los Muchachos Observatory (La Palma, Spain). The observations were carried out at large zenith angles (LZA; ZA > 55°) and the VHE data have been complemented by simultaneous observations in HE gamma rays (Fermi-LAT), X-rays (Swift-XRT) and optical wavelengths (ASAS-SN).

In this contribution, we present the long-term behaviour and discuss the emission mechanisms of PKS 2155-304. By integrating data from different instruments, we characterize the spectral energy distribution of the source and explore correlations between wavebands, thereby constraining particle acceleration mechanisms in blazar jets.

The analysis characterises the VHE gamma-ray spectral properties of PKS 2155-304, while the multi-wavelength comparisons reveal key trends in the activity of the source. These results lay the groundwork for future studies with next-generation Cherenkov telescopes.

Speaker: Lisa Nikolić (University of Siena & INFN Pisa)

17:35 Multi-wavelength analysis of NVSS J073326+515355

NVSS J073326+51535 is an extreme high-frequency-peaked BL Lac (EHBL) object located at redshift 0.065. It was discovered at very-high-energy (VHE; E > 100 GeV) by the MAGIC collaboration in 2018. We announce the VHE detection of NVSS J073326+51535 by the VERITAS collaboration and present a multi-wavelength study of this EHBL. These recent observations aim to further constrain the emission mechanisms for this class of objects.

Speaker: Juan Escudero Pedrosa

17:50 One Code to Fit Them All: Forward-Folding AGN Spectra Over 11 Energy Decades with Gammapy

Most modern studies of Active Galactic Nuclei (AGN) rely on broadband spectral analyses to constrain the plethora of particle acceleration and emission processes. Traditional analysis methods are often hindered by the use of proprietary tools tailored for each participating instrument, making it challenging to integrate multi-wavelength data in a consistent, reproducible[,,] and statistically correct way.

In this work, we present a unified framework using the open-source tool gammapy to perform a forward-folding spectral analysis of AGN data from the optical to gamma-rays (over 11 decades in energy), enabling the full incorporation of instrument response functions and astrophysical backgrounds, while reducing biases associated with the traditional flux point analysis. It also offers a flexible and compact data format to store and distribute the data and telescope information.

We demonstrate its capabilities with data from the quasars OP 313 and 4C +27.50, which underwent flaring activity during 2024. Our analysis includes optical data from the Liverpool Telescope, UV data from Swift-UVOT, X-ray data from Swift-XRT and NuSTAR, and gamma-ray data from Fermi-LAT. We validate the analysis against native tools for each instrument, and discuss the prospects for future multi-wavelength and time-domain astrophysical studies of AGN.

Speaker: Dr Mireia Nievas Rosillo (IAC, ULL)

18:05 Particle acceleration in Ultra Fast Outflows

Ultra Fast Outflows (UFOs) are sub-relativistic dense winds of wide aperture angle, launched from Active Galactic Nuclei, at which strong shocks (Mach number $\gg$ 1) are expected to form.

At these shocks, particle energisation through diffusive shock acceleration (DSA) should lead to the copious production of gamma rays and neutrinos, in the interaction of accelerated charged particles and the surrounding circumnuclear medium.

We model proton acceleration through DSA at UFO shocks and estimate the associated high-energy gamma-ray and neutrino fluxes, and investigate the prospects for detection with current and next generation gamma-ray and neutrino observatories.

For a selected list of nearby UFOs, we identify the best candidates for detection with next generation gamma-ray observatories such as CTAO, and discuss the potential for detection with neutrino observatories such as IceCube.

Speaker: Baptiste Le Nagat Neher

17:05 → 18:35 GA: SNR & PWN

17:05 A Fermi-LAT study of magnetar wind nebulae powering superluminous supernovae

Superluminous supernovae (SLSNe) are a recent class of astronomical transients whose luminosities exceed those of typical core-collapse supernovae by 10 to 100 times. What makes SLSNe so different from regular core-collapse SNe is still in debate. There are mainly four different energy sources being considered to explain the high peak luminosity of SLSNe: ejecta fallback accretion onto a black hole, radioactive decay of 56Ni, circumstellar interaction, or a magnetar wind nebula. Gamma-ray observations can help to constrain the emission models, and it has been predicted that gamma-ray emission from a magnetar wind nebula could be visible approximately 100 days after the explosion when the opacity decreases.
To test this hypothesis, we studied SLSNe gamma-ray light curves using 16 years of Fermi-LAT data for a sample of 6 nearby sources (< 200 Mpc) SLSNe. From this sample, we report on some hints of variability for SN 2019ieh and confirm a significant detection for SN 2017egm that coincides with the temporal and spectral predictions of the magnetar-dominated models. In particular, comparison of the models with the observed Fermi gamma-ray spectrum allows us to constrain the magnetization parameter of the nebula, which is critical for the TeV counterpart of the magnetar nebula. Based on our best model, we explore predictions for the detectability of such objects with the CTAO and the horizon of detectability. However, while the magnetar model is the most tempting model, the interaction of the shock with multiple CSM shells also offers a possible explanation.
The discovery of SN 2017egm as a gamma-ray emitter establishes a new category of gamma-ray sources and could provide a novel opportunity to investigate these extreme neutron stars, which possess millisecond rotational periods and magnetic fields of 10^14 G.

Speaker: Fabio ACERO

17:20 SNR vs PWN: who's the accelerator?

The observation of PeVatrons is without doubt one of the major breakthroughs in gamma-ray astronomy. The quest for Galactic cosmic-ray candidates goes hand-in-hand with these discoveries. However, with the advent of the very high-energy observations, many new questions arise. In many of the reported sources the origin of the particles responsible for the gamma-ray is unclear, in many cases multiple candidates exist inside the confidence region of the observation. One special case is that of  MGRO J1908+06 (LHAASO J1908+0621), where the very high-energy emission could be produced by a supernova remnant, a pulsar wind nebula or both. Using a espatial-dependent model we calculate the leptonic and hadronic emission from both sources to fit the observations. Using the multiwavelength data available, we analyse all the possible scenarios for explaining the very high-energy source and determine who is the most probable accelerator behind it.

Speaker: María Victoria del Valle (University of São Paulo)

17:35 Redefining the High-Energy gamma-ray morphology of the W51 complex with Fermi: detection of two extended components associated with W51B and W51C

The W51 giant cloud is one of the largest star-forming regions in the Galaxy. Several experiments have detected gamma-ray emissions from the W51 complex: Fermi (Jogler and Funk 2016), MAGIC (Aleksic et al. 2012), HESS (H.E.S.S. Collaboration et al. 2018), HAWC (Albert et al. 2020), and more recently, LHAASO (Cao et al. 2024). This complex contains two star-forming regions, known as W51A and W51B, as well as the middle-aged supernova remnant (SNR) W51C. This last has been detected in the High-Energy (HE) gamma-ray band and is associated with the latest $\textit{Fermi}$ catalogue source 4FGL J1923.2+1408e. The observed pion-bump feature advocated for a hadronic scenario where the proton accelerated at the SNR shock level interacted with the dense molecular clouds to produce gamma rays via $\pi_0$-decay. The spectral cutoff detected by LHAASO at $\sim$400 TeV might provide the first evidence of SNRs accelerating Cosmic Rays up to PeV energies. However, LHAASO's limited angular resolution precludes a precise morphological analysis, and the two young stellar clusters contained within W51B (G48.9-0.3 and G49.2-0.3) are also valid PeVatron candidates accountable for the Ultra-High-Energy gamma-ray emission.
We analyzed 16 years of $\textit{Fermi}$-LAT data on the W51 region and found an $8\sigma$ excess, improperly fitted by the current model adopted for 4FGL J1923.2+1408e in the 4FGL catalogue. We performed a binned Likelihood analysis to identify the best-fitting model for the emitting region.
We performed the spatial analysis using $\textit{gammapy}$, which includes asymmetric spatial models, between 10 GeV and 1 TeV. We compared different combinations of spatial distributions, including radio-data-based templates, to test and study the spatial correlation of the gamma-ray emission and the presence of molecular clouds around the W51C and W51B regions. We identified two overlapping extended elliptic sources, spatially coincident with the radio emission regions of W51B and W51C.
Eventually, we disentangled the HE gamma-ray emission from the W51 complex in two distinct spectral components between 1 GeV and 1 TeV: a softer LogParabola component ($\Gamma$=1.8) associated with W51C and a harder Power Law spectrum ($\Gamma$=2.4) associated with the W51B star-forming region.
We performed a multi-wavelength modelling of the two sources, including the Very-high-Energy and Ultra-High-Energy data from MAGIC and LHAASO. We confirmed the hadronic nature of both components. We studied the combination of two acceleration sites: the W51C old SNR shock, accelerating protons up to the TeV range, and the Super Bubbles originating from the stellar clusters contained in W51B, likely responsible for the PeV emission detected by LHAASO.

Speaker: Giorgio Pirola (Max-Planck-Institut für Physik)

17:50 Study of the origin of high energy gamma rays in the 2-degree range around G57.2+0.8

We report the analysis results in the 2-degree range around G57.2+0.8 by LHAASO using the WCDA data and KM2A data up to July 2024. Compared with other templates, a template with one dust and three additional sources can explain the high-energy gamma-ray emission well in this region. During the processing, the location of the TeV source (TeV J1943+213) was fixed, and the other two fitted sources may correspond to a millisecond pulsar (B1937+21) with extension around 0.55 degree, a pulsar (B1930+22) as a point source, respectively, while the former has a higher energy than the latter. The spectral energy distribution corresponding to the dust template is similar to that of the diffuse gamma-ray emision (DGE) measured by LHAASO, but the flux is about 2.0 times higher. Below 100 TeV, this flux in this region is higher than that of the gamma-ray spectrum produced by the interaction of the measured proton spectrum with the local gas, indicating the presence of local high-energy cosmic rays. Its origin may be related to G57.2+0.8.

Speaker: Houdun Zeng (Purple Mountain Observatory, CAS)

18:05 Observation of VER 2019+368 with the SST-1M stereoscopic system

The "Dragonfly" Pulsar Wind Nebula and its surroundings is a complex region with several HE to UHE gamma-ray point-like and diffuse sources accompanied by their multi-wavelength counterparts. MILAGRO discovered the VHE emission in 2012, making it the second brightest MILAGRO source in the northern hemisphere. The region was later resolved into more VHE sources by VERITAS, revealing a complex nature and suggesting an energy-dependent morphology around the core source VER 2019+368. Recently, the LHAASO observatory detected photons with energies up to 270 TeV, opening up the possibility of particle acceleration up to PeV energies. As one of the brightest and hardest sources in the LHAASO catalog, VER 2019+368 is an ideal candidate for testing the capabilities of the Single-Mirror Small Size Telescope (SST-1M) to detect extended sources.

The SST-1M is a small Cherenkov telescope designed to detect gamma rays with energies greater than about 1 TeV. The optical design of the SST-1M follows the Davies-Cotton concept to ensure good off-axis performance. The camera consists of 1296 silicon photomultiplier (SiPM) pixels and a fully digital trigger and readout system. The SiPM technology allows high night sky background operation, significantly increasing the duty cycle compared to standard photomultipliers. Two SST-1M telescope prototypes were installed in Ondrejov, Czech Republic, in 2022, and stereoscopic observations of astrophysical gamma-ray sources have been performed since then.

In this contribution, we present preliminary results of the first observing campaign of the VER 2019+368 region, performed with SST-1M from April to November 2024, resulting in 140 h of stereo data. We present the data analysis, focusing on the morphological and spectroscopic study of the region. We also present the off-axis performance of SST-1M in the context of the prospects for detecting extended galactic gamma-ray sources.

Speaker: Dr Jakub Jurysek (FZU - Institute of Physics of Czech Academy of Sciences)

18:20 Measurement of the Forward Shock Velocities of the Supernova Remnant N132D Based on the Thermal X-ray Emission

Supernova remnants (SNRs) have been widely believed to be the dominant source of Galactic cosmic rays, which are accelerated up to ~ $10^{15.5}$ eV through the process called Fermi acceleration. However, this paradigm has not been verified, as key aspects of the acceleration process, such as its mechanism and efficiency, are not well understood. Shock velocity is considered as one of the key parameters to determine the cosmic-ray acceleration efficiency, and thus it is important to constrain the velocity observationally. Here we present shock velocity measurements on the SNR N132D, based on the thermal properties of the shock-heated interstellar medium. We apply a self-consistent model developed in our previous work to X-ray data from deep Chandra observations with an effective exposure of $\sim$ 900 ks. In our model, both temperature and ionization equilibration processes in post-shock plasmas are simultaneously calculated, so that we can trace back to the initial condition of the shock-heated plasma to constrain the shock velocity. We reveal that the shock velocity ranges from 800 to 1500 km $\rm{s^{-1}}$ with moderate azimuthal dependence. Although our measurement is consistent with the velocity determined by independent proper motion measurements in the south rim regions, a large discrepancy between the two measurements (up to a factor of 4) is found in the north rim regions. This implies that a substantial amount of the kinetic energy has been transferred to the nonthermal component through highly efficient particle acceleration. Our results are qualitatively consistent with the $\gamma$-ray observations of this SNR.

Speaker: Yoshizumi Okada (Aoyamagakuin University, JAXA/ISAS)

17:05 → 18:35 OE

Convener: Anastasia Tezari (CERN)

17:05 Practical Activities for Campus Cosmic Ray Observation in China

Cosmic rays, discovered in 1912, are high-energy particles originating from outer space. They carry rich information about celestial evolution and the universe and represent the only material samples,which humans can obtain from beyond the solar system.

Cosmic ray observation touches on the frontiers of particle physics and astrophysics. The methods and instruments used in the experiments include detectors, electronics, computers, automatic control systems, Global Position System, and data transmission and processing, among other modern physics knowledge and technologies.

This report introduces the construction of China’s first campus cosmic ray observation station, the establishment of the Campus Cosmic Ray Observation Collaboration, and the expansion of cosmic ray observation activities to many schools. It also covers participation in international exchange activities and the achievements made. After five years of development, reflections and recommendations are provided for conducting such activities in different schools and regions.

The results of this series of practical explorations demonstrate that conducting campus cosmic ray observation activities, with students directly guided by scientists and teachers in real scientific research, stimulates students' curiosity, imagination, and desire for exploration. This lays a solid foundation for cultivating innovative talents in the future.

Speaker: Prof. Wenli Zheng (Institute of High Energy Physics,CAS)

17:20 The MAYORANA Project

A multidisciplinary networking on neutrino physics for exchanging knowledge and expertise and founding a scientific common field and an International School is the multi-purpose goal of the MAYORANA (MultidisciplinArY netwORking Approach on Neutrino Aspects) Project. The neutrino is a key particle for astroparticle, particle and nuclear physics. At the current state-of-the-art, the nuclear and astro/particle communities, operating independently in neutrino physics, can play a real key role providing they merge own knowledge & expertise. At the University of Catania (Italy), we identify different astro/particle/nuclear experiments (AUGER, ICARUS, JEM-EUSO, JUNO, NUMEN) active in the field. We intended to explore scientific synergies among local research groups for initiating a local networking, foster international networking with related groups worldwide, integrate local expertise on related instrumental technologies and data analysis techniques, organize an international two-years High Educational School on Neutrino Physics characterized by a multidisciplinary approach merging nuclear, particle and astroparticle aspects. The fundamental result has been the foundation (2023 First Edition) and the organization of the international MAYORANA School&Workshop, based in the Sicilian territory, with relevant social, cultural, scientific and educational outcomes. On the basis of the real and recognized success of the first edition, the Second Edition of this School will take place in June 2025. Here we will describe genesis, steps and efforts, educational results and outreach outcomes of this novel venture.

Speaker: Rossella Caruso

17:35 Undergraduate Modern Physics Laboratory Experience: Exploration of Cosmic Rays at Jungfraujoch with MiniPIX

This presentation describes a demonstration of cosmic ray physics utilizing a pixel detector at the Jungfraujoch Sphinx Observatory. Rates and types of incident radiation are compared at 439m above sea level (CERN) and at 3454m (Jungfraujoch). A MiniPIX TPX3, developed by the CERN Medipix Collaboration, along with default software is utilized for observations. A USB form factor eliminates the need for infrastructure beyond a standard laptop and can be adapted for quick educational demonstrations or more detailed studies.

Speaker: Mr Albert Parmenter (University of Dallas)

17:50 Latitude-Dependent Cosmic Ray Observations Using the Cosmic Watch Educational Detector Aboard South Korean Icebreaker ARAON

Understanding cosmic ray variations with latitude and atmospheric conditions is essential for space weather studies and particle physics education. Cosmic Watch (CW), a compact and accessible muon detector, provides a hands-on tool for studying these variations. It consists of a 5 cm × 5 cm × 1 cm plastic scintillator coupled with a silicon photomultiplier to detect scintillation light from charged particles. In this study, we deployed CW aboard the South Korean icebreaker ARAON alongside the shipborne neutron monitor “Changvan", which provides higher count statistics for atmospheric neutron detection. The detector operated inside Changvan’s insulated container during two major voyages: the Antarctic voyage (December 2023–April 2024) and the Arctic voyage (July–September 2024). The results confirm that CW count rates exhibit a latitude dependence, decreasing with increasing cutoff rigidity—the minimum momentum per unit charge (GV) required for cosmic rays to penetrate Earth’s magnetic field. We are also investigating the influence of barometric pressure on CW count rates. This study demonstrates the feasibility of CW for scientific measurements in extreme environments while promoting its role in education and outreach. The CW detector for the latitude survey was provided by Accel Kitchen. This research was partially supported by the NSRF via the Program Management Unit for Human Resources & Institutional Development, Research and Innovation (B41G680027).

Speaker: Mr Aiya Suttikulbutr (Mahidol Wittayanusorn School)

18:05 Approach to Physics Education Using Local AI with RAG for Open Educational Materials Generation

The new tool that starts to enter all parts of our life is AI – and it enters education as well. There are two large concerns with using AI for education - the safety of students’ data and the AI missing specific knowledge about the given class. The approach of using the Retrieval Augmented Generation provides the user data to the locally run LLM model (using Ollama framework, a free and open-source tool that allows you to run large language models locally on your system) as a context for the generation of the OER materials. As this AI model of user’s choice is run fully locally, no data is transmitted and it can be used to do tasks with students’ data, such as summarization of evaluations and simple grading and image recognition tasks. The background, installation highlights and use examples of different showing system performance will be presented.

Speaker: Dmitriy Beznosko (Clayton State University)

Approach to Physics Education Using Local AI with RAG for Open Educational Materials Generation.pdf

18:20 Particle sonorization based on user-centred and universal design.

Researchers have long highlighted the need for multi-modal approaches in teaching and learning environments using inclusive material, based on user-centred and universal design.
In most cases, the sonification mapping of the dataset was defined by its creator and shared as a final product or even with some musicalisation, not clearly devoted to the study of the data, the identification of features or to research.
Taking into account the increasing examples of sonification in astrophysics, the development of a sonification software that translates data in different formats into sound, which allows users to open different datasets, and explore them through visual and auditory display, the last permitting them to adjust visual and sound settings to enhance their perception, was done. It is an open-source application, based on a modular design, which allows users to open different datasets, and explore them through visual and auditory display, the last permitting them to adjust visual and sound settings to enhance their perception
The software emerged at the early stages of the REINFORCE project, and, because of this, it was possible to add multiple new functionalities and developments, including the sonification of diverse sets of data from the demonstrator-projects.
In this contribution, we present for a first time the particle sonorization, applied to two specific cases:

• New Particle search at CERN, with an innovative approach in order to be able to classify different particles using only sound.
• Cosmic Muon Images, the representation with sound was based on the possibility of correlating the deposit of energy through the three layers of the detector.

On the other hand, and after two training courses, we will present the results of impact and improvement of detection of data features using the multi-modal approach to the study of scientific data.

Speaker: Emmanouil Chaniotakis

17:05 → 18:21 SH: energetic events

17:05 Simultaneous Simulation of the Solar Energetic Protons and the Forbush Decrease in Galactic Cosmic Ray Flux Following the 14 July 2017 Event

Galactic Cosmic Rays (GCRs) are a source of major radiation hazards in space, therefore the forecast and nowcast of their spectrum time evolution during the passage of Coronal Mass Ejections (CMEs) is a desired part of radiation hazard prediction models. GCRs are generated in galactic sources and propagate until they approach the heliopause, where their Local Interstellar Spectrum (LIS) can be used as boundary condition in GCR models.

To simulate GCRs prior to the eruptive event, we need to: (a) determine the LIS at the heliopause; (b) determine the steady-state spectrum in the Inner Heliosphere (IH); (c) and model the time evolution of GCR spectra throughout the IH. Our model employs the modulation potential to quantify the average energy loss of GCRs inside the heliosphere and map the LIS to smaller heliocentric distances by accordingly reducing the LIS energies and correcting the phase volume. This provides the boundary condition for GCRs at the outer boundary of the computational domain in our model (2-6 AU). Voyager-1 measurements are used to determine the LIS, with the modulation potential evaluated either from the GALPROP-HelMod framework or from the model by Corti et al (2019).

The Poisson bracket scheme is used to solve the particle transport both for the steady-state and eruption phases, with the dynamical state of the solar wind plasma and interplanetary magnetic field simulated within the Space Weather Modeling Framework of the University of Michigan. The refined SPECTRUM model, developed by the University of Alabama, will be used to compute the GCR diffusion coefficient. The CME event of July 14, 2017, for which we have already demonstrated the SEP production results, is simulated by superposing the erupting magnetic configuration by Gibson-Low (1998) with the parameters found with the Eruptive Event Generator by the Gibson-Low tool. Synthetic results for three-day evolution of GCRs at 1 AU will be compared with Oulu neutron monitor data (see figure below), as well as data from AMS-02.

Speaker: Dr Igor Sokolov (University of Michigan)

17:20 Using Monte Carlo Simulation to Study the Pile-up Effect of CME and CIR-driven Shocks

This study employs the Monte Carlo simulation method to investigate the shock stacking effect driven by coronal mass ejections (CMEs) and corotating interaction regions (CIRs). First, a probability distribution model incorporating characteristic parameters of CMEs and CIRs—such as velocity, density, and magnetic field—was constructed to reflect their stochasticity and diversity in solar activities. Monte Carlo simulations were performed on a large number of randomly generated CME and CIR events to track the formation, propagation, and interaction processes of shocks. The simulation results revealed the conditions and influencing factors for shock stacking, demonstrating that the high-speed and high-density characteristics of CMEs, as well as the relative positions and time intervals between CIRs and CMEs, significantly affect the intensity and occurrence probability of the shock stacking effect. Further analysis examined the impact of shock stacking on Earth’s space environment, including compression of the magnetosphere and acceleration of high-energy particles. This study provides critical theoretical foundations and numerical simulation support for understanding solar wind-magnetosphere interactions and space weather forecasting.

Speaker: Xin Wang

17:35 Over-abundant gamma-like signals around Solar disk by smeared and bent electron pairs spiral secondaries feeding TeV gamma by ICS

The Sun is a target of cosmic rays , CR. Their secondary photons by such CR skimming on solar edges, while scattering solar atmosphere and making neutral pions , is one of the expected and partially observed signal. However there are discrepancies in the gamma spectra within the the Sun disk that are not well understood. We first are reconsidering the role of such skimming and scattering CR on solar atmosphere, at tens TeV , ejecting secondaries TeV neutral pions and their photons that are more penetrating and shining to Earth via a thin external corona layer. We show that this ring is too narrow to account the observed data. Also an additional wider ring , formed by more penetrating muon secondaries, is not much effective. We therefore evalueted the energetic tens TeV skimming CR on the solar limb and their relativistic bent scattered proton-proton charged secondaries. The pions and their later decayed muon and final electron pairs are considered in solar fields. The energetic electrons pair secondaries may survive in long life spirals around solar magnetic field lines, offering a key role to amplify gamma radiation by ICS on surface solar lights. This effect could be a main final photon signals, able to explain the observed overabundance of gamma HAWC events at solar limb edges. Other photon-like secondaries could be the survived TeV electron pairs in direct flight to Earth. Disentangling the different gamma signatures is possible and described in present study.

Speaker: Daniele Fargion (Physics Department, Rome University 1, Sapienza, ; Osservatorio Astronomico di Capodimonte, INAF, Italy,)

17:50 Spectra and anisotropy during GLE 74 on 11 May 2024 derived using neutron monitor data

Study of solar energetic particles is important to provide the necessary basis to understand the mechanisms of their acceleration and propagation in interplanetary space. It is known that following solar eruptive processes, such as solar flares and/or coronal mass ejections, solar ions can be accelerated to high energies, even in the GeV/n range. In this latter case, the SEP energy is great enough to induce an atmospheric cascade in the Earth’s, which secondary particles can be registered by ground-based detectors, such as neutron monitors (NMs). This class of events is known as ground-level enhancements (GLEs). A notable event occurred on May 11, 2024, observed by NMs and particle detectors aboard spacecraft in near-Earth orbit. The event was observed during the deep phase of a significant Forbush decrease and one of the strongest geomagnetic storms, which make the analysis of this event particularly challenging. Here we performed a precise analysis of NM data records and derived the spectral and angular characteristics of the SEPs leading to this GLE. We modeled the particle propagation in the Earth’s magnetosphere and atmosphere. The solar protons spectra and pitch angle distributions were obtained in their dynamical development throughout the event.

Speaker: Alexander Mishev

18:05 From Sun to ground: Particle Acceleration and transport in the inner heliosphere

The inner heliosphere, spanning from the solar corona to Earth's orbit, is a dynamic region where energetic particles are accelerated and transported. Understanding these processes is crucial for comprehending space weather phenomena and their impact on Earth. This abstract discusses the key mechanisms involved in particle acceleration near the Sun, primarily driven by solar flares and coronal mass ejections (CMEs), and the subsequent transport of these particles in the solar wind, focusing on the roles of large-scale magnetic fields and turbulence. Furthermore, we address the influence of Solar Energetic Particles (SEPs) and Galactic Cosmic Rays (GCRs) on the global electric circuit. SEPs, produced by solar flares and CMEs, and GCRs, originating from outside the solar system, both contribute to the ionization of the Earth's atmosphere. This ionization significantly impacts the conductivity of the atmosphere, particularly in the polar regions. Change of ionization due to SEPs and GCRs can alter the potential difference between the ionosphere and the ground, influencing the flow of current within the global electric circuit. These changes can lead to observable effects, such as variations in atmospheric conductivity and potential gradients, and may even influence weather patterns.

Speaker: Prof. Gang Li (Macau University of Science and Technology)

Saturday 19 July

08:30 → 09:00 Registration

09:00 → 10:30 Plenary session

09:00 Latest Results from the Alpha Magnetic Spectrometer on the International Space Station

The Alpha Magnetic Spectrometer (AMS) is a precision particle physics detector operating on the International Space Station. Since 2011, AMS has collected more than 250 billion charged cosmic rays, from elementary particles to iron nuclei with energies up to multi-TeV. The high-precision measurements with ~1% accuracy, over a solar cycle, have led to many surprising observations. The latest results on cosmic elementary particles (electrons, positrons, antiprotons, and protons) reveal unique properties and indicate new sources of particles and antiparticles. The data on nuclei and isotopes exhibit characteristic energy dependences that are not explained by current theories. The comprehensive AMS data requires a new model of the cosmos.

Speaker: Zhili Weng (Massachusetts Inst. of Technology (US))

09:45 Earth as a giant spectrometer: neutron monitor network and latitude survey

The Earth’s magnetic field acts as a natural spectrometer for cosmic rays. Because the geomagnetic cutoff rigidity varies with geographic location, particles of different energies are selectively filtered depending on their arrival direction and the position of the observer. Space based missions such as the PAMELA (Payload for Antimatter Matter Exploration and Light-nuclei Astrophysics) satellite and Alpha Magnetic Spectrometer (AMS-02) aboard the International Space Station provide high-precision measurements of charged cosmic rays, antimatter components, and solar particles in low Earth orbit illustrating the influence of the Earth’s magnetic field. Their major disadvantage is the fact that these missions cover not all cutoff rigidities for all times, so that e.g. the onset of a Solar Energetic Particle event may be missed.

The combination of high energy protons and helium can be measured by ground-based detectors, like neutron monitors. Although these detectors don’t provide the energy spectra and chemical composition a network of such detectors well placed over the provides such information. E.g. Spaceship Earth is a conceptual framework that envisions our planet as a shared vessel traveling through space based on a global real time neutron monitor network, consisting of a coordinated array of neutron monitor stations distributed across a wide range of latitudes and longitudes.

To utilize the measurements of each neutron monitor the response to the primary radiation environment including the propagation in the Earth magnetic field and the interaction of the particles in the atmosphere and in the local environment producing the secondary particle environment needs to be computed. This function is known as the Yield function that can be validated or derived independently by so called latitudinal surveys. Such latitudinal surveys are performed on a vessel that travels over a wide range of geomagnetic latitudes from the equator to the poles. The validated yield functions are utilized to invert the neutron monitor network measurements to derive the proton spectra during solar energetic particle events.

Here we review the status, developments and methodology of using a global neutron monitor network to derive space environment quantities that are relevant for space weather.

Speaker: Bernd Heinz Heber (Christian-Albrechts-Universitaet Kiel (DE))

10:30 → 11:00 Coffee

11:00 → 12:00 Plenary session

11:00 Latest results from the DArk Matter Particle Explorer space mission

The DArk Matter Particle Explorer (DAMPE; also known as ``Wukong'') is a satellite-borne, calorimetric-type particle detector that has been smoothly operating in space for more than 9 years since its launch in December 2015. DAMPE is designed to detect cosmic rays and gamma rays up to unprecedentedly high energies, benefited with its large geometric area and thick imaging calorimeter. The outstanding charge and energy resolution enable DAMPE to have a powerful potential for its major scientific goals including the indirect detection of dark matter in space, comic-ray physics, and gamma-ray astronomy. Here, we first give an overview of the DAMPE mission and its on-orbit operation status in the last 9 years. Then, we highlight the latest scientific results from DAMPE regarding cosmic-ray and gamma-ray observations.

Speaker: Chuan Yue

11:30 Solar Energetic Particles: new multi-spacecraft views with Solar Orbiter and Parker Solar Probe

Solar Energetic Particles (SEPs) can be detected in the heliosphere following their acceleration during solar flares and coronal mass ejections (CMEs). They are a key component of the space radiation environment, affecting space weather. SEP observables, including intensity profiles, spectra, composition and anisotropies, carry signatures of the energisation processes and of propagation effects experienced while the particles travel through the interplanetary magnetic field.
The launch of Solar Orbiter (SolO) and Parker Solar Probe (PSP) opened new possibilities in the study of SEPs: using their in-situ measurements, combined with those of other spacecraft such as STEREO A, SOHO and planetary missions, SEP data at several (e.g. 5 or more) locations in the heliosphere are available for a large number of events for the first time. These include events where SolO or PSP are close to the Sun, thus close to the acceleration region and minimising propagation effects. In others multiple observations at wide longitudinal separation are available.
In this talk, I will review recent multi-point observations taken with the SolO Energetic Particle Detector (EPD) and the PSP Integrated Science Investigation of the Sun (ISʘIS) and discuss how the new data, in conjunction with models, can be used to better understand SEP acceleration and transport.

Speaker: Prof. Silvia Dalla (University of Central Lancashire)

12:00 → 13:20 Lunch

12:00 → 13:20 PO-2: Posters Installation

13:20 → 15:05 CRD: acceleration

13:20 Supernova remnants in super bubbles as cosmic ray accelerators

Supernova remnants (SNRs) are often considered as the main sites of acceleration of Galactic cosmic rays, up to the knee feature in the cosmic-ray spectrum. However, their ability to accelerate particles to reach PeV energies is questionable and lacks observational evidence. Theoretical predictions suggest that only a small subclass of very young SNRs evolving in dense environments could potentially satisfy the necessary conditions to accelerate particles to PeV energies. Most such theoretical investigations are carried out either in the standard interstellar medium or in the wind of the progenitor. Since most core collapse supernovae occur in star clusters, it is important to extend such investigation to SNRs expanding in super bubbles. In this work we focus on a SNR shock propagating in the collective wind of a compact star cluster, and we study the acceleration process as a function time, with special emphasis on the maximum energy of accelerated particles. Using both analytic and numerical approaches we investigate the spectrum of accelerated particles and maximum achievable energy in the case of pre-existing turbulence in the collective wind and self-generated magnetic perturbations. We find that similar to isolated SNRs, acceleration to PeV energies is plausible only for extreme conditions achievable only in a small subset of SNRs.

Speaker: Iurii Sushch (CIEMAT, Spain)

13:35 Accelerating Ultra-High-Energy Cosmic Rays in the Bowshocks of Massive Stars within Centaurus A's Jets

Relativistic shocks are not efficient cosmic-ray accelerators because after the first shock crossing cycle the particles do not have time to isotropise in the shock upstream region. However, in the first cycle the particles get a boost $\propto \Gamma^2$, where $\Gamma$ is the Lorentz factor of the shock. We construct a model in which particles can achieve ultra-high energies by passing through multiple relativistic shocks in the jet of the nearest radiogalaxy Centaurus A.

Centaurus A is the result of a collision of two normal galaxies resulting in a fantastic jumble of star clusters. When young stars and clusters encounter the jets, the jet-ram pressure confines the stellar wind, creating a relativistic bowshock in which the mechanism described above can operate. The maximum energy depends on the number of bowshocks a single particle encounters. We show that for conservative stellar distributions and a jet Lorentz factor of about 10, we can explain particle acceleration up to ultra-high energies. This scenario has the advantage that the mass composition of UHECRs is similar to that of massive stellar winds.

Speaker: Anabella Araudo (Institute of Physics, Czech Academy of Sciences)

13:50 The effect of spatially dependent diffusion coefficient on particle acceleration at the wind termination shock of a star cluster

The wind termination shock of compact star clusters has been recently proposed as a potential site of cosmic ray acceleration. The most recent observation of gamma-ray emission up to a few PeV from Cygnus OB2 by LHAASO indicates that particles can be accelerated up to > 1 PeV in the environment of this star cluster. In this work, we study how a spatially varying diffusion coefficient downstream of the termination shock affects the maximum energy of accelerated particles. For three different turbulent cascades, the particle energy spectrum and their spatial distribution, together with the hadronic gamma-ray emission, are calculated. We find that a spatially dependent Bohm diffusion is favored to explain the LHAASO data but other interpretations are being explored.

Speaker: Ben Li (Gran Sasso Science Institute)

14:05 Implications of late-time XRT detected GRBs for particle acceleration

Relativistic shocks have been widely studied as promising sites for ultra-high-energy particle acceleration. Fruitful predictive results have been obtained from both analytical and numerical methods but require tests from observations. The gamma-ray burst (GRB) afterglows emission are believed to produced when, following relativistic shocks, high-energy electrons are accelerated and then produce multi-wavelength emissions. Thus afterglow observations provide potential information to test our current knowledge on shock acceleration. Here we focus on nine GRBs, selected for having XRT afterglow detection at ~ 10^7 seconds after the GRB trigger time with determined redshifts. Specifically we explore the constraints on acceleration models set by the maximum electron energy required by the observational data from these events.

Speaker: Zhiqiu Huang

14:20 Acceleration and Origins of Very- and Ultra-High-Energy Cosmic Rays

The origin of cosmic rays (CRs) remains an open question, with their spectrum featuring two key breaks: the knee (~3 PeV) and the ankle (~3 EeV). Ultra-high-energy cosmic rays (UHECRs) above the ankle are widely believed to originate from extragalactic sources, while the transition of galactic to extragalactic CRs occurs between the knee and the ankle. Recent observations suggest that Centaurus A contributes significantly to UHECR anisotropies, supporting the role of radio galaxies as UHECR sources. In this talk, I will present a framework based on turbulent acceleration in relativistic velocity-shearing jets. This provides a natural explanation of both multi-wavelength (MWL) observations of radio galaxies and UHECR production. Our relativistic magnetohydrodynamic and particle-in-cell (RMHD-PIC) simulations show that CRs can be accelerated near the Maximum theoretical (Hillas) limit. Using jet parameters derived from MWL modeling, we find that Centaurus A-like sources can accelerate CRs to rigidities of several EV, while Cygnus A-like sources can reach several tens of EVs. Additionally, we show that similar acceleration mechanisms in galactic ultra-luminous X-ray sources could contribute to the CR flux between the knee and the ankle.

Speaker: Jieshuang Wang (Max Planck Institute for Plasma Physics, Garching)

14:35 Evidence for the Sombrero Galaxy as an Accelerator of the Highest-Energy Cosmic Rays

Ultrahigh-energy cosmic rays (UHECRs) are the highest-energy messenger from space, with energies exceeding 1 EeV. Although UHECRs were discovered more than 60 years ago, their origin remains a mystery. Pinpointing sources of UHECRs is crucial for understanding the extreme astrophysical processes that accelerate particles to such extraordinary energies. We searched for UHECR multiplets by analyzing 17 years of data with energies greater than 40 EeV from the Pierre Auger Observatory. A spatial association is found between a multiplet of 25.7+6.2−7.0 cosmic rays and the Sombrero galaxy with a local (global) significance of 4.5 𝜎 (3.3 𝜎). The Sombrero Galaxy hosts a one-billion-solar-mass supermassive black hole and exhibits large-scale radio lobes and jets. Our finding provides critical evidence on active supermassive black holes as the source of the highest-energy cosmic rays.

Speaker: Haoning He

14:50 Time-dependent Acceleration and Escape of Charged Particles at Traveling Shocks in the near-Sun environment: the case of the Sept 5th 2022 Parker Solar Probe event

The Parker Solar Probe (PSP) approaches to the Sun in the past 6 years unveiled a broad variety of Traveling shocks (Ts) in the near-Sun environment, from the very weak Ts that would have been unlikely classified as shocks at 1 AU and are not associated with significant enhancement of energized particles, to the fastest ever Ts in-situ measured in the heliosphere, with unprecedented early-on signatures of particle (ions and electrons) acceleration. The interpretation of these measurements requires incorporating in particle acceleration models the time-evolution, and the escape from the accelerating source, before a steady-state is reached. We present the time-dependent version of a recently proposed 1D transport model that incorporates particle escape at all supra-thermal energies (not only the highest energies) into the diffusive shock acceleration (DSA) model via an energy- and position- dependent escape time; two cases of negligible (or not) self-excited magnetic field fluctuations in the upstream of the shock are solved. In the former case the scattering is dominated by pre-existing solar wind turbulence and the average time scale for particle acceleration at various heliocentric distances, from 1 AU down to the inner heliosphere (< 0.1 AU), is shorter than in the no-escape case as higher energy particles have a shorter time to accelerate before leaking out into the upstream and never return. A simple scaling with time of the time-dependent energy spectrum is provided. We present also the solution of the case of a non-negligible self-excited turbulence. Finally we compare the ``nose'' structure at a few hundreds keV protons first measured in situ by PSP in crossing the very fast September 5th 2022 Ts at 0.07 AU; we find that the nose is reasonably well explained by a lack of the highest energy particles not yet produced by the young shock by both our model and the no-escape DSA version. A larger sample of such events by PSP will help identify the conditions in the Ts lifetime of an escape-dominated regime.

Speaker: Federico Fraschetti (Center for Astrophysics | Harvard & Smithsonian)

13:20 → 15:05 CRI: radio detection

13:20 First Data of the 3000km2 Radio Detector at the Pierre Auger Observatory

In this contribution, we present the status and first data from the Radio Detector (RD) at the Pierre Auger Observatory, consisting of 1660 radio antennas deployed across the 3000 km² surface detector array. These antennas measure the radio emission from extensive air showers in the 30–80 MHz band, enabling electromagnetic energy measurements for air showers with zenith angles above 60°. Combined with the muonic measurements from the water-Cherenkov detectors (WCDs), this allows mass composition studies at the highest energies. The large-scale deployment of the RD began in June 2023 and was completed in November 2024. A full end-to-end calibration shows consistency between Galactic and in-lab calibration to better than 5% and includes continuous monitoring for hardware failures, ensuring, for example, antenna alignment within 5°. In addition, a new electric field mill network is in place to monitor thunderstorm conditions. The calibrated event reconstruction of the RD delivers an expected electromagnetic energy resolution of 6%. We present the first data, demonstrating a strong correlation between the electromagnetic energy measured by the RD and the total shower energy measured by the WCD, confirming that the full detector chain—including triggering, data readout, absolute calibration, and reconstruction—is understood at the 5% level. We highlight a particularly impressive 36 EeV shower at a zenith angle of 85°, producing a 50 km-long radio footprint, showcasing the unique capabilities of this detector.

Speaker: Jörg Hörandel

13:35 Cosmic-ray air showers as detected with the shallow antenna of RNO-G

The Radio Neutrino Observatory Greenland (RNO-G) is an in-ice neutrino detector currently under construction on top of the Greenlandic ice sheet. Its primary goal is to achieve detection of neutrinos beyond energies of $\sim$ 10 PeV. Each station is equipped with log-periodic dipole antennas (LPDA) oriented toward the sky, which play a crucial role for background reduction in the neutrino search. Furthermore, these antennas enable the detection of radio emission from cosmic-ray air showers. Other experiments have already shown that the radio emission of air showers allows for precision measurements of cosmic-ray properties. Upon completion of its planned 35 stations, RNO-G will be covering an area of $\sim$ 50 $\mathrm{km}^2$, making it a medium-sized cosmic-ray detector as well. A unique feature of RNO-G is its high-altitude location ($\sim$ 3000 m), which allows the study of shower cores impacting the air/ice interface and further developing in the ice itself. Moreover, RNO-G provides an opportunity to study high-energy muons, created in cosmic-ray induced air showers.

In this contribution, we will present the final results of the first analysis utilizing the shallow LPDAs to detect radio emission from cosmic-ray air showers. We will present the analysis methodology and discuss the detected cosmic-ray events, including a discussion of their reconstructed properties.

Speaker: Jakob Henrichs (DESY)

13:50 Recent Highlights from the Auger Engineering Radio Array

The Auger Engineering Radio Array (AERA) has played a pioneering role in the development of radio detection techniques for cosmic rays. Consisting of 153 autonomous antenna stations deployed over 17 km², AERA measures the radio emission from extensive air showers initiated by cosmic rays with energies between 0.1 and 10 EeV in the frequency range of 30 to 80 MHz. As the largest cosmic-ray radio detector worldwide before the AugerPrime Radio Detector (RD), AERA has advanced the understanding and capabilities of radio measurements at ultra-high energies. It is operated in coincidence with the other detectors of the Pierre Auger Observatory, particularly the Surface Detector (SD) and the Fluorescence Detector (FD). AERA has served as a testbed for novel analysis techniques that will be employed in future studies with the RD. In this contribution, recent highlights from AERA are discussed. We report on measurements of the depth of the shower maximum using the radio footprint, demonstrating compatibility and competitive resolution with established FD results. An absolute calibration of AERA is achieved by monitoring the sidereal modulation of the diffuse Galactic radio emission for nearly a decade, confirming the long-term stability of a radio detector with no significant aging effects observed. This stability suggests that radio detectors could also be used to monitor potential aging effects in other detector systems. Additionally, we investigate the muon content of inclined air showers using hybrid SD-AERA events. Our results indicate that the muon content in measured data is consistent with expectations for iron nuclei as predicted by current-generation hadronic interaction models, confirming the well-known muon deficit for the first time with radio data. These findings reinforce the value of radio detection for cosmic-ray studies and provide a foundation for the next generation of analyses with the AugerPrime RD.

Speaker: Marvin Gottowik

14:05 Progress of the GRANDProto300 Project

GRANDProto300 is a pioneering prototype array of the GRAND experiment. It consists of 300 radio antennas and will cover an area of $200\, \text{km}^2$ in a radio-quiet region of western China. Serving as a test bench for the GRAND experiment, GRANDProto300 aims to achieve autonomous radio-detection and reconstruction of highly inclined air showers. It is designed to detect ultra-high-energy cosmic rays in the energy range of $10^{16.5} - 10^{18}\, \text{eV}$ at a rate comparable to that of the Pierre Auger Observatory. Over the past two years, significant improvements have been made to both the hardware and firmware of GP300. Currently, 50 detection units have been deployed at the site. We present the current status of detector commissioning, including updates on hardware, calibration results such as GPS timing and antenna positioning. Additionally, we discuss the observation of solar radio bursts associated with solar flares, the galactic radio emissions detected, and preliminary cosmic-ray searches.

Speaker: Yi Zhang (Purple mountain observatory)

14:20 Progress on air shower observations with the SKA

Construction of low frequency component (50 - 350 MHz) of the Square Kilometre Array has started in Australia. With an immensely dense core of almost 60 thousand antennas within a square kilometer, the telescope provides a unique opportunity to study cosmic rays in the energy range between the knee and the ankle. High resolution observations and new analysis strategies will provide more insight into the most powerful Galactic accelerators, and the onset of the extragalactic component.

In this contribution, we describe the current state of development of the SKA cosmic-ray program and recent progress in the exploration of the science case.

An array of radio-quiet particle detectors will be deployed at the SKA-low core for the purpose of triggering. A small prototype array has recently been installed at the Murchison Widefield Array, and an upgraded design is currently being developed. The capabilities of the SKA are explored with state-of-the-art simulation codes like CoREAS, and the new template synthesis technique, that provides a huge gain in computation speed, which is indispensable for next-generation observatories like the SKA.

Using standard techniques, it is demonstrated that the SKA will achieve a reconstruction resolution on Xmax of 6 to 8 g/cm^2. However, the combination of dense ground coverage and large bandwidth allows for the development of new analysis strategies that provide additional insight in the characteristics of the primary particle and the physic in the air shower. Reconstruction of the shape of the longitudinal development and the identification of double-bump showers will put new constraints on both the mass composition and the hadronic interactions.

The SKA will be able to reconstruct showers down to energies of 10 PeV or even 1 PeV with beamforming techniques. This expands the energy range over which mass composition analysis can be performed and might even allow to observe PeV gamma-rays, if an efficient photon/hadron separation is possible.

Speaker: Stijn Buitink (Vrije Universiteit Brussel (VUB))

14:35 Detection of Cosmic Rays at High Elevation by the BEACON Prototype

The Beamforming Elevated Array for COsmic Neutrinos (BEACON) is a detector concept designed to measure the flux of Earth-skimming tau neutrinos above 100 PeV. BEACON will consist of many independent, phased radio arrays placed on mountains. The long in-air propagation length of radio together with the high-elevation sites provide BEACON with a large detector volume in an efficient manner. A prototype, consisting of a single phased array, is located in the White Mountains of California. In 2021, the phased array consisted of four cross-polarized short-dipole antennas. In 2023, the original antennas were replaced with six newly designed antennas, deployed alongside an independent array of four scintillators. The goal of the prototype is to demonstrate its ability to trigger on the radio emission of extensive air showers by first detecting cosmic rays. Here, we present cosmic ray candidates from two independent cosmic ray searches: a radio-triggered search using data from the 2021 instrument, and a scintillator-triggered search for coincident radio signal using data from the 2023 instrument. In the future, this measurement of the cosmic ray flux will be used to perform an in-situ validation of BEACON’s predicted energy threshold.

Speaker: Andrew Zeolla (Pennsylvania State University)

14:50 Cosmic Ray search for the Radar Echo Telescope for Cosmic Rays

The Radar Echo Telescope for Cosmic Rays (RET-CR), a pathfinder experiment for a future ultra-high-energy neutrino detector, is an experiment designed to detect the ionization trail from a cosmic-ray-induced particle cascade penetrating a high-altitude ice sheet. In high-elevation ice sheets, a high-energy cosmic ray (E $>$ 10 PeV) at a small zenith angle deposits more than 10 percent of its primary energy into the ice sheet, resulting in energy densities several orders of magnitude higher than in air. This dense in-ice cascade can then be interrogated with an in-ice radar system. This technique, called the radar echo method, relies on reflection of a transmitted radio wave off the ionization trail produced in a UHE particle interaction. RET-CR consists of a phased-array transmitter and an array of receiving antennas located in the ice, triggered by scintillator panels on the surface. RET-CR is a pathfinder experiment, which aims to test the radar echo method for the Radar Echo Telescope for Neutrinos (RET-N). RET-CR was deployed at Summit Station, Greenland, running from May to August 2024. We present the ongoing cosmic-ray analysis of the 2024 campaign, and initial results will be presented.

Speaker: Dylan Frikken

13:20 → 14:50 DM: charged anti-matter

13:20 Scrutinizing the impact of the solar modulation on antiproton excess

Antiprotons serve as a key target for indirect dark matter detection. Solar modulation significantly influences the search for dark matter through antiproton detection. As antiproton particles penetrate the solar system, they are affected by the heliospheric magnetic field and solar wind, especially those with rigidities below 40 GV. Recently, AMS-02 published results from an 11-year solar cycle study on antiprotons. In this analysis, we examine three methods for solving the Parker equation to systematically investigate the observed excess of antiprotons reported by AMS-02.

Speaker: Kai-Kai Duan

13:35 Advancing Anti-Deuteron Detection in Cosmic Rays: Innovations in Methods and Technologies

The search for low-energy anti-nuclei in cosmic rays provides a means to test fundamental physics questions, such as the potential existence of primordial antimatter and the nature of Dark Matter.
The “PHeSCAMI” (Pressurized Helium Scintillating Calorimeter for AntiMatter Identification) project aims to explore a novel method for identifying anti-nuclei in cosmic rays. Specifically, when anti-protons or anti-deuterons come to rest in a medium, they can form exotic atoms. In the case of a helium target, the captured antiparticle can orbit the nucleus for microseconds before annihilating. This uniquely delayed annihilation serves as a clear signature to distinguish antimatter particles from ordinary cosmic rays.
A first prototype of the pressurized calorimeter—consisting of a 1L stainless steel vessel filled with helium at 200 bar—has been tested using cosmic muons and a 70–240 MeV proton beam at the INFN-TIFPA laboratory. Currently, development is underway for an advanced calorimeter prototype featuring a 40L volume, 200 bar pressure, and a wall grammage below 1.5 g/cm², utilizing an automotive composite overwrapped pressure vessel (COPV).
As part of the same project, an additional signature for anti-deuterons has been identified when the particle stops in plastic material. The annihilation with a hydrogen nucleus can lead to the emission of an anti-neutron, which subsequently annihilates after several nanoseconds, producing a distinctive double-annihilation signature in a segmented Time-of-Flight detector.

Speaker: Luigi Ernesto Ghezzer (Trento University & INFN-TIFPA)

13:50 The GAPS Experiment: A Search for Dark Matter Using Low-Energy Antinuclei

GAPS is a long-duration balloon experiment designed to measure the flux of low-energy (< 0.25 GeV/n) cosmic antinuclei as signatures of dark matter. The GAPS instrument, which is assembled in Antarctica in preparation for its first flight later this year, will measure the antiproton flux in an unexplored low-energy range; be the first experiment optimized for cosmic antideuterons, a “smoking gun” signature for new physics; and deliver leading sensitivity to cosmic antihelium. GAPS consists of a ten-layer silicon tracker, cooled by a novel oscillating heat pipe thermal system, and surrounded on all sides by a precision timing plastic scintillator time-of-flight (TOF) and trigger system. GAPS utilizes a novel antiparticle identification technique, in which an incident antinucleus is slowed and trapped by the tracker material, forming an exotic atom. The incident particle dE/dx and velocity, characteristic de-excitation X-rays, and subsequent nuclear annihilation products uniquely identify the incident antinucleus species. This talk will cover the GAPS sensitivity and anticipated science impact on the current landscape of cosmic ray measurements, dark matter searches, and other beyond-the-Standard-Model physics investigations.

Speaker: Kelsey Yee

14:05 Estimating the performance of the GAPS detector with muon ground testing data from Antarctica

The General Anti Particle Spectrometer (GAPS) is a balloon-borne cosmic-ray experiment which prepared to launch in the past Antarctic summer season 24/25.
Its primary science goal is the search for light antinuclei in cosmic rays at kinetic energies below 0.25 GeV/n. This energy region is especially of interest for dark matter searches and is still mostly uncharted.
GAPS promises to yield unprecedented sensitivity for the search of antideuterons and will measure the low-energy antiproton spectrum with high precision. To reach the required sensitivity, the GAPS detector incorporates a new approach for antimatter detection, utilizing a tracker with custom-designed, lithium-drifted silicon detectors, designed to measure the X-ray cascade expected from antimatter capture, together with a fast time-of-flight system, allowing for a high precision beta measurement.
During the past Antarctic season, GAPS performed a pre-flight, ground calibration of the fully-integrated instrument. We present the results for track-like events obtained with muon data. This talk will highlight key results from the Antarctic ground testing campaign and present an outlook for the next Antarctic season of 25/26 for which GAPS is scheduled to launch.

Speaker: Dr Achim Stoessl (UH Manoa)

14:20 GAPS Detector Cooling System: Results from Antarctic Ground Tests

The General Anti-Particle Spectrometer (GAPS) experiment aims to elucidate the nature of dark matter by detecting antiparticles using a long-duration scientific balloon over Antarctica. The GAPS detector consists of a tracker made of lithium-drifted silicon detectors, surrounded by two layers of Time-of-Flight (ToF) plastic scintillators. To achieve an energy resolution of 4 keV FWHM in the 20–100 keV range, the silicon detectors are cooled to -40°C using Multi-loop Capillary Heat Pipes (MCHPs), specifically developed for GAPS. The MCHPs transport heat from the detectors to a radiator attached to the payload’s sidewall. On the ground, the radiator is directly cooled by the Ground Cooling System (GCS) during detector testing. The GCS consists of a chiller, a cold plate and an insulating foam.
GAPS has completed all necessary preparations during the Antarctic summer season of 2024/25. During this period, we conducted cooling tests to investigate the detector performance using the GCS. In this talk, I will present the results of the ground tests conducted during the 2024/25 season, with a particular focus on the performance of the cooling system.

Speaker: Kazutaka Aoyama (JAXA)

14:35 The GRAMS (Gamma-Ray and AntiMatter Survey) Project: Overview and Current Status

GRAMS (Gamma-Ray and AntiMatter Survey), one of the NASA Physics of the Cosmos missions, is a balloon-borne experiment utilizing a LArTPC (Liquid Argon Time Projection Chamber) detector that is potentially expandable to a future satellite mission. GRAMS aims for both MeV gamma-ray observations and antimatter-based indirect dark matter searches. With a low-cost, large-scale LArTPC detector, GRAMS can provide significantly improved sensitivities to gamma rays in a historically under-explored energy regime often referred to as the MeV Gap. GRAMS can also extensively probe a new dark matter parameter space via low-energy antinuclei measurements, including the regions suggested by the Fermi Galactic Center Excess and AMS-02 antiproton excess. We recently had a successful engineering balloon flight in Japan and an antiproton beam test at J-PARC to demonstrate our detector performance. GRAMS has been funded by NASA for a prototype (pGRAMS) balloon flight, which is planned for early 2026 from Tucson, Arizona. In this talk, I will present an overview and the current status of the GRAMS project.

Speaker: Tsuguo Aramaki

13:20 → 14:51 GA: AGNs

13:20 Pushing the VHE Frontier: LST-1’s Inaugural Detection of the Distant Quasar OP 313

In December 2023, the Flat Spectrum Radio Quasar OP 313 experienced an extraordinary very-high-energy (VHE, E>100 GeV) gamma-ray flare, reaching an integral flux of 0.3 Crab Units above 100 GeV. This event marked the first VHE detection of OP 313 by the first Large-Sized Telescope (LST-1) at the Northern site of the Cherenkov Telescope Array Observatory, delivering its inaugural scientific result and establishing OP 313 as the most distant blazar detected in this energy regime (z=0.997). Coordinated observations with LST-1, the MAGIC telescopes, and Fermi-LAT enabled us to capture the detailed spectral and temporal evolution of the flare, which we compared with a low-emission state observed in January 2024. A complementary multi-wavelength campaign—from radio through X-rays—enabled us to construct and model the broad-band spectral energy distribution within a two-zone leptonic framework. In this scenario, synchrotron and external Compton processes, involving seed photons from the accretion disk, dusty torus, and broad-line region, account for the observed emission, although several combinations of photon fields remain plausible. Furthermore, the broad energy coverage provided by our observations allowed us to probe the attenuation of VHE gamma-rays by the Extragalactic Background Light, yielding competitive upper limits on its intensity. This work not only demonstrates the breakthrough capabilities of LST-1 in VHE gamma-ray astronomy but also provides fresh insights into the complex radiative mechanisms of high-redshift blazars, paving the way for future studies of extreme extragalactic sources.

Speaker: Ryuji Takeishi

13:35 Long term multi-wavelength analysis of the Flat Spectrum Radio Quasar OP 313

The flat spectrum radio quasar OP 313 showed intense $\gamma$-ray emission from November 2023 to March 2024, as observed by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. From that event a large number of follow-up campaigns at all wavelengths started, confirming the increase of the source activity from the radio to very high energy (VHE) bands. Remarkably, it also led to the first detection of the VHE emission from OP313, making it also the most distant Active Galactic Nuclei detected at VHE $\gamma$-ray band.

In this work, we investigate this flaring period and perform a multi-wavelength analysis covering 15 years of Fermi-LAT observations, from August 2008 to March 2024. From the $\gamma$-ray light-curve study, we identified different periods of high-state activity. These are compared with the data available from other facilities. From the comparison results the trend of the light-curves in $\gamma$-rays, X-rays, UV, and optical shows an increasing flux starting from the end of 2021. Before then, the source is characterized by small flares marginally visible in the $\gamma$-ray light-curve. Instead, looking at the radio light-curves, the common trend is that the source was characterized by high fluxes from the beginning of our analysis in 2008 and, then, it shows a decreasing trend until 2019, when it started to increase again. To unveil the reason behind this different behavior and understand how radiation in different wavelengths is connected in OP 313, we focused on the study of the 7 highest $\gamma$-ray flares and of the jet's kinematics. From 3 of the 7 selected flares, we were able to produce the hysteresis pattern which gave us information about the dominating mechanism that cools down the particles in the jet. Then, from the comparison of the Spectral Energy Distributions (SEDs) of the 7 flares, we noticed that the first one is less Compton Dominated than the others. This means that different photon fields from inside and outside the jet are responsible for the detected high-energy emission. The evidence of the external seed photons' presence for the Compton scattering process was obtained through the modelization of the SEDs of 2 flares that happened at a 2-year distance, one in 2022 and one in 2024. Using a one-zone leptonic model for both of them, it results that in the recent one, the External Compton scattering of the photons coming from the dusty torus gains prominence, accompanied by a reduced synchrotron flux.

From the analysis of the visibilities of the Monitoring Of Jets in Active galactic nuclei with VLBA Experiments and VLBA-BU-BLAZAR projects from 2008 to 2024, we found new knots arising from the core of OP 313 which can be responsible for the intense flaring emission detected since 2022. From the kinematic study of these new components, we derived their epoch of ejection, the Doppler, and Lorentz factors, and the viewing angle. All these parameters quantify the jet's beaming properties.

Speaker: Chiara Bartolini

13:50 MWL Follow-up of Candidate AGN Neutrino Emitters with VERITAS/Fermi/NuSTAR

The origin of the highest energy (>100TeV) neutrinos is still highly debated. AGN jets are capable of accelerating hadrons to relativistic speeds, a necessary step for neutrino production in photohadronic processes. A dense photon field, such as UV emission line photons from the broad-line region, can serve as a sufficient target for photohadronic interactions to produce neutrinos. However, blazar jets can outshine these emission lines, making it difficult to identify a broad-line region even when it is present — as seen in several “transitional blazars” that are candidate neutrino emitters. We present a case study of two AGN, PKS 0446+112 and PKS 1217+02, spatially coincident with IceCube neutrino events. We follow up on these sources with multi-wavelength data from a joint target-of-opportunity program with Fermi, NuSTAR, and VERITAS, searching for lepto-hadronic signatures in their SEDs and evidence of a broad-line region. These signatures could indicate the dense target photon fields and jet hadrons needed to produce neutrinos, with the goal of identifying populations of AGN most suited to neutrino production.

Speaker: Simon Filbert (University of Utah)

14:05 Neutrino-Emitting Seyfert candidates in the VHE gamma-ray sky

The Seyfert galaxies NGC 1068 and NGC 4151 have emerged as the most promising counterparts of 4.2σ and 3.0σ neutrino excesses detected by IceCube in the TeV energy range.
Gamma rays and neutrinos are co-produced at the same flux level via hadronic interactions between the parent proton population and the ambient matter and radiation in the neutrino-emitting region.Observations of NGC 1068 with the MAGIC telescopes have set stringent upper limits on its very-high-energy (VHE, E>100 GeV) gamma-ray flux, revealing the presence of a gamma-ray obscured accelerator.
With the latest MAGIC observations, similar evidence is found in NGC 4151. In this talk, I will present the first results from MAGIC observations of NGC 4151, which led to the estimation of stringent upper limits on its VHE emission. These upper limits are used to constrain the neutrino-emitting region to the vicinity of the SMBH, to about ~10³ Schwarzschild radii of the SMBH at the center of NGC 4151, using relatively model-independent opacity arguments derived from multi-wavelength observations.
These findings strongly suggest that, like NGC 1068, NGC 4151 harbors a neutrino production site that is optically thick to gamma rays, reinforcing the idea that Seyfert galaxies could be a new class of hidden cosmic-ray accelerators.

Speaker: Sweta Menon

14:20 Searching for Neutrino and Gamma-Ray Coincidences with the IceCube and HAWC Observatories

While much work has gone into associating neutrino emission with various sources, very few sources have emerged. With the recent publication of IceCube Event Catalog (IceCat-1), the IceCube neutrino observatory has released a list of the most promising astrophysical neutrino events since operations began in 2010. Using the archival data from the High Altitude Water Cherenkov (HAWC) gamma-ray observatory, we perform a coincidence search for gamma rays and neutrinos using a Bayesian Block algorithm with the public IceCube alerts from IceCat-1 and the Astrophysical Multimessenger Observatory Network (AMON). Of the 350 alerts considered, 25 detections were found, with 1 coinciding with the flaring HAWC source Markarian 421, an active galactic nuclei. We present the performance of this method and a discussion of physics implications.

Speaker: Ian Herzog (Michigan State University)

14:35 Detection Prospects for AGNs with the Cherenkov Telescope Array

The Cherenkov Telescope Array Observatory (CTAO) is the next-generation ground-based gamma-ray observatory, designed to enhance sensitivity and energy coverage (20 GeV -- 300 TeV) over current Imaging Atmospheric Cherenkov Telescopes (IACTs). The instrument's specifications will enable detailed Active Galactic Nuclei (AGN) studies in the very-high-energy (VHE) regime. Predicting the AGN population detectable by CTAO is challenging due to uncertainties in flux extrapolations from lower energies to the VHE domain. Using Fermi-LAT catalogs and measures of the long-term variability of the sources, we refine detectability estimates, evaluate AGN populations under different scenarios, and compare them with spectral models from current IACTs. We assess variability effects and the detectability of distant sources. Our results identify the most promising AGNs for CTAO, indicating that CTAO will significantly expand the scope of current IACT detections, including fainter and more distant sources previously undetectable in the VHE regime. These findings support CTAO’s extragalactic task force in optimizing observational strategies and refining AGN population models.

Speaker: Luana Passos Reis (Universidade de São Paulo (IAG-USP))

13:20 → 14:51 GA: pevatrons & novae

13:20 Large zenith angle observation of the PeVatron candidate SNR G106.3+2.7 with the LST-1 and the MAGIC telescopes

Imaging Atmospheric Cherenkov Telescopes (IACTs) are ideal for investigating the nature of moderately extended gamma-ray sources at very high energy thanks to their optimal angular and energy resolution compared to ground array detectors.

The Supernova Remnant SNR G106.3+2.7 is one of the most promising Galactic hadronic PeVatron candidates. We carried out observations using the Large-Sized Telescope prototype (LST-1) of the Cherenkov Telescope Array Observatory (CTAO) and the two neighboring IACTs of the MAGIC experiment at large zenith angle (LZA) to enhance the effective area at energies above tens of TeV.

Data reconstruction and analysis are challenging due to the increased atmospheric depth and strong dependency on the zenith angle of the image properties. Therefore, specialized LZA reconstruction and analysis tools have been developed. We present a joint analysis of data from several telescope combinations, based on currently available statistics, including a preliminary study of the energy-dependent morphology and spectral models.

Speaker: Marie-Sophie Carrasco (Aix Marseille Univ, CNRS/IN2P3, CPPM, Marseille, France)

13:35 Multiwavelength study of Galactic PeVatron LHAASO J0341+5258

Galactic PeVatrons are astrophysical sources accelerating particles up to a few PeV (~10^15 eV). The primary method to identify both electron and proton PeVatrons is the observation of gamma-ray radiation at ultra-high energies (UHE, E>100 TeV). In 2021, LHAASO detected 14 steady gamma-ray sources with photon energies above 100 TeV and up to 1.4 PeV. Most of these sources can be plausibly associated with objects such as supernova remnants, pulsar wind nebulae, and stellar clusters. However, LHAASO J0341+5258 is detected as an unidentified PeVatron, emitting gamma rays at energies above hundreds of TeV. It is extended in nature and notably bright, with a flux > 20% of the Crab Nebula's flux above 25 TeV. Therefore, multiwavelength observations are required to identify the PeVatron responsible for the UHE gamma rays, understand the source morphology and association, and shed light on the emission processes. Here, we will present the results of VERITAS and HAWC observations of this PeVatron, along with multiwavelength modeling, which will help us establish the nature of this unique source and its emission mechanisms.

Speaker: Dr Priyadarshini Bangale (Temple University)

13:50 Spatial distribution of secondary electrons’ Synchrotron emission: property and implication

Galactic $\gamma$-ray sources can be produced by either high-energy protons via proton-proton collisions or electrons/positrons via inverse Compton scattering. Distinguishing between the hadronic and leptonic origin of $\gamma$-ray emission in Galactic sources remains challenging. Measurements of non-thermal X-ray spectra of these sources, which could originate from primary electrons in the leptonic scenario or secondary electrons/positrons in the hadronic scenario, have been suggested as an efficient way of discriminating between these scenarios. In this work, we investigate the morphology of the X-ray emission from secondary electrons/positrons. By calculating the surface brightness profile and spectra of X-ray emission, we find that secondary electrons produce a distinctively flat X-ray surface brightness profile. Our results suggest that, in addition to the X-ray spectrum, the X-ray morphology is crucial to determine the radiation mechanism of ultrahigh-energy $\gamma$-ray sources and help to identify sources of PeV cosmic rays.

Speaker: Qizuo Wu (Nanjing University)

14:05 Observational prediction of gamma-ray emission from knee-energy cosmic rays accelerated by core-collapse supernovae shock wave

Galactic cosmic rays are widely believed to be accelerated via the diffusive shock acceleration (DSA) mechanism at supernova remnants (SNRs). However, recent observations of SNRs with ages on the order of $10^2$ to $10^3$ years suggest that the maximum energy of accelerated cosmic rays does not reach the PeV scale. In contrast, Inoue et al. (2021) demonstrated through kinetic-MHD simulations that cosmic rays can be energized up to $3\, {\rm PeV}$ when a blast wave shock propagates through a dense circumstellar medium (CSM) within several tens of days post-explosion. Their model assumes that this dense CSM originates from a red supergiant (RSG) stellar wind with a mass-loss rate of $10^{-3}\, {\rm M_{\odot}\, yr^{-1}}$, a scenario supported by recent supernova observations. To confirm PeV-scale acceleration, detecting $100\, {\rm TeV}$ gamma-rays produced via neutral pion decay by PeV cosmic rays can serve as a key observational probe. However, such hadronic gamma-rays from very young SNRs are likely attenuated due to interactions with soft photons from the supernova photosphere and cosmic background radiation. Previous studies have suggested that detecting these gamma-rays is highly challenging if the CSM originates from a conventional RSG wind with a mass-loss rate of $\sim 10^{-5}\, {\rm M_{\odot}\, yr^{-1}}$. In this work, we utilize the kinetic-MHD simulation data from Inoue et al. (2021) to compute the gamma-ray flux emitted by a blast wave shock propagating through a dense CSM, accounting for environmental attenuation effects. Our results indicate that, assuming a modern RSG wind with a mass-loss rate of $\sim 10^{-3}\, {\rm M_{\odot}\, yr^{-1}}$, the expected gamma-ray flux is significantly higher than previously estimated. We predict that the Cherenkov Telescope Array could detect $100\, {\rm TeV}$ gamma-rays within 50 hours of observation if a Type II supernova occurs in a nearby galaxy within $7.4\, {\rm Mpc}$. Based on observed star formation rates, such an event is expected to occur approximately once every four years.

Speaker: Mr Tomotaka Nishikawa (Nagoya University)

14:20 H.E.S.S. observations of Fermi-LAT detected novae

Novae are thermonuclear explosions occurring on the surface of a white dwarf in a binary system. These explosive events are detected across multiple wavelengths, from radio to X-rays, mostly due to thermal emission. However, in 2010, Fermi-LAT unexpectedly detected gamma-ray emission from the nova V407 Cyg, challenging prior expectations, as novae were not considered capable of accelerating particles to energies yielding GeV emission. In response to this discovery, the H.E.S.S. collaboration initiated a nova observation program, which led to the detection of TeV emission from the exceptionally bright recurrent nova RS Ophiuchi. This success has reinvigorated our ongoing nova observation campaign, including other recurrent novae, such as the imminent T Coronae Borealis one. In this presentation we will present the H.E.S.S. nova ToO programme, and in particular observations of the bright nova YZ Reticuli (2020) and the GeV characteristics revealed during its two-week detection by the Fermi-LAT. This analysis of the GeV-TeV range provides crucial insights into the particle acceleration mechanisms at work in novae, shedding light on the role of shocks in producing high-energy emission.

Speaker: Paul Fauverge

14:35 A 3D Cosmic Ray Proton Density map in the Local Galaxy

Cosmic rays (CRs) are among the non-thermal components of the interstellar medium (ISM) that are ubiquitous throughout the Galaxy. While CR number density can be inferred from local measurements on the Earth, their 3D distribution has largely been explored through simulations. A data-driven 3D map of CRs is essential to better understand the spatial distribution of CRs and to probe the distribution of their sources.

Considering emission related to interactions of CRs with other components of the ISM as tracers of the CR distribution, we focus on the inelastic hadronic collision of CRs with protons in the ISM, which produces gamma rays. We use gamma-ray data from the Fermi Large Area Telescope (LAT) together with a 3D dust map to infer the spatial distribution of cosmic ray protons (CRp) in a morphological matching approach. We infer the CRp density using numerical methods based on information field theory.

We provide our 3D CRp density map as a set of samples that account for statistical uncertainties. Our map shows a smooth but inhomogeneous distribution of CRps and extends in heliocentric distance from 70 pc to 1.25 kpc.

In this talk, I will explain how we build our prior model of the CRp density and discuss our morphological matching approach. I will show the resulting 3D CRp density map and highlight the challenges in CR tomography and the current state of the project.

Speaker: Hanieh Zandinejad (Max Planck Institute for Astrophysics, Garching)

13:20 → 14:51 NU: highlights & analysis

13:20 The status and astrophysics results of the Baikal-GVD neutrino telescope

The Baikal-GVD neutrino telescope is a cubic-kilometer scale neutrino
detector being constructed in Lake Baikal. Presently the detector array
consists of 13 sub-arrays (clusters), including in total 114 strings
holding 4104 optical modules. The telescope's sensitive volume for
high-energy cascade detection has reached 0.6 km^3. In this report we
discuss status of the detector and present first physics results obtained using the data collected in 2018 -- 2024. This includes a diffuse astrophysical neutrino flux measurement using cascade-like events, with a statistical significance exceeding 5 sigma. We also discuss Baikal-GVD results on the Galactic neutrino flux, as well as searches for point-like neutrino sources and multi-messenger transients.

Speaker: Grigory Safronov

13:35 Diffuse neutrino flux measurements with the Baikal-GVD neutrino telescope abstract

We report on the observation of the diffuse cosmic neutrino flux with the Baikal-GVD neutrino telescope. Using cascade-like events collected by Baikal-GVD in 2018–2023, a significant excess of events over the expected atmospheric background is observed. This excess is consistent with the high-energy diffuse cosmic neutrino flux observed by IceCube. The null cosmic flux assumption is rejected with a significance of 5.3σ.

Speaker: Dr Rastislav Dvornicky (Comenius University in Bratislava, Slovakia)

13:50 Probing the Galactic neutrino flux with Baikal-GVD

We report on Baikal-GVD measurements of the Galactic component of the high-energy neutrino flux. Using cascade-like events with estimated energy above 200 TeV recorded by Baikal-GVD during six years since 2018, we find an excess of neutrinos from low Galactic latitudes with the chance probability of $1.4\cdot 10^{-2}$. A combined analysis of our data sample and public IceCube neutrino events in the same energy range yields a p-value of $3.4\cdot 10^{-4}$. Preliminary results on the galactic ridge using Baikal-GVD track-like events are also presented.

Speaker: Batzhargal Ulzutuev (Joint Institute for Nuclear Research, Moscow Institute of Physics and Technology)

14:05 All-sky diffuse astrophysical neutrino flux with KM3NeT/ARCA data

KM3NeT/ARCA is a rapidly evolving neutrino detector in the Mediterranean Sea. The capability of the detector to measure the diffuse astrophysical neutrino flux was recently demonstrated by the observation of an Ultra High Energy neutrino of astrophysical origin. In this contribution an analysis of KM3NeT/ARCA data, employing Machine learning techniques and advanced statistical methods is presented, as well as a fit to the parameters of the diffuse flux. The latest results for the diffuse cosmic neutrino flux with KM3NeT/ARCA will be reported.

Speaker: Vasileios Tsourapis (NCSR “Demokritos”, Institute of Nuclear and Particle Physics)

14:20 Astrophysical neutrino flux measurement and search for nutau induced cascades with 11 years of IceCube data

IceCube has made measurements of diffuse astrophysical neutrino flux for all flavors up to PeV scales. The high energy (TeV-PeV) IceCube cascade sample is particularly effective at selecting electron and tau neutrinos. We present the results of Single Power Law (SPL) and Broken Power Law (BPL) flux measurements based on 11 years of cascade data. From this cascade sample, we identify high energy (~ 100 TeV) tau neutrinos by detecting a double-cascade signature produced by a charged-current neutrino interaction and the subsequent decay of the tau lepton. A Boosted Decision Tree (BDT), is employed to search for the double cascade signature achieving a significantly improved signal-to-background ratio (9:1) compared to previous analyses based on simple selection cuts. Our simulated double-cascade sample yields a high tau-neutrino purity (~90%) and good reconstruction quality (weighted mean error for reconstructed tau decay length ~ 4m). We present sensitivities for a maximum likelihood fit of the flavor composition and constraints on the astrophysical neutrino flavor ratios using this sample in combination with IceCube’s northern muon neutrino-induced track sample.

Speaker: Zheyang Chen (Stony Brook University)

14:35 Enhancing Neutrino Flavour Sensitivity in TRIDENT with Tau Neutrino Identification

The detection of the flavor ratio of astrophysical neutrinos provides valuable insight into the neutrino production mechanisms within astrophysical sources and serves as a powerful probe for new physics. Building on the exciting observation of seven tau neutrino candidates by the IceCube experiment in 2024, the TRopIcal DEep-sea Neutrino Telescope (TRIDENT), as a next-generation neutrino telescope, aims to enhance all-flavor neutrino detection, with a particular focus on improving sensitivity to tau neutrinos. This expects to be achieved through the recording of multi-channel waveforms from each PMT within the Hybrid Digital Optical Modules as well as leveraging the reduced scattering optical properties of seawater. In this talk, we present preliminary results for the expected tau neutrino identification efficiency in TRIDENT and demonstrate its ability to determine the neutrino flavor ratio of the diffuse astrophysical flux.

Speaker: Wei Tian (Tsung-Dao Lee Institute, Shanghai Jiao Tong University)

15:05 → 16:00 Tramways to CERN

16:00 → 00:00 STELLAR

Monday 21 July

08:30 → 09:00 Registration

09:00 → 10:30 Plenary session

09:00 Gamma-ray emission and the physics of microquasars

Microquasars are jetted binary systems composed of an accreting compact object—typically a black hole—and a donor optical star. They exhibit bright emission across the entire electromagnetic spectrum, with prominent non-thermal leptonic components, particularly in the radio and soft gamma-ray bands. However, their contribution to the Galactic cosmic-ray spectrum remains unclear. Recent detections of several microquasars by HAWC, HESS, and LHAASO in the very-high-energy (VHE; >100 GeV) and even ultra-high-energy (UHE; >100 TeV) regimes have demonstrated that particle acceleration in these systems is remarkably efficient. This makes microquasars excellent natural laboratories for studying the acceleration, transport, and radiation of ultrarelativistic particles. Preliminary analyses suggest that microquasars may contribute significantly—if not dominantly—to the cosmic-ray spectrum around the knee region.
In this talk, we present an overview of both historical and recent observational results and discuss their implications for our understanding of the physical processes taking place in these enigmatic sources.

Speaker: Dmitriy Khangulyan

09:45 Probing UHECR sources - constraints from cosmic-ray measurements

Ultra-high-energy cosmic rays are the most energetic particles known - and yet their origin is still an open question. However, with the precision and accumulated statistics of the Pierre Auger Observatory and the Telescope Array, in combination with advancements in theory and modeling - e.g. of the Galactic magnetic field - it is now possible to set solid constraints on the sources of UHECRs. The spectrum and composition measurements above the ankle can be well described by a population of extragalactic, homogeneously distributed sources. Using additionally the observed anisotropy in the arrival directions, namely the large-scale dipole >8 EeV as well as smaller-scale warmspots at higher energies, even more powerful constraints on the density and distribution of sources can be placed. Yet, open questions remain - like the striking similarity of the sources that is necessary to describe the rather pure mass composition above the ankle, or the origin of the highest energy events whose tracked back directions point towards voids. The current findings and possible interpretation of UHECR data will be presented in this review.

Speaker: Teresa Bister

10:30 → 11:00 Coffee

11:00 → 12:00 Plenary session

11:00 The KM3NeT neutrino telescope: status and recent results

The KM3NeT multi-site detector is designed to detect and study cosmic neutrinos and their sources in the Universe, as well as to improve the intrinsic neutrino properties knowledge. Comprising two underwater Cherenkov neutrino telescopes located at two deep-sea sites in the Mediterranean, the KM3NeT infrastructure includes KM3NeT-ARCA, offshore Portopalo di Capo Passero (Sicily, Italy), which started to study high-energy astrophysical neutrinos, and KM3NeT-ORCA, offshore Toulon (France), designed to measure atmospheric neutrinos at a few GeV and investigate their oscillations within the Earth.

Despite being in a partial configuration, both telescopes have already yielded groundbreaking physics results, including the detection of an ultra-high-energy astrophysical neutrino, KM3-230213A. This significant observation highlights the remarkable capabilities of deep-sea neutrino telescopes and underscores their potential to uncover novel astrophysical phenomena. This contribution will review the key physics results achieved so far with ARCA and ORCA in the field of neutrino (astro)physics, demonstrating the promise of the KM3NeT detector in shaping the future of neutrino research.

Speaker: Damien DORNIC (CPPM)

11:30 Recent Progress of the Telescope Array Experiment

The Telescope Array (TA) experiment has been observing ultrahigh-energy cosmic rays (UHECRs) using a surface detector (SD) array and fluorescence detector (FD) stations since 2008. TA is the largest UHECR observatory in the Northern Hemisphere. It has been expanded by constructing additional SDs and FDs to extend its energy coverage toward both lower and higher energies. These extensions are called the TA Low Energy Extension (TALE) and the TAx4 experiment, respectively. Together, they allow us to observe cosmic rays over more than five orders of magnitude in energy above $10^{15.3}$ eV. In this talk, I will begin with an overview of the experimental setup and results, and then present the latest findings, focusing on updates related to anisotropies in arrival directions and features in the energy spectra at the highest energies.

Speaker: Dr Eiji Kido (Institute for Cosmic Ray Research, University of Tokyo)

12:00 → 13:20 Lunch

13:20 → 14:50 CRD: transport

13:20 Field line separation in 3D magnetic turbulence

Transverse transport of cosmic rays in a turbulent environment can be greatly influenced by the behavior of magnetic field lines. Indeed, in the limit of infinitely small Larmor radius, charged particles would exactly follow magnetic field lines. In particular the behavior of the spread of a bundle of field lines can have consequences in several astrophysical environments. In this talk we revisit the transverse diffusion of magnetic field lines, on two folds : (i) Numerically : we perform 3 dimensional synthetic turbulence simulations is various conditions and reconstruct the running field line diffusion coefficient of the separation between two field lines , (ii) Analytically : we try to reproduce the statistics of field line separation by applying a non-perturbative method and using the Corrsin’s independence hypothesis.
The links of these results with realistic MHD simulations will be also highlighted.

Speaker: Matthieu BOUCHET (LAPTh)

13:35 Micromirror-Induced Anomalous Cosmic-Ray Transport in Galaxy Clusters

The transport of cosmic rays (CRs) across galaxy clusters reflects a reciprocal interaction across plasma scales. Large-scale processes (≳kpc) typically influence microscale behavior (~npc), but we show that microscale fluctuations from the mirror instability—inherently patchy and intermittent in nature—shape large-scale radio morphologies in galaxy clusters by mediating CR propagation. Our multi-scale simulations (hybrid-kinetic to MHD) show a scale-dependent anomalous CR transport in this heterogeneous medium, for which we present a theoretical expression, with subdiffusion dominating at small scales and advection by turbulent motions taking over at larger scales. This interplay influences radio morphologies, revealing the significant macroscopic impact of microscale physics on CR transport.

Speaker: Patrick Reichherzer (University of Oxford)

13:50 Critical Aspects of the Nested Leaky-Box Model

Anomalies in cosmic-ray (CR) fluxes, such as the rising positron flux and the flat antiproton-to-proton ratio, have called into question the standard halo model of CR transport and supposedly support alternative models, such as the nested leaky box model. Here, we test such a model in terms of both primary cosmic-ray spectra, spectra of stable and unstable nuclei and antimatter production. We find the standard version of the model should be considered as ruled out as it is in direct conflict with several observational facts and current data. We further show that the flat antiproton-over-proton ratio proves that the Galactic residence time cannot be energy-independent.

Speaker: Benedikt Schroer

14:05 The Correspondence Between Leaky-Box and Diffusion Models of Cosmic-Ray Propagation

The leaky-box model and the attendant concept of path-length distribution were invented in the mid-1960's. Even though versatile computational packages such as GALPROP and DRAGON with the diffusion approach are now available for analysis, the concepts leaky-box and the path-length distribution continue to be adopted extensively (often with an apology for their inexactitude). We show here mathematically that there is a close correspondence between the two approaches: The path-length or resident-time distributions of the leaky-box models are similar to 'impulse response functions' of complex dynamical systems and are intuitively transparent. The results provided by the leaky-box model are valid when used judiciously.

Speaker: Ramanath Cowsik (Washington University in St. Louis)

14:20 Spatial dependence of the break in the energy spectrum of cosmic rays in the new anisotropic diffusion approach

The observed spectrum of cosmic rays (CRs) measured on Earth exhibits a break around 4 PeV, known as the "knee" of cosmic rays. Recently, a significant number of studies, based on the joint analysis of experimental data obtained from experiments such as LHAASO and Fermi-LAT on ultra-high-energy gamma rays, have indicated a potential spatial dependence of this feature. It has been shown that the "universal knee," which emerges within the framework of an isotropic diffusion approach, is inconsistent with gamma-ray observations.
We present a new diffusion model of cosmic ray propagation that accounts for the anisotropy of their transport. This model is based on the calculation of the diffusion tensor components within a realistically simulated large-scale magnetic field of the Milky Way. The model parameters are consistent with contemporary understanding of the structure of the large-scale Galactic magnetic field, the dynamics of small-scale turbulent CR propagation, as well as the distribution of sources and interstellar matter. We demonstrate that transitioning to an anisotropic description of CR propagation naturally explains the spatial dependence of the spectral break, and our calculated gamma-ray fluxes from the Galactic disk in the angular ranges 15° < l < 125°, |b| < 5° (inner Galaxy) and 125° < l < 235°, |b| < 5° (outer Galaxy) are in good agreement with Fermi-LAT and LHAASO data.
In this study, the authors achieved the following: the modulation of Galactic cosmic ray (GCR) spectra in the magnetic rigidity range of 1–30 PV (the CR knee) for protons, as well as for groups of light, intermediate, and heavy nuclei was demonstrated. The spatial variations of this phenomenon were investigated. The observed spectral modulation is explained by changes in the escape mechanism, while the possible spatial dependence of the CR knee is attributed to propagation effects.

Speaker: Vladislav Borisov

14:35 Understanding the origin of the break in the cosmic-ray all-electron spectrum at around 1 TeV

Measurements of the cosmic-ray electrons plus positrons by several experiments such as CALET, DAMPE and H.E.S.S. have revealed the presence of a spectral break at around 1 TeV whose origin is still unclear. In this contribution, we explore different possibilities for the origin which include an electron source spectrum with a broken power law which is expected from the radiative cooling of electrons during their confinement inside the sources, a power law with an exponential or super-exponential cut-off as expected when the maximum energy of the electrons is limited either by free escape from the acceleration region or by radiative losses (or by the finite age of the accelerator) respectively, and a scenario with the absence of nearby potential sources. We will show that the broken power-law source spectrum best explains the observed data, and we will discuss the implications of the result on the nature of cosmic-ray escape from the source region into the Galaxy.

Speaker: Satyendra Thoudam (Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates)

13:20 → 14:50 CRI: magnetic field

13:20 The coherent magnetic field of the Milky Way halo

Recent catalogue of the Faraday rotation measures (RM) of extragalactic sources, together with the synchrotron polarisation data from WMAP and Planck, provide us with a wealth of information on the magnetic fields of the Galaxy. We combine several phenomenological components of the GMF –- the spiral arms, the toroidal halo, the X-shaped field, and the field of the Local Bubble –- to construct a model of the regular GMF outside the thin disc. We use the binned chi2 approach to fit the parameters of the model to the data. To have control over the relative contributions of the RM and polarisation data to the fit, we pay special attention to the estimation of errors in data bins. To this end, we developed a systematic method that is uniformly applicable to different data sets and takes into account individual measurement errors, the variance in the bin, and fluctuations in the data at angular scales larger than the bin size. We found that the four components listed above are sufficient to fit both the RM and polarisation data over the whole sky with only a small fraction masked out. Important improvements of our model compared to previous approaches are the account for the contribution of the Local Bubble and inclusion of the Fan region into the fit.

Speaker: Peter Tinyakov (Universite Libre de Bruxelles)

13:35 The Effect of Our Cosmic Neighborhood’s Magnetic Field on UHECR Propagation

Propagation effects play an important role in structuring UHECR data, altering their arrival directions, energy spectrum, and mass composition. Cosmic magnetic fields modify the trajectories of electrically charged cosmic rays as they travel from their sources to Earth. While small-scale magnetized structures do not significantly impact UHECR propagation, they influence our reconstruction of the large-scale magnetic field derived from synchrotron and Faraday rotation data. In this context, the Local Bubble - a cavity of hot gas surrounded by a thick, magnetized shell - is one of the most important foregrounds to consider, as it encloses the Solar system. We focus on the effects of the Galactic magnetic field, including the Local Bubble, on the study and interpretation of UHECR data.

Speaker: Vincent Pelgrims

13:50 Update on the Galactic Magnetic Field

The Unger-Farrar 2023 models of the large scale coherent magnetic field of the Milky Way give comparably good fits to the key constraining data — Faraday rotation measures of extragalactic sources and polarized synchrotron emission -- while maximizing the differences in predictions of UHECR deflections. In this talk we report on our progress in identifying intermediate-scale structures in the GMF and in developing a new model of the random magnetic field of the Galaxy. We discuss the impact of various possible intermediate-scale coherent structures on UHECR deflections and the unanticipated result that even the magnitude of the dipole anisotropy can be affected. We also discuss a preliminary result that the widely-used Planck-tune of the JF12 random field may exaggerate the “mix-master” action of the random field in the Galactic plane.

Speaker: Glennys R. Farrar (New York University)

14:05 Search for magnetic deflection multiplets using the Telescope Array surface detectors

The Telescope Array (TA) experiment has reported evidence of an intermediate-scale excess in the arrival directions of ultrahigh-energy cosmic rays (UHECRs) with energies above 57 EeV, known as the TA Hotspot. Initially reported in 2014, this excess continues to be observed with a statistical significance of approximately 3$\sigma$. However, the astrophysical origin of this excess remains unclear. To investigate potential UHECR sources contributing to this excess, we searched for multiplets--patterns in arrival directions correlated with energy due to deflection in cosmic magnetic fields. In a multiplet, higher-energy events appear closer to the source direction, while lower-energy events are deflected further from the source. Using the latest data collected by the TA surface detectors, we conducted a detailed analysis to identify multiplets and assess their correlation with possible astrophysical sources. Our results and their implications for the origin of the TA hotspot are discussed in detail.

Speaker: Dr Eiji Kido (RIKEN Cluster for Pioneering Research)

14:20 Shift of UHECR source images by the intergalactic magnetic field

We study the propagation of ultra-high-energy cosmic rays (UHECRs) in the local intergalactic magnetic field (IGMF) within a radius of <10 Mpc around the Milky Way. Assuming that the field strength is in the range of 1–3 nG and the correlation length is between 0.01 and 1 Mpc, we demonstrate that the IGMF can not only blur the source image but also shift its position, mimicking the effect of the coherent Galactic magnetic field (GMF). This introduces additional uncertainty in identifying UHECR sources due to the displacement of the source image in the IGMF. Unlike the image shift caused by the coherent GMF, which is determined by its global structure, the shift in the IGMF depends on the specific realization of the turbulent magnetic field between the source and the observer which is much more difficult to control. Finally, we apply this effect to potential sources of the UHECR excess in the Cen A region.

Speaker: Alexander Korochkin (Université Libre de Bruxelles (ULB), Brussels)

14:35 Lensing effects of ultra-high-energy cosmic rays propagating in Galactic magnetic fields

Most ultra-high-energy cosmic rays (UHECRs) are charged particles. As a result, they are deflected by magnetic fields, which can act as lenses, altering their trajectories and (de)magnifying their apparent sources. In this study, we investigate the influence of Galactic magnetic fields on the propagation of UHECRs. The deflections of UHECR trajectories can lead to phenomena such as the appearance of multiple images of a source and modifications in its observed energy spectrum. Using realistic models of Galactic magnetic fields, such as the $\texttt{JF12}$ (Jansson and Farrar) and $\texttt{KST24}$ (Korochkin, Semikoz, and Tinyakov) models, we analyze the (de)magnification effects over a rigidity range from 1$\,\mathrm{EV}$ ($\equiv 10^{18}\,\mathrm{V}$) to 100$\,\mathrm{EV}$, and study their dependence on the chosen model. Since the deflections induced by the magnetic fields depend on the particle's rigidity, their effect varies among different nuclear species. Consequently, our findings can have implications for interpreting mass-composition and anisotropy observations, as the rigidity-dependent deflections directly alter the observed UHECR arrival direction distribution.

Speaker: Dr Danelise de Oliveira Franco (II. Institute for Theoretical Physics, Universität Hamburg)

13:20 → 14:35 GA: GC, bubbles, galactic CR

13:20 Detection of a very-high-energy gamma emission at the base of the Fermi Bubbles by H.E.S.S.

The H.E.S.S. array of imaging atmospheric telescopes is observing the Galactic Center since more that 20 years. The H.E.S.S. collaboration carried out deep very-high-energy (VHE, E>100 GeV) gamma-ray observations in a 25 degree squared region near the Galactic centre devised to reach the best sensitivity to VHE gamma-ray diffuse emission. We report here on the detection by H.E.S.S. of a VHE emission in the TeV energy regime coincident with the base of the Fermi Bubbles’ emission detected in Fermi-LAT observations. Possible emissions scenarios are discussed.

Speaker: Dr Emmanuel Moulin

13:35 Fermi and eROSITA Bubbles as "by-products" of Galactic Evolution

The Fermi and eROSITA bubbles (FBs and eRBs) are the largest gamma-ray and X-ray emitting objects in the sky, respectively. They look like nearly symmetrical pairs of bubbles rising above and below the center of our Galaxy. The FBs extend about $50^\circ$, and their emission mechanism is under debate, whether the leptonic scenario (inverse Compton scattering by relativistic electrons) or the hadronic scenario (decay of $\pi^0$ particles produced by collisions between relativistic protons and target nuclei in thermal gas). The eRBs extend up to $\sim80^\circ$ and are dominated by thermal X-ray emission. In the last decade, most of the literature suggested that the FBs and eRBs were formed by $\sim10$ Myr past Galactic Center (GC) burst-like activities, implying that the bubbles are evanescent structures of the Milky Way Galaxy (MW). However, the actual formation mechanisms are still unknown.

Linearly polarized radio observations have also reported such bilobal giant structures (hereafter Giant Radio Lobes, GRLs, Carretti et al. 2013). Several bright filamentary substructures in the GRLs trace the corresponding parts of the FBs and eRBs very well. The polarization observations also show that the magnetic fields above and below the Galactic disk are perpendicular to the disk everywhere. These facts strongly support the existence of outflows from the disk. However, the filamentary substructures may rule out a simple bubble-like morphology of the outflow.

The outflow from the Galactic disk is also strongly motivated to explain the total amount of metals in the current disk, $\sim10^7~M_\odot$, which is estimated with the typical metallicity of $Z_\odot\sim0.01$ and the total mass of gaseous matter within the star-forming region of the disk $\sim10^9 M_\odot$ (e.g., Misiriotis et al. 2006). Without the outflow from the Galactic disk, the metal amount would be much larger than the above estimate: The star formation in the MW has continued at a rate of $\dot{M}_{\rm sf}\gtrsim3 M_\odot$ yr$^{-1}$ during the cosmic-age of $t_{\rm age}\sim14$ Gyr (Haywood et al. 2016). The Salpeter initial mass function gives a fraction of massive stars as $f_{\rm ms}\sim0.1$. From the ratio of the metal mass of the supernova ejecta to the mass of the progenitor star as $f_{\rm ej}\sim0.1$ (e.g., Sukhold et al. 2018), we obtain the total mass of metals ejected by the supernovae during the cosmic-age as $M_Z\sim f_{\rm ej}f_{\rm ms} \dot{M}_{\rm sf}t_{\rm age}\gtrsim4\times10^8 M_\odot\gg10^7 M_\odot$. Thus, $\gtrsim97$ % of the ejected metals should be removed from the disk by the outflow (Shimoda et al. 2024). The observed mid-infrared large structure around the GC (Bland-Hawthorn et al. 2003) may be the evidence of the outflow that removes `missing' metals.

To be motivated by the above scenario of the MW evolution scenario, we construct a simplified model for the FBs and eRBs. We find that the Galactic wind scenario can reproduce the bubbles during $\gtrsim1$ Gyr as `by-products' of the MW evolution. This result also implies that the bubbles are "by-products" of the Galactic evolution, and gamma-ray emissions above the Galactic disk can be important clues for the Galactic evolution.

Speaker: Jiro Shimoda (Institute for Cosmic Ray Research, The University of Tokyo)

13:50 Reproducing the GeV Galactic Center Excess Using CALET Data

The Calorimetric Electron Telescope (CALET) currently has more than nine years of high-energy γ-ray data that has not been fully explored. A region of particular interest for γ-ray astronomy is the Galactic Center (GC). Analysis of Fermi Large Area Telescope (LAT) data shows an excess of GeV γ rays from the GC region that could possibly be explained by the annihilation of weakly interacting massive particles (WIMPs) or an unresolved population of millisecond pulsars. Here we present the analysis of the Galactic Center using CALET data.

Speaker: Audrey Coleman

14:05 TeV Gamma-Ray Diffuse Emissions in the Galactic Center Region with CTAO LST-1

Imaging Atmospheric Cherenkov Telescopes (IACTs), including H.E.S.S., MAGIC, and VERITAS, have detected very-high-energy gamma rays from the central region of the Milky Way. The PeVatron hypothesis posits that the supermassive black hole Sagittarius A* (Sgr A*) accelerates cosmic rays to PeV energies, producing a diffuse gamma-ray emission extending up to tens of TeV across the central molecular zone. However, previous IACT studies have yielded inconsistent results due to methodological differences, complicating direct comparison and interpretation. H.E.S.S. initially suggested a power-law spectrum within the sector-annulus region (20-60 pc) around Sgr A*, whereas the MAGIC telescopes recently presented a 2-sigma hint of a spectral cutoff at ~20 TeV for the total ridge emission (~200 pc), although H.E.S.S. and VERITAS have not obtained a sign of cut-off for that emission.

The first Large-Sized Telescope (LST-1) at the Northern site of the Cherenkov Telescope Array Observatory (CTAO) offers enhanced TeV sensitivity, despite its higher energy threshold, at large zenith angles. Its wide field of view (~ 4.5 deg) enables more uniform Galactic ridge coverage than other Northern IACTs. In this study, LST-1 observations reconfirm a spectral cutoff around 20 TeV with a significance of about 3 sigma over a pure power law, demonstrating its capability of TeV observations of extended sources and refining our understanding of cosmic-ray acceleration in the Galactic Center.

Speaker: Shotaro Abe (ICRR, UTokyo)

14:20 Measurement of the Proton Spectrum with the MAGIC Telescopes

Recently, precision measurements of cosmic rays have revealed spectral structures that deviate from the previously assumed simple power law. These features offer a wealth of theoretical interpretations to obtain a consistent picture of cosmic ray acceleration, propagation and/or injection, including potential contributions from nearby sources. Among the different species, protons, the most abundant and the least charged of all nuclei in the Universe, represent an important probe to test these scenarios and understand the observed features. In this work, we report on our measurement of the proton spectrum from one to several hundred TeV. This is derived from the existing MAGIC data collected during observations of celestial gamma-ray sources. Our analysis is based on neural networks to build the energy regressors and event classifiers. This is the first measurement of the proton spectrum over a broad energy range from 1 to 500 TeV using the ground-based imaging air Cherenkov telescope technique.

Speaker: Miguel Molero Gonzalez (Institute of Astrophysics of the Canary Islands (ES))

13:20 → 14:50 GA: GRBs, FRBs, transients

13:20 Detection of TeV Rapid Variability Component Related to Prompt Emissions in GRB 221009A by LHAASO-WCDA

LHAASO first detected the onset phase of the TeV afterglow from GRB221009A and observed its
temporal overlap with the prompt emission phase, thereby offering an opportunity to detect or
constrain radiation associated with rapid variability components resembling the TeV prompt
emission in the afterglow background. The detection of TeV prompt emission could open a new
window for theoretical research on GRBs. Using data from LHAASO-WCDA, we detected potential
rapid variability components associated with the prompt emission in the afterglow of GRB221009A
at a significance level of approximately 4σ.

Speaker: Wenyu Cao

13:35 The very high energy view of gamma-ray bursts with the MAGIC telescopes

Gamma-ray bursts (GRBs) are one of the main targets for the observations of the MAGIC telescopes. As a result of the effort in improving the sensitivity of the instrument and the automatic follow-up strategy, MAGIC detected two GRBs in the very-high-energy (VHE, E>100 GeV) range, namely GRB 190114C and GRB 201216C. In GRB 190114C ($z=0.42$), the data collected by MAGIC revealed a new emission component at sub-TeV energies in the afterglow of the GRB. The very rich multi-wavelength dataset, spanning 17 orders of magnitude in energy, allowed to perform a detailed modelling of the broadband emission. The multi-wavelength data could be modelled within a one-zone synchrotron-self Compton scenario with internal g-g absorption, where the model parameters are compatible with those found in previous GRB afterglow studies below GeV energies. Similarly, GRB 201216C broadband emission could be explained using the same model, although the amount of simultaneous multi-wavelength data is reduced with respect to GRB 190114C. In particular, GRB 201216C challenged the current MAGIC detection potential, as its redshift was determined to be $z=1.1$, strongly reducing the observed gamma-ray flux but making it the most distant source detected at VHE. These two detections, accompanied by evidence of VHE emission from a few more GRBs, opened up new questions such as the presence of sub-TeV emission in different classes and phases of GRBs. In this contribution we will present the status of the MAGIC GRB follow-up program, with an highlight on its detected GRBs. Moreover we will show the results on the GRBs observed by MAGIC from 2013 to 2019 with no evidence of VHE emission, in particular for those with simultaneous X-ray observations and redshift $z<2$. We will discuss the implications of these results for GRB physics and the challenges and prospects for future GRB observations with MAGIC.

Speaker: Alessio Berti (Max Planck Institute for Physics)

13:50 Analysis of GRB 221009A Late-Time Emission Using Fermi-LAT, HAWC, and LHAASO

The gamma-ray burst (GRB) 221009A, commonly referred to as the "Brightest of all Time" (BOAT), produced photons of record TeV energies as well as an exceptionally extended afterglow across the electromagnetic spectrum. The burst was observed by the Large High-Altitude Air Shower Observatory (LHAASO) from the initial onset of very-high-energy emission (>300 GeV) until it left its field of view at {T0 + 1.7h}. From {T0 + 8h} to {T0 + 14.4h}, the burst position transited the field of view of the High-Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory. Well into this transit, at {T0 + 9.3h}, the Fermi mission’s Large Area Telescope (LAT) detected a spatially consistent event of ~400 GeV, with a relatively low probability (3e-5 ~ 4σ) of originating from an unresolved source or diffuse emission. If associated with the burst, this would be the LAT’s highest-energy GRB photon ever recorded; however, HAWC curiously found no significant detections in searches on timescales of hundreds of seconds to hours despite having ~100x the effective area at 400 GeV. To help reconcile this apparent discrepancy, we consider the data across all three observatories. We find a short-duration flare or rebrightening to be unlikely, hence focusing on the possibility that the 400 GeV event is a continuation of the decaying afterglow seen by LHAASO. Using the Multi-Mission Maximum Likelihood (3ML) Framework and a new 3ML plugin that enables HAWC transient analyses, we perform a joint LAT-HAWC spectral fit over the late-time emission period and compare this model with observations.

Speaker: Lucia Tian (NASA Goddard Space Flight Center)

14:05 Fifteen years of Gamma-Ray Burst observations at very high energies with H.E.S.S.

We present results from the High Energy Stereoscopic System (H.E.S.S.) follow-up observations of Gamma-ray Bursts (GRBs) between 2004 and 2019. We are focusing on non-detections and providing the most extensive set of very-high-energy (VHE, >100 GeV) upper limits to date. We use this catalogue to constrain the properties of VHE-detected GRBs and compare them to those detected at VHE. Our study finds that VHE-detected GRBs are not a distinct population but are instead associated with bright X-ray afterglows and low redshifts. In addition, we model the multi-wavelength emission of a few of the observed GRBs and discuss the results in the context of their obtained microphysical parameters. The results from this work help put current VHE observations into perspective and highlight the promising capabilities of next-generation instruments, such as the Cherenkov Telescope Array Observatory (CTAO), in detecting fainter and more distant GRBs at VHE.

Speaker: Edna Ruiz-Velasco (LAPP/CNRS)

14:20 TeV Afterglow of GRB 221009A without Jet Break

We present a new model for the TeV afterglow of GRB 221009A. The magnetic acceleration reproduces the rapid increase of the TeV flux in the very early phase. We consider the change in the radial structure of the circumstellar medium from homogeneous to wind-like to describe the breaks in the TeV light curve. Our results imply a highly magnetized ejecta with a significantly thick width, making the deceleration time around 400 s for observers. In our model, no early jet break is required.

Speaker: Yo Kusafuka (Institute for Cosmic Ray Research, the University of Tokyo)

14:35 Observation of the spectral turnover in the afterglow emission of GRB 221009A

Long-duration gamma-ray bursts (GRBs) are produced with ultra-relativistic jets that emerge soon after the collapse of massive stars. The highly variable prompt-emission, lasting for a few minutes, originates from the internal dissipation within the jet. This is followed by afterglow emissions, which can persist for several days. The observed afterglow, from radio to TeV energies, is typically produced by the synchrotron and synchrotron self-Compton mechanisms. However, identification of the prompt/early TeV spectral component of GRBs has been difficult because of the limited MeV-GeV sensitivity. This talk will focus on the GeV-TeV spectral component of GRB 221009A, observed in the first 20 minutes. By modeling data from LAT at early times and AGILE at later times for the GeV range, along with TeV data from LHAASO, we establish constraints on the magnetic field and electron energies involved in the relativistic shock. Although prompt/early very-high-energy gamma-ray (VHE; E>100 GeV) emission is crucial, it is not well explored due to challenges such as the short duration of GRBs, delays between MeV instrument triggers and notifications received by the pointing VHE telescopes, and the slew-time of the telescopes. In this regard, a novel observational strategy proposed to capture the prompt/early VHE emission using pointing VHE facilities (MAGIC, CTAO/LST) will be discussed. An innovative approach has been proposed for the MAGIC telescopes: responding rapidly to Fermi/GBM triggers to scan the sky localization with short exposures of tens of seconds. We will discuss the efficiency of covering the number of GRBs per year using this strategy, which could potentially be adapted for the upcoming CTAO/LST.

Speaker: Samanta Macera (Gran Sasso Science Institute)

13:20 → 14:50 GWMS

13:20 Sensitivity of the Cherenkov Telescope Array Observatory to the gamma-ray counterparts of neutrino events detected by IceCube

The identification of gamma rays in coincidence with high-energy neutrinos has a fundamental importance in the multimessenger astronomy. This type of observations is essential for constraining the source localization, determining the source type and understanding the emission mechanisms. We investigate the Cherenkov Telescope Array Observatory (CTAO) prospects for detecting the very-high-energy (VHE) gamma-ray counterparts to neutrino-emitting extragalactic sources. The performance of CTAO under different configurations (including the so-called "Alpha" - the CTAO configuration upon the completion of its first construction phase, and "Omega" - the ultimate CTAO arrays configuration) is computed based on neutrino and gamma-ray simulations of steady sources and of flaring blazars, assuming that the neutrino events are detected with the IceCube neutrino telescope. The detection probability for CTAO is calculated for both the North and South sites, taking into account visibility constraints. We find that, under optimal observing conditions, within 30 minutes of observation, CTAO could detect the VHE gamma-ray emission associated with 2 to 3 neutrino events per year. We investigate the detectability of the blazars given either 1 or 5 hours CTAO observation windows.

Speaker: Olga Sergijenko

13:35 A Hierarchical Shock Acceleration Model for Ultra-High-Energy Cosmic Rays and Multimessenger Signatures

Accretion shocks in the large-scale structure of the universe are promising sources of ultra-high-energy cosmic rays (UHECRs). In addition to accelerating UHECRs, these shocks should produce distinct multimessenger signatures, including synchrotron radio emission, gamma rays, and neutrinos. We investigate how a hierarchical shock acceleration framework—progressing from supernova remnant shocks to galactic wind termination shocks and ultimately to cosmic structure-formation shocks—naturally explains the full cosmic ray spectrum extending beyond the ankle. Using a hydrodynamic cosmological simulation, we compute the energy processed at cluster and filamentary shocks and predict the corresponding radio synchrotron emission. We find that microgauss magnetic fields at these shocks could explain both UHECRs and the diffuse radio synchrotron background below 10 GHz. These fields may be amplified through a combination of early-Universe galactic outflows, plasma instabilities, and small-scale turbulent dynamo action. The model also predicts a correlation between UHECR anisotropy and large-scale cosmic structure, which can be tested with Auger and future radio and gamma-ray observatories. Our results motivate a multimessenger strategy to identify UHECR sources and test whether accretion shocks dominate their acceleration.

Speaker: Dr Paul Simeon (Stanford University)

13:50 Inferring properties of binary neutron star mergers from the shock breakout emission

Neutron star (NS) mergers are amongst the most promising multimessenger sources in the Universe, as demonstrated by the coincident detection of gravitational waves (GWs) with multi-wavelength electromagnetic (EM) radiation for GW170817. NS merger remnants are thought to launch relativistic jets which produce short gamma-ray bursts (sGRBs). However, the exact nature of the NS post-merger remnant is unknown: it can be a promptly formed black hole (BH), a hypermassive NS that later collapses to a BH, or a stable NS. The specific engine properties, such as the jet launching mechanism, can affect the jet evolution and their observable signatures. In this work, we investigate the propagation of jets through realistic NS merger ejecta modeled through General-Relativistic Radiation Hydrodynamic (GRRHD) simulations. We construct a semi-analytical jet+cocoon propagation model and examine the conditions under which these successfully break out from the ejecta. We calculate the EM emission associated with the shock breakout and compare several NS merger simulations with different microphysics or binary configurations with the gamma-ray observational data from GW170817. With this analysis, we infer the most favorable engine properties and nuclear microphysics for this event.

Speaker: Eduardo Mario Gutiérrez

14:05 Probing for Gamma-Ray Emission near KM3-230213A Neutrino Event with VERITAS

The recent announcement of the detection of the ultra-high-energy (UHE) neutrino event KM3-230213A by the KM3NeT telescope represents a critical opportunity to explore the origins of cosmic neutrinos and their potential gamma-ray counterparts. With an inferred neutrino energy exceeding 100 PeV, this event stands as the most energetic neutrino observed to date. The large offset from the galactic plane (~11°) and presence of several blazars with temporally-correlated multi-wavelength counterparts within the 3° localization region raises the possibility of an extragalactic origin. Additionally, the event’s apparent tension with IceCube constraints suggests that it could be transient in nature rather than cosmogenic. VERITAS conducted a targeted follow-up campaign to search for very-high-energy (VHE, >100 GeV) gamma-ray emission associated with KM3-230213A. Observations were performed in February and March 2025, using a four-point wobble strategy centered on the best-fit neutrino position, covering nearly the entire 90% confidence region. These observations probe potential hadronic gamma-ray emission from a common origin with the neutrino, placing constraints on particle-acceleration scenarios. We present the results of this search, including upper limits on VHE gamma-ray flux and their implications for possible source models of KM3-230213A.

Speaker: Connor Mooney

14:20 Latest Results from the Searches for Photons at the Highest Energies with the Pierre Auger Observatory

The Pierre Auger Observatory is the largest air-shower detector in the world, offering unparalleled exposure to photons with energies above $5 \times 10^{16}$ eV.
Since the start of data collection almost two decades ago, numerous searches for photons have been conducted using the detection systems of the Observatory.
These searches have led to the most stringent upper limits on the diffuse photon flux.
These limits place severe constraints on current models regarding the origin of cosmic rays and emphasize the significant capabilities of the Pierre Auger Observatory in the context of multimessenger astronomy at the highest energies.
This contribution provides an overview of the ongoing efforts to search for high-energy photons in the data from the Pierre Auger Observatory.
The latest results from searches for the diffuse photon flux will be presented, along with follow-up investigations for photons associated with transient events, such as gravitational wave detections.
Furthermore, future prospects will be discussed in light of the AugerPrime detector upgrade, which will enhance the sensitivity of the Observatory to photons up to the highest energies.

Speaker: Pierpaolo Savina (Gran Sasso Science Institute)

14:35 Search for GeV neutrinos from different Gamma-Ray Burst populations with IceCube

Astrophysical transients like Gamma-Ray Bursts (GRBs) have been promising candidates of neutrino source since the beginning of neutrino astronomy. Neutrinos associated with these events are yet to be observed. However, GRBs are famous for their variability, and there is the possibility that the processes inside GRBs are not fully similar over the whole population. GRBs are commonly split in two populations which are believed to be matched with differing precursors, based on duration as well as kilonova or supernova association, among other signs. Further subpopulations have also been suspected, with differences in luminosity, afterglow and jet propagation. This can indicate that the different subpopulations of GRBs can emit different neutrino fluxes. Furthermore, most searches for neutrinos associated with GRB events have focused on the TeV regime, while the lower-energy GeV neutrinos have only recently garnered more attention. In this contribution, we describe a search for GeV neutrinos from different subpopulations of GRB using the IceCube neutrino observatory. We discuss the capabilities of GeV searches with IceCube as well as methods to differentiate the different GRB populations, combining them for a better sensitivity for GRB neutrinos.

Speaker: Karlijn Kruiswijk (UCLouvain)

13:20 → 14:50 NU: highlights & analysis

13:20 Combined KM3NeT-ARCA and ANTARES searches point-like neutrino emission

Neutrino telescopes are at the forefront of high-energy astrophysics, offering unique insights into some of the most extreme and energetic phenomena in the Universe. The ANTARES detector, which operated for 16 years off the coast of Toulon (France) until 2022, has played a pioneering role in deep-sea neutrino observations. Building upon its legacy, the next-generation KM3NeT-ARCA observatory is currently under construction in the deep waters of the Mediterranean near Southern Italy, designed to push the boundaries of astrophysical neutrino detection.
ANTARES consisted of 12 vertical detection lines equipped with optical modules, each housing a 10” photomultiplier tube to capture the faint Cherenkov light from neutrino interactions in the surrounding water. In contrast, KM3NeT-ARCA will be vastly more sensitive, comprising 230 detection lines, each holding 18 optical modules, with every module integrating an array of 31 compact 3” photomultiplier tubes.
In recent years, the search for astrophysical neutrino sources has gained momentum, as their detection would provide crucial evidence of hadronic acceleration mechanisms at play in the most powerful cosmic environments. This study analyses the combined dataset from ANTARES and the available KM3NeT-ARCA observations, focusing on the detection of high-energy neutrinos from both point-like and diffuse sources.
A comprehensive catalog of about 100 point-like and extended astrophysical sources has been examined for potential neutrino emissions. This selection includes prominent γ-ray emitters, Galactic γ-ray sources with possible hadronic components (TeVCat), extragalactic AGNs with intense radio flux detected by VLBI, and the most promising candidates previously investigated by IceCube. The results of this analysis represent a significant step toward uncovering the origin of cosmic neutrinos and advancing multi-messenger astronomy.

Speaker: Barbara Caiffi (INFN e Universita Genova (IT))

13:35 The flux of electron antineutrinos from supernova SN1987A data

The neutrinos from the core collapse SN1987A are the first extrasolar neutrinos to be ever detected and have been widely studied to infer the thermodynamical and temporal features of a supernova; however their interpretation in terms of the astrophysical properties of the explosion has been giving rise to heated debates since ever. At date, models are still under construction and simulations do not always depict same things, thus the significance of the data at our disposal must be assessed as accurately as possible.
By adopting a state-of-the-art parameterized model of electron antineutrino emission, we have made some steps forward in the analysis of the available data from core collapse SN1987A taking into account the times, energies and angles of arrival of all detected events in a reliable framework which includes a finite ramp in the initial stage of the neutrino emission.
We determine the parameters of the accretion and cooling emissions and discuss their durations. The results compare well with theoretical expectations and overcome some tensions found in previous similar analyses. We estimate the delay times between the first antineutrino and the first event in the detectors. We test the agreement of the best-fit flux with the empirical temporal, energy and angular distributions, eventually finding a good compatibility with the observed data.

Speaker: Veronica Oliviero (Università di Napoli Federico II - INFN sez. Napoli)

13:50 All-flavor Time-dependent Search for Transient Neutrino Sources

Transient sources are among the preferred candidates for the sources of high-energy neutrino emission. Intriguing examples so far include blazar flares and tidal disruption events coincident with IceCube neutrinos. Here, we report the first all-flavor, all-sky time-dependent search for neutrino sources by combining IceCube throughgoing tracks, starting tracks and cascades. Throughgoing tracks provide the best sensitivity in the Northern Sky, while cascades have worse angular resolution but yield better sensitivity in the Southern Sky than tracks. The relatively new starting tracks sample has reduced contamination from atmospheric muons. This analysis takes advantage of the strengths of each of the datasets, combining them for increased statistics and obtaining the best accessible all-sky sensitivity for transient searches. In this search, we look for unbound $E^{-\gamma}$ power-law sources, as well as $E^{-2}$ sources with low and high-energy exponential cutoffs, optimizing the sensitivity for the duration of the flares.

Speaker: Jose Carpio Dumler

14:05 Search for a diffuse astrophysical neutrino flux from the Galactic Ridge with KM3NeT/ARCA

KM3NeT/ARCA is a second-generation neutrino telescope currently under construction in the Mediterranean Sea. Its capability to collect high-quality data has been recently demonstrated by the detection of an ultra-high-energy neutrino of astrophysical origin.
Located in the Northern Hemisphere with a high duty cycle, the detector has an optimal view of the Galactic Center, primarily via well-reconstructed track-like events. This study analyzes the KM3NeT/ARCA dataset acquired during the detector operation to search for an excess of neutrino events from the Galactic Ridge, defined by Galactic coordinates |b| < 2° and |l| < 30°. This region, previously investigated also using ANTARES data, is expected to exhibit a harder spectral index for cosmic ray emission compared to other areas of the Galactic plane.

Speaker: Francesco Filippini (Dipartimento di Fisica e Astronomia - Università di Bologna, INFN-Bologna, Italy)

14:20 Constraining the diffuse neutrino flux from gamma-ray burst blastwaves with the KM3-230213A ultra-high-energy event

KM3NeT/ARCA is a deep-sea Cherenkov neutrino detector located 100 km off the coast of the southern tip of Sicily, Italy. When completed, the detector will instrument around one cubic kilometre of water with photodetectors to search for energetic neutrinos of cosmic origin. On February 13th 2023, a partial configuration of KM3NeT/ARCA detected the most energetic neutrino ever observed, with an estimated energy of 220 PeV. This intriguing discovery raises questions about the origin and potential sources capable of producing neutrinos of this energy. In this talk, we will discuss lepto-hadronic interactions in gamma-ray burst blastwaves as possible production sites for neutrinos of this energy. Moreover, we will discuss how the observation of the first-ever ultra-high-energy neutrino and the corresponding ultra-high-energy diffuse neutrino flux can provide new constraints on theoretical model parameters driving the emissivity of ultra-high-energy neutrinos from a larger population of gamma-ray bursts.

Speaker: Per Myhr

14:35 Measuring the Neutrino Flux in Segments along the Galactic Plane with IceCube

Gamma-ray emission from the plane of the Milky Way is understood as partly originating from the interaction of cosmic rays with the interstellar medium. The same interaction is expected to produce a corresponding flux of neutrinos. In 2023, IceCube reported the first observation of this galactic neutrino flux, rejecting the null-hypothesis at 4.5σ. The analysis relied on spatial models – based on gamma ray observations – to model the expected neutrino emission from the galactic plane. Three signal hypotheses describing different possible spatial and energy distributions were tested, where the single free parameter in each test was the normalization of the neutrino flux.
We present an analysis that can improve the characterization of Galactic neutrino emission by dividing the galactic plane into segments in galactic longitude. An unbinned maximum-likelihood analysis is used that can fit the spectral index and the flux normalization separately in each segment. This work uses a full-sky cascade dataset and provides model-independent insight into the variation of the neutrino flux and energy distribution from different regions of the galactic plane.

Speaker: Ludwig Neste (Stockholm University/Oscar Klein Centre)

13:20 → 14:36 NU: methods for analysis

13:20 Reducing Simulation Dependence in Neutrino Telescopes with Masked Point Modeling

Machine learning techniques in neutrino physics have traditionally relied on simulated data, which provides access to ground-truth labels. However, the accuracy of these simulations and the discrepancies between simulated and real data remain significant concerns, particularly for large-scale neutrino telescopes that operate in complex natural media. In recent years, self-supervised learning has emerged as a powerful paradigm for reducing dependence on labeled datasets. Here, we present the first self-supervised training pipeline for neutrino telescopes, leveraging point cloud transformers and masked autoencoders. By shifting the majority of training to real data, this approach minimizes reliance on simulations, thereby mitigating associated systematic uncertainties. This represents a fundamental departure from previous machine learning applications in neutrino telescopes, paving the way for substantial improvements in event reconstruction and classification.

Speaker: Felix Yu

13:35 Measurement of optical water properties using stopping muons in KM3NeT/ORCA

The KM3NeT Collaboration is currently building two neutrino detectors at the bottom of the Mediterranean Sea. The KM3NeT/ARCA telescope is under construction off-shore Sicily, Italy, at a depth of about 3.5 km. The main goal of KM3NeT/ARCA is cosmic neutrino studies. KM3NeT/ORCA is being built off-shore Toulon, France, about 2.5 km below the sea surface. Its main physics objective is the determination of the neutrino mass ordering and precise oscillation parameter measurements. Optical water properties and light detection efficiency are among the main systematic uncertainties for these goals. In this work, reconstructed atmospheric muons that stop within KM3NeT/ORCA are explored in order to constrain these uncertainties. Such muons lose energy dominantly through ionisation when entering the etector sensitive volume which makes them an eligible light source for this measurement. The improved constraints on these uncertainties will result in better sensitivities in neutrino oscillation studies.

Speaker: Andrey Romanov (LPC-Caen)

13:50 Refinement of antenna response and ice properties at radio wavelengths

The now decommissioned ARIANNA experiment, which operated in Antarctica between 2014 and 2021, demonstrated that low cost, near surface, directional radio antennas can reject thermal and anthropogenic backgrounds as sufficient levels required by future arrays of similarly constructed near surface stations of 500 stations or more, while the neutrino efficiency remains above 90%. Each ARIANNA station is self contained and operated reliably at a power consumption of only 10 watts, which is low enough to permit year round eco-friendly operation in polar climates such as solar panels, and because up to half the year is without sun, wind turbines. The neutrino sensitivity was indirectly assessed by observing cosmic ray events, which produce similar radio pulse emission by their collisions in atmosphere, by identical in-situ antennas facing the upward direction. The collaboration also published a study of energy resolution, which utilizes field data and simulation of the double pulse technique known as DNR, to determined the distance to neutrino interaction. One commonly discussed method to obtain the direction of the neutrino requires the measurement of the incoming direction of the emitted radio pulse and its polarization.The ARIANNA collaboration has reported good agreement between measured and calculated polarization from a radio pulse generated lowered in a previously cored hole near the South Pole, Antarctica, between depths of 1000 m and 1700 m. The angular range of the arrival directions of the radio pulses covered in this study overlaps with most of the expected signal arrival directions from neutrino events within detectors located on the Ross Ice Shelf.

In this paper, we describe work to assess the polarization reconstruction from pulser emission at shallower depths, where upward traveling signals arrive within 30 deg of the local horizontal direction. The shallower pulser depths corresponds to arrival directions that cover a majority of neutrino interactions within detectors at high elevation polar locations. Two issues are studied: (1) the simulated in situ antenna response for large arrivals angles relative are not proven to be reliable, and must be calibrated or empirically assessed; (2) radio signals will reflect off the snow-air surface an enter the antenna through the back lobe, and the antenna response is also poorly known. The predicted polarization is compared to the measured value using archival pulser data collected in a follow up study.

Speaker: Steve Barwick

14:05 Neutrino Event Properties and Reconstruction with the Radar Echo Telescope

The Radar Echo Telescope (RET) collaboration aims to detect the cosmic neutrino flux at the highest energies through the radar echo method. Radar is a detection technique that allows for determining the position, speed and direction of a macroscopic object using radio waves. In-ice neutrino interactions leave a dense ionization trail that can be detected using radar. We will discuss the very rich phenomenology of the expected radar signal and its features, with an emphasis on reconstructing the neutrino properties such as arrival direction and energy.

Speaker: Jannes Loonen (Vrije Universiteit Brussel)

14:20 Improving track reconstruction in IceCube with neural-network based photon transport PDFs

The IceCube Neutrino Observatory is a neutrino detector located at the South Pole consisting of a three-dimensional array of optical sensors embedded deep within the Antarctic ice. It records the Cherenkov radiation produced by charged particles that are generated when neutrinos interact in the ice. The trajectory of the original neutrino can be inferred by analyzing the spatial and temporal distribution of the observed Cherenkov light. Muon tracks from high-energy, charged-current muon neutrino interactions are of particular interest for neutrino astronomy due to their sub-degree angular resolution. The current state-of-the-art reconstruction method, used to analyze IceCube’s high-statistics samples of these events, assumes that Cherenkov light is emitted uniformly along the muon trajectory. It relies on knowing the corresponding photon arrival time distributions for each event and sensor combination. These PDFs were extracted from dated, computationally expensive detector simulations using interpolation techniques that do not scale to the current complexity of the problem.
Here, we present a machine-learning approach, specifically a mixture density network, to extract new state-of-the-art photon arrival time distributions with an improved ice model. Building on the improved correctness of the PDFs and including information about the muon energy loss pattern, we devise methods to mitigate the impact of stochastic energy losses on the angular reconstruction. We compare the performance (e.g., angular resolution and coverage of angular uncertainties) of the new methods to the current standard by leveraging a novel GPU-accelerated JAX implementation of the reconstruction method that greatly reduces the runtime of the algorithm.

Speaker: Matti Jansson

14:50 → 15:20 Coffee

15:20 → 16:50 CRD: transport

15:20 The Role of Acoustic Instability in Cosmic-Ray Self-Confinement

Over the past decades, there has been growing observational and theoretical evidence that cosmic-ray-induced instabilities play an important role in both acceleration and transport of cosmic rays (CRs). For instance, the efficient acceleration of charged particles in supernova remnant shocks requires rapidly growing instabilities, so much so that none of the proposed processes seem sufficient to warrant acceleration to PeV energies. At the same time, there has been growing evidence of suppressed diffusivity around pulsar wind nebulae, in the form of the so-called TeV halos, which also seems to suggest that something peculiar is being caused by the particles escaping these sources.

In this work, we investigate whether an acoustic instability triggered by the presence of a CR pressure gradient can lead to significant self-confinement of charged particles in the vicinity of shocks, as well as of CRs escaping pulsar wind nebulae surrounded by a bow shock. We validate the expected growth rate and diffusion coefficient suppression induced by such instability using magnetohydrodynamic (MHD) and MHD + particle-in-cell simulations.

Speaker: Dr Antonio Capanema (Gran Sasso Science Institute)

15:35 Non-linear transport of cosmic rays around supernova remnants: insights from particle-in-cell simulations

Cosmic rays can excite magnetic turbulence via streaming instability as they escape from their sources. The self-generated turbulence is expected to give rise to relatively smaller cosmic-ray diffusion coefficients around these sources than typically inferred for large-scale Galactic transport. In fact, gamma-ray observations from various types of sources including pulsars, stellar clusters and supernova remnants seem to suggest the presence of such a low-diffusion zone. Modelling this phenomenon, however, often relies on simplified assumptions regarding properties of self-generated turbulence. In particular, the transport of cosmic-ray perpendicular to the mean magnetic field is often neglected such that the problem can be treated in a 1D geometry and, more importantly, the resonant condition is enforced such that cosmic rays of a particular energy interact only with turbulence of a particular scale. The aim of this work is to study cosmic-ray escape by means of magneto-hydrodynamic particle-in-cell (MHD PIC) simulations which allow us to relax some of the above-mentioned assumptions and better probe the effect of self-generated turbulence from particles of different energies on both the perpendicular and parallel diffusion coefficients around sources. To this end, we perform MHD PIC simulations of two cosmic-ray populations with different energies, where the high-energy population is injected before the low-energy one in an extended region to mimic the case of supernova remnants. In this talk, we will present some of our preliminary results concerning the turbulence power spectra and the diffusion coefficients of the low-energy population in cases with and without the high-energy one. Observational consequences of our findings will also be discussed.

Speaker: Vo Hong Minh Phan (LUX, Sorbonne University)

15:50 Every Nearby Pulsar is Surrounded by Inhibited Diffusion

The electron + positron cosmic-ray flux recently released by the H.E.S.S. telescope shows a remarkable behaviour: It breaks at around 1 TeV and falls off quickly, following a smooth powerlaw. This is in tension with simple pulsar models, which predict a much harder electron spectrum at tens of TeV. However, in two-zone diffusion models, propagation of high-energy electrons is inhibited in a region around the pulsar (consistent with pulsar wind nebulae and TeV halos), causing the spectral hardening to soften the high-energy spectrum in agreement with observations. We find that there are a tens of known pulsars that would individually overproduce the H.E.S.S. TeV flux, allowing us to conclude that every nearby pulsar must be surrounded by a zone of inhibited diffusion.

Speaker: Isabelle John

16:05 Kinetic simulations of electron-positron induced streaming instability in the context of gamma-ray halos around pulsars

We conduct 1D particle-in-cell (PIC) and particle-in-cell-magnetohydrodynamic simulations of a hot superAlfvénic electron-positron (ee) beam pervading a cold electron-proton (ep) background. We investigate the growth and saturation of the resonant streaming instability triggered by the ee beam. We confirm quasi-linear growth rates and a saturated amplitude of waves to be consistent with a momentum exchange criterion between the decelerating beam and growing magnetic waves. We discuss how these results transpose to the case of ee confinement around evolved pulsars showing a gamma-ray halos like GEMINGA or Monogem.

Speaker: Alexandre MARCOWITH (Laboratoire Univers Particle Montpellier)

16:20 Cosmic-Ray Driven Buoyancy in the Galactic Halo

At large scales (> 1 pc), low energy (~few GeV) cosmic rays can be treated as a fluid. In this limit, there are three possible transport mechanisms: (1) advection with the background plasma, (2) streaming at the Alfven speed, and (3) diffusion. Whichever process is dominant sets the effective equation of state $(P_c \propto \rho^{\gamma_c})$ of the cosmic-ray fluid. While transport is likely diffusive in the galactic disk, the streaming and advective transport are dominant in the galactic halo. We examine how a change in the cosmic-ray fluid's equation of state dues to this change in transport affects the buoyancy of a gas parcel. This model illustrates how an initially buoyantly unstable parcel in the galactic disk (because the cosmic-ray fluid has $\gamma_c \sim 0$ in the diffusive limit) could become buoyantly stable in the galactic halo. This process likely impacts thermally stable gas with temperatures of $T\sim 10^{4} \mathrm{K}$, helping to explain how cold gas clouds could get stuck floating in the galactic halo.

Speaker: Roark Habegger

16:35 Cosmic Ray Heating in the Early Universe: Joule Heating by Return Currents and its Impact on the Thermal Evolution of the Intergalactic Medium at Redshift around 10

Cosmic rays (CRs) play crucial roles in various astrophysical environments in the present Universe. They can penetrate deep into dense molecular clouds, altering their ionization degree and influencing star formation. Additionally, CRs exert pressure on galactic gas and contribute to driving galactic winds. However, their role in the early Universe remains poorly understood. Since CRs are expected to be accelerated in supernova remnants of the first stars, they are likely to affect the galactic and intergalactic environments in the early Universe.
In this study, we propose a novel CR heating mechanism and investigate its impact on the intergalactic medium (IGM) at redshift $z \sim 10$. As CRs escape from a galaxy, they carry an electric current, which induces a return current of thermal electrons to maintain current neutrality. Since collisions between thermal electrons and thermal ions are not negligible on cosmological timescales, the return current induces Joule heating. We also consider electron-neutral collisions and evaluate the heating rate by this mechanism. Furthermore, we compare our proposed mechanism with other CR heating processes and the heating by X-rays, which is conventionally considered the dominant heating source of the IGM at $z \sim 10$. By solving the evolution equations of temperature and ionization degree simultaneously, we predict the IGM temperature achieved by these heating mechanisms. Our results suggest that the proposed CR heating mechanism could be a dominant process in determining the IGM temperature at $z \sim 10$. Finally, we discuss the observability of CR heating signatures in future 21-cm line radio observations.

Speaker: Shota Yokoyama (Chiba University)

15:20 → 16:50 CRI: laboratory

15:20 First Deuteron Production Measurement in Proton-Proton Interactions at SPS energies by NA61/SHINE

The detection of cosmic-ray antinuclei holds the potential to be a groundbreaking method for identifying signatures of dark matter. The dominant background for cosmic antinuclei arises from interactions of cosmic-ray protons with interstellar hydrogen gas. However, prevalent (anti)nuclei formation models—the thermal and coalescence models—are based on different underlying physics. A deeper understanding of (anti)nuclei production mechanisms is essential to evaluate the background production and drives the ongoing effort to analyze high-statistics data from fixed-target experiments. Improving our understanding of deuteron production is a critical first step toward accurately modeling cosmic antideuteron in astrophysical processes. Antinuclei production models typically also require antiproton production cross sections as input, underscoring the importance of precise antiproton measurements as well.

NA61/SHINE has performed the first measurement of deuteron production in proton–proton interactions at 158  GeV/c (sqrt(s) = 17.3 GeV). In addition, updated proton and antiproton production yields will also be presented. These exhibit a threefold reduction in statistical uncertainties and extend the phase-space coverage in both rapidity and transverse momentum compared to previous measurements. These results will advance our understanding of proton–proton interactions at cosmic-rays energies.

Speaker: Anirvan Shukla (University of Hawai'i at Manoa (US))

15:35 Antiproton production cross section for indirect dark matter search from the AMBER experiment

One of the indirect detection method of dark matter (DM) is based on the search of the products of DM annihilation or decay. They should appear as distortions in the gamma rays spectra and in the rare Cosmic Ray (CR) components, like antiprotons, positrons and antideuterons, on top of the standard astrophysical production. In particular, the antiprotons in the Galaxy are mainly of secondary origin, produced by the scattering of cosmic proton and helium nuclei off the hydrogen and helium in the interstellar medium (ISM). In order to obtain a significant sensitivity to DM signals, accurate measurements of the antiproton production cross section in p+p and p+He collisions are crucial. The AMBER experiment at CERN collected in 2023 the first data ever in p+He collision at a center of mass energy from 10 to 21 GeV. Preliminary results will be shown in this talk. The 2024 AMBER program with proton beam on liquid hydrogen and deuterium targets will be also presented. This new measurement is going to significantly reduce the uncertainty on the extrapolation of the antineutron decays contribution to the antiproton production in the Galaxy.

Speaker: Davide Giordano (INFN Torino)

15:50 Cosmic ray antihelium in the Galaxy

The creation of anti-nuclei in the Galaxy has been discussed as a possible signal of exotic production mechanisms such as primordial black hole evaporation or dark matter decay/annihilation in addition to the more conventional production from cosmic-ray interactions. Tentative observations of cosmic-ray andideuteron and antihelium by the AMS-02 collaboration have re-energized the quest to use antinuclei to search for physics beyond the standard model.

In this talk, we show state-of-art predictions of the antinuclei flux from both cosmic-ray interactions with the interstellar medium and standard dark matter annihilation models from combined fits to high-precision antiproton data as well as cosmic-ray nuclei measurements. Astrophysical mechanisms can explain the amount of antideuteron events detected by AMS-02, while their antihelium production lies far below the sensitivity of this experiment. In turn, standard dark matter models could potentially produce the detected antideuteron and antihelium-3 events, but the production of any detectable antihelium-4 flux would require exotic physics. We also present prospects for detection of these antinuclei by future detectors, such as GAPs and ALADInO.

Speaker: Pedro De la Torre Luque (Institute of theoretical physics (IFT-UAM))

16:05 The PANDORA Project: Investigating Photonuclear Reactions in Light Nuclei.

The PANDORA (Photo-Absorption of Nuclei and Decay Observation for Reactions in Astrophysics) project focuses on the experimental and theoretical study of photo-nuclear reactions involving light nuclei with masses below A = 60. This research is particularly relevant to the study of ultra-high-energy cosmic rays (UHECRs), where energy and mass loss is primarily driven by the electromagnetic interaction between nuclei and the cosmic microwave background via the isovector giant dipole resonance (IVGDR). These interactions also occur to a lesser extent between the infrared/optical/ultraviolet light and the UHECR but to a lesser extent. Current propagation models and reaction calculations are hindered by the scarcity of reliable experimental data for key nuclei. To address this, PANDORA utilizes both virtual photon experiments at iThemba LABS and RCNP, as well as real photon experiments at ELI-NP, to extract essential information, including the cross-section of the IVGDR, E1 strength, and branching ratios for particle decay in light nuclei. The first experiment within the PANDORA project was conducted at RCNP in late 2023. This talk will focus on the analysis of $^{12}$C and $^{13}$C photo absorbtion and charged particle decay data. This experiment employed the Grand Raiden spectrometer in conjunction with SAKRA, a backward-angle silicon detector array for charged particle detection, and SCYLLA, a LaBr3 detector array. The results from these measurements and their implications for loss length calculations in UHECR propagation will be discussed.

This work is based on the research supported in part by the National Research Foundation (NRF) of South Africa grant number 118846, the Romanian Ministry of Research, Innovation and Digitization, CNCS - UEFISCDI, project number PN-III-P4-PCE-2021-0595, within PNCDI III, and the Japan-South Africa Bilateral Funding from JSPS
with a grant number of JPJSBP 120216502 and from NRF with grant number 132993, the National Research Foundation of South Africa through Grants No. 129411, and 118846 and the SARCHI grant number 180529336567.

Speaker: Jacob Bekker (University of the Witwatersrand, iThemba LABS, South Africa)

16:20 Measurements of hadronic interactions at LHCb and their impact on photon/neutrino emission in UHECR sources

Out in the universe, when ultra-high energy charged cosmic rays (UHECR) propagate from their source and/or acceleration site, they may interact with the environment (gas), producing high-energy gamma rays and neutrinos. One of the main uncertainties in the prediction of the flux of gamma rays and neutrinos from such UHECR interactions is due to the uncertainties in the modeling of hadronic interactions.
Back here at Earth, the LHCb experiment at CERN employs a general-purpose forward spectrometer designed to study heavy flavour physics at the LHC. The acceptance of the spectrometer covers the pseudorapidity range 2 < η < 5 and provides full tracking and particle identification down to very small transverse momenta. This makes LHCb also ideal to study hadronic interactions similar to those undergone by UHECRs.
The modeling of different astrophysical source scenarios involves the transport of CRs through magnetic fields, generating secondaries from CR interactions in the local environment and tracking these interaction products through the universe to Earth. All these processes are implemented in CRPropa. Since recently it also provides an interface to the general-purpose hadronic event generators.
In this contribution we summarize measurements of hadronic particle production done by LHCb and use them to evaluate the performance of the event generators employed in CRpropa. Based on these comparisons we determine which measurements could be performed in LHCb in the future to reduce the uncertainty in the hadronic interaction models and provide better constraints on the modeling of astrophysical sources and transport.

Speaker: Lars Kolk (Technische Universitaet Dortmund (DE))

16:35 Updates on Antiproton and Antideuteron Production Cross Section in Cosmic Rays Collision.

Antiprotons and antideuterons in cosmic rays (CRs) are studied to search for potential signals of exotic physics—such as dark matter annihilation—beyond the expected astrophysical background produced by collisions between primary CRs and the interstellar medium.

In particular, it has been argued that the production of secondary antideuterons should be suppressed at kinetic energies below a few GeV/n due to interaction kinematics. Therefore, any observation of antideuterons in that energy range would be strong evidence for new physics.

However, predictions from secondary production models are limited by current uncertainties in antiproton production cross sections, which are on the order of 10–15%. Additionally, models for antideuteron cross sections vary by an order of magnitude at kinetic energies below 10 GeV/nucleon.

In this contribution, a novel analytic model for the production cross sections of antiprotons and antideuterons, based on the latest experimental data from accelerators, will be discussed. Preliminary results for the predicted antiproton and antideuteron spectra, obtained using the cosmic ray propagation model GALPROP-HelMod with updated secondary production cross sections, will also be presented.

Speaker: Francesco D'Angelo (Universita e INFN, Bologna (IT))

15:20 → 16:50 GA: GRBs, FRBs, transients

15:20 TeV emission from Gamma-Ray Bursts: Signatures of Inverse Compton Scattering induced from Kilonova-jet Interactions

The fireball model has been widely used to explain the spectral energy distribution and light curves of gamma-ray bursts (GRBs) during the afterglow phase. According to this model, particles are accelerated in external shocks, resulting in photon emission via synchrotron radiation and synchrotron self-Compton (SSC) processes. However, this framework does not fully account for all observed cases. Notably, the GeV excess detected in GRB 211211A has been attributed to external inverse-Compton (EIC) interactions, where optical kilonova photons are upscattered by electrons accelerated in the forward shock of a weaker secondary jet. Observations with the High Altitude Water Cherenkov (HAWC) gamma-ray observatory reveled photons spatially coincident with a few GRBs, detected at timescales consistent with the expected kilonova emission peak. In this work, we argue that the detected VHE photons indeed originate from these GRBs, the SSC mechanism in both forward and reverse shocks fails to account for them. Instead, we propose that these photons result from inverse-Compton scattering of kilonova photons by electrons within the reverse shock.

Speaker: Sara Fraija (IA-UNAM)

15:35 Time and energy resolved detection of gamma-ray transients with the High-Energy Particle Detectors onboard the CSES satellites

The High-Energy Particle Detectors (HEPDs) onboard the China Seismo-Electromagnetic Satellite (CSES) mission are designed to study charged particle fluxes in space. The first-generation instrument, HEPD-01 on CSES-01, was originally conceived to measure low-energy electrons and protons but has also demonstrated the ability to detect transient phenomena such as Gamma-Ray Bursts (GRBs). By analyzing anomalous fluctuations in the rate meters of its trigger system, HEPD-01 successfully identified several GRB events, which were confirmed by other independent space-borne instruments. These observations were recently compiled into a dedicated GRB catalog providing information in the energy range 0.3–50MeV scarcely covered by other instruments.

Building on these results, the next-generation HEPD-02 on CSES-02 introduces significant improvements to enhance GRB detection. The new instrument features an expanded LYSO calorimeter, extending the energy range for fully contained photon events, and a dedicated onboard trigger algorithm capable of autonomously registering transient signals with millisecond resolution. The combined use of the LYSO calorimeter and the plastic scintillators of the Range Detector (RAN) allows for a more detailed analysis of event topologies, improving gamma-ray interaction reconstruction. In particular, HEPD-02 will be sensitive to gamma photons starting at approximately 0.5 MeV, with a peak effective area of $~$130 cm$^2$ near 30 MeV.

In this contribution, we present the GRB detection methodology and key findings from HEPD-01, highlighting its contributions to the field and the ongoing efforts to refine its detection capabilities. We will also discuss how these results have guided the development of HEPD-02, detailing the upgrades incorporated in this second-generation instrument. Furthermore, we will showcase the architectural design of HEPD-02 and its custom-developed trigger algorithm for transient detection, illustrating how these advancements enhance the detector’s performance in monitoring GRBs.

Speaker: Riccardo Nicolaidis (Universita degli Studi di Trento and INFN (IT))

15:50 GeV Gamma-Ray Detection from Intense GRB 240529A During the Afterglow’s Shallow Decay Phase

X-ray light curves of gamma-ray burst (GRB) afterglows exhibit various features, with the shallow
decay phase being particularly puzzling. While some studies report absence of the X-ray shallow decay
for hyper-energetic GRBs, recently discovered GRB 240529A shows a clear shallow decay phase with
an isotropic gamma-ray energy of $2.2\times10^{54}$ erg, making it a highly unusual case compared to
typical GRBs.
In order to investigate the physical mechanism of the shallow decay, we perform the
Fermi -LAT analysis of GRB 240529A along with Swift-XRT analysis. We find no jet break feature
in the X-ray light curve and then give the lower bound of the collimation-corrected jet
energy of >$10^{52}$ erg, which is close to the maximum rotational energy of a magnetar. Our
LAT data analysis reveals GeV emission with a statistical significance of 4.5σ during the shallow decay
phase, which is the first time for hyper-energetic GRBs with a typical shallow decay phase.
The GeV to keV flux ratio is calculated to be $4.2\pm2.3$. Together with X-ray spectral index,
this indicates an inverse Compton origin of the GeV emission. Multiwavelength modeling
based on time-dependent simulations tested two promising models, the energy injection and wind
models. While the energy injection model shows a tension with LAT data, both models can explain the X-ray and GeV data.
We present our results along with the future prospects of the current or next generation gamma-ray telescopes for distinguishing between the shallow decay models.

Speaker: Mr Kenta Terauchi (Kyoto University)

16:05 Astrophysical Processes Behind the GeV Component in Early GRB Afterglows Through Multi-Wavelength Observations

The early X-ray afterglows of Gamma-Ray Bursts (GRBs), observed with the Swift X-ray Telescope (XRT; 0.3–10 keV) onboard the Neil Gehrels Swift Observatory, have revealed distinct temporal features beyond those predicted by the standard forward shock afterglow model. Components in the XRT light curve, such as steep decay, flares, and plateaus, suggest more complex afterglow physics. These observations highlight the need for a multi-wavelength, systematic study of the early afterglow’s temporal and spectral evolution.
In this study, we analyzed GRB afterglows across a wide energy range, from 0.3 keV to 100 GeV, using data from Swift/XRT, Swift/BAT (15–150 keV), and the Fermi Large Area Telescope (LAT; 30 MeV–300 GeV). Our sample includes GRBs with significant high-energy gamma-ray emissions. Our analysis reveals that the broad-band GRB spectral evolution exhibits double-peaked spectral energy distributions. We discuss the implications for the microphysics of X-ray and GeV emission production sites and the underlying forward shock in the synchrotron self-Compton scenario.
These results also emphasize the importance of very high-energy (VHE; >100 GeV) gamma-ray observations in understanding the GRB emission mechanisms behind these anomalies and determining whether VHE GRBs are unique. I will also briefly discuss the prospects of these observations through upcoming facilities, such as the Cherenkov Telescope Array Observatory (CTAO), offering a more complete picture of the spectral evolution of GRBs. By integrating multi-wavelength datasets and focusing on the VHE regime, our research contributes to the broader effort of understanding the complex physics of GRBs.

Speaker: Pawan Tiwari

16:20 Dissecting the Radiative Puzzle of VHE GRBs: Insights from Multi-Wavelength Modeling

The recent detection of very high-energy (VHE, $>$ 100 GeV) gamma-ray emission from gamma-ray bursts (GRBs) has provided new insights into afterglow physics. Understanding the temporal and spectral evolution of VHE GRBs requires detailed modeling and multi-wavelength observations spanning radio to VHE. The afterglow emission primarily consists of synchrotron radiation from forward and reverse shocks, synchrotron self-Compton (SSC) emission, and external Compton (EC) emission. We conducted a detailed multi-wavelength modeling of six long-duration VHE GRBs - GRB 180720B, GRB 190114C, GRB 190829A, GRB 201216C, GRB 210619B, and GRB 221009A; using the NAIMA code, which employs radiative models and Markov chain Monte Carlo (MCMC) techniques. Our analysis constrains key parameters governing the emission and surrounding environments of these GRBs. The results indicate that synchrotron self-Compton (SSC) is the dominant VHE emission mechanism, with negligible contribution from external Compton (EC). Most VHE GRBs are well described by a forward shock model in a spherical jet configuration, except for GRB 221009A, which requires additional considerations. Additionally, we find that VHE GRBs tend to occur in environments with lower magnetic fields and higher ambient medium densities. Interestingly, VHE GRBs lie outside the 3-$\sigma$ region of the $E_{k,\rm iso}$ - $\epsilon_B$ correlation observed in other high-energy GRBs. These findings provide crucial constraints on VHE GRB emission mechanisms and serve as a benchmark for future observations and theoretical studies in the era of CTA and next-generation gamma-ray observatories.

Speaker: Dr ankur ghosh (University of Johannesburg)

16:35 Exploring GRB Afterglows in the TeV Era: New Diagnostics of Particle Acceleration

The TeV gamma-ray band is essential for probing the most extreme particle acceleration processes in the Universe. The recent detections of gamma-ray bursts (GRBs) at these energies offer an incredible opportunity to investigate the origins of such transient events in an unprecedented way. In this presentation, we analyze the afterglows of these GRBs by modeling their synchrotron and inverse Compton emission within an optimized relativistic fireball framework. By comparing observational data with theoretical predictions, we constrain key model parameters and track their temporal evolution. The comparison of different TeV-detected GRBs reveals an intriguing variety among them, potentially reflecting differences in the particle acceleration processes that have to be very fast and able to accelerate to large energies. We discuss how late-time afterglow observations of X-ray and GeV-TeV emissions are crucial for providing diagnostics into the physics of GRBs. At this scope, we also present the most updated results of the AGILE telescope, which support our interpretation. Finally, we highlight theoretical predictions for future TeV observations and their implications for understanding these extreme cosmic explosions.

Speaker: Luca Foffano (INAF Rome (IAPS))

15:20 → 16:50 GA: galactic diffuse emission

15:20 Dissecting the Diffuse Gamma-Ray Emission of the Galaxy with the HAWC Observatory

Galactic diffuse gamma-ray emission is the radiation produced by the interaction of high-energy cosmic rays propagating through the Milky Way with the interstellar gas and radiation fields. Its measurement allows for crucial insights into the acceleration and transport of cosmic rays throughout our Galaxy.

Here, we present a new analysis of the TeV Galactic diffuse gamma-ray emission using 8 years of HAWC data. This data was processed with the updated Pass 5 processing, enhancing the sensitivity and resolution of the instrument. For the analysis, we make use of Gammapy, an open-source package for gamma-ray astronomy, and recent models of the Galactic diffuse emission at TeV energies.

After subtracting the emission from sources using an algorithm akin to that developed for the foreseen CTAO Galactic plane survey, we find significant remaining emission throughout the galactic plane. We show the latitudinal and longitudinal flux and emissivity profiles of the emission in multiple parts of the galaxy and compare to existing models. We find significant emission beyond 3 degree latitude, consistent in shape with the prediction for the interaction of cosmic rays with the interstellar gas.

We also demonstrate that our results are consistent with recent LHAASO results when equivalent analysis methods are used.

Finally, we discuss various systematic uncertainties related to, among others, the source contamination of the measured diffuse emission and the anisotropy in the arrival direction of background cosmic rays.

Speaker: Georg Schwefer (Max-Planck-Institut für Kernphysik)

15:35 Do the LHAASO Galactic diffuse emission data require a contribution from unresolved sources?

Recently, the LHAASO collaboration measured the diffuse gamma-ray emission in the energy range, $10-10^3$ TeV, after masking the contribution of known sources.
The measurement is 2–3 times higher than the gamma-ray signal expected from the hadronic interactions of diffuse cosmic rays with the interstellar medium, suggesting a possible contribution from unresolved sources.
However, estimates of the diffuse emission are affected by large uncertainties that must be taken into account.
We calculate the hadronic gamma-ray diffuse emission while incorporating uncertainties in the Galactic disk's gas content, the energy and spatial distribution of cosmic rays, and the hadronic interaction cross-section.
We show that the LHAASO data above $\sim 30$ TeV are consistent with the gamma-ray diffuse emission model when all these uncertainties are considered.
This suggests that, given the current data in this energy range, there is no need to invoke a cosmic ray spectral variation toward the Galactic center or a dominant contribution from unresolved sources.

Speaker: Vittoria Vecchiotti

15:50 The cosmic-ray sea explains the diffuse Galactic gamma-ray and neutrino emission from GeV to PeV

The LHAASO collaboration has recently released the spectrum and the angular distribution of the gamma-ray Galactic diffuse emission from 1 TeV to 1 PeV measured with the
Kilometer-2 Array (KM2A) and Water Cherenkov Detector Array (WCDA). We show that those data are in remarkably good agreement with a set of pre-existing models that assume the emission to be produced by the Galactic population of cosmic rays if its local spectrum traces that measured by CALET, DAMPE as well as KASCADE at higher energies. No extra-components besides the CR sea is needed to explain LHAASO results. Accounting for unresolved sources, we consistently reproduce also a wide set of gamma-ray data at lower energy. Spatial dependent CR transport models, although not required to reproduce LHAASO results, are in better agreement with them respect to conventional ones and needed to consistently reproduce Fermi-LAT and neutrino data. In fact, we also compute the associated Galactic neutrino diffuse emission finding that the contribution from sources cannot be dominant and showing that spatial-dependent propagation models closely match the ANTARES and IceCube best fits for the Galactic Center Ridge and the Galactic Plane emissions.

Based on astro-ph/2502.18268

Speaker: Dario Grasso

16:05 Measurement of diffuse gamma-ray emission based on source-deduction method at Galactic plane by LHAASO

The diffuse Galactic gamma-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a crucial probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. Using the source deduction method and the latest data from WCDA and KM2A, we have preliminarily measured this emission and present the energy spectra of diffuse emission in the Inner Galaxy region ( 15°< l <125°, |b| < 5°) and the Outer Galaxy region (125°< l < 235°, |b| < 5°). Additionally, we found that the spatial distribution of the diffuse emission deviates from the Planck Dust map, suggesting distinct astrophysical origins. These findings offer valuable insights into the properties of diffuse gamma-ray emissions and highlight the need for refined methodologies to better understand the underlying astrophysical processes.

Speaker: Rui Zhang (PMO)

16:20 A new self-consistent model for the VHE Galactic gamma-ray and neutrino emissions

In this work, we present the first example of a self-consistent 3D modeling of the VHE (>100TeV) cosmic ray (CR) distribution in our Galaxy, by injecting CRs at individual discrete transient sources in the Galactic disc, and propagating them from first principles by integrating their trajectories in models of the Galactic magnetic field. We then calculate the resulting VHE secondary gamma-rays and neutrinos from these CR distributions. Our model predicts in a self-consistent way the number of visible point gamma-ray sources, extended gamma-ray sources and the diffuse gamma-ray emission from our Galaxy. We find that the VHE diffuse Galactic gamma-ray emission is very clumpy at >~ 400 TeV, as observed by AS-gamma and LHAASO experiments. We then compare our predictions for the number of detectable hadronic and leptonic gamma-ray sources to the existing gamma-ray data from LHAASO. We show how comparing our new model predictions to such observations allows to constrain important unknown astrophysical parameters, such as the rate of PeVatrons in our Galaxy.

References:
Giacinti, Koldobskiy & Semikoz, In prep. (2025)
Giacinti & Semikoz, "Model of Cosmic Ray Propagation in the Milky Way at the Knee" (2023), arXiv:2305.10251

Speaker: Gwenael Giacinti

16:35 Comic-Ray Source Grammage Dominates The Diffuse Gamma-Ray Sky

Recent secondary-over-primary cosmic-ray (CR) ratio measurements by DAMPE and CALET show a hint of a flattening above ( \sim) TV rigidities. It is plausible - and theoretically well-motivated - that CRs accumulate additional grammage inside the source environment leading to a constant grammage in addition to the Galactic one. In this contribution, we explore this scenario, quantifying the contribution of these cocoon regions onto the secondary diffuse emissions such as gamma-rays and neutrinos. Interestingly, we find that, assuming a source grammage of ~ 0.4 gr/cm^2, compatible with the grammage accumulated by CRs in the downstream regions of Supernova Remnant shocks, and fitted against high-energy B/C measurements, the corresponding gamma-ray emission must substantially contribute to the diffuse gamma-ray flux providing a natural explanation of the gamma-ray hardening observed in the inner Galaxy. Our results may also additionally reproduce the recently published TeV-PeV gamma-ray measurements from the LHAASO and Tibet observations. We also discuss the implications of our calculation for the neutrino fluxes in light of the recent Galactic neutrino flux measured by the IceCube collaboration.

Speaker: Antonio Ambrosone (Gran Sasso Science Institute)

15:20 → 16:50 GWMS

15:20 Constraints on the Population of Common Sources of Gravitational Waves and High-Energy Neutrinos with IceCube During the Third Observing Run of the LIGO and Virgo Detectors

The discovery of joint sources of high-energy neutrinos and gravitational waves has been a primary target for the LIGO, Virgo, KAGRA, and IceCube observatories. The joint detection of high-energy neutrinos and gravitational waves would provide insight into cosmic processes, such as progenitor dynamics and outflows. The joint detection of multiple cosmic messengers can also elevate the significance of the observation when some or all of the constituent messengers are sub-threshold, not significant enough to declare their detection individually. Leveraging data from the LIGO, Virgo, and IceCube observatories, we conducted an archival investigation of sub-threshold multi-messenger events. Complementing previous analyses, we used minimal assumptions to search for common sources of sub-threshold gravitational-wave and high-energy neutrino candidates during the third observing run (O3) of the Advanced LIGO and Advanced Virgo detectors. Our search did not identify significant joint sources. We therefore derive constraints on the rate density of joint sources for each compact binary merger population as a function of the energy emitted in neutrinos. Only a fraction of the gravitational-wave sources emit neutrinos, if the neutrino emission is isotropic and has high bolometric energy ($> 10^{52}$ to $10^{54}$ erg).

Speaker: Doğa Veske

15:35 J1048+7143: Signatures of a Supermassive Binary Black Hole Close to Merger?

The blazar J1048+7143 (a.k.a. J1044+71) is a promising candidate for harboring a supermassive binary black hole (SMBBH) inspiral on the verge of merging. Its gamma-ray, optical, infrared and radio light curves show consistent quasi-periodic oscillations (QPOs) with a period of years. The flares in gamma rays, optical and infrared consist each of two subflares, while in radio, the emission follows a Gaussian-like structure.

Here, we show that the spin-orbit coupling of the leading jet in a SMBBH at the center leads to jet precession, which produces the observed flaring signatures. Using our jet precession model, we successfully predicted the timing of the last flare observed between 2022 and 2024, whereas a spine-sheath model of the jet explains the different signature in radio compared to the other wavelengths. In this contribution we present the complete multi-wavelength dataset in context of our model that we use to constrain the mass ratio on the SMBBH, allowing a prediction of the merger time, which will happen in 20-40 years. In addition, we model the characteristic strain of its expected gravitational wave emission until the time of the merger.

Speaker: Ilja Jaroschewski (Université Paris-Saclay (FR))

15:50 Crystal Eye: an instrument with a wide view of the MeV sky to study the astrophysical photons

Crystal Eye is a new concept of space-based all sky monitor for the observation of 10 keV - 30 MeV photons exploiting a novel detection technique, which foresees enhanced localization capability and functionality in an unprecedented energy range with respect to the current instruments. This is now possible, thanks to the use of new materials (scintillator crystals) and sensors (like Silicon Photo Multiplier). The primary scientific goal is the detection of the electromagnetic signal of extreme phenomena in the Universe. In order to enhance their study with different messengers to get the context as much as possible, the satellite will provide an alert to both space and ground based experiments. The full scale design of the detector has been optimized and the engineering qualification model is going to be realized at this stage. Furthermore, a scaled prototype made of three full size pixels is being realized to fly aboard the Space Rider (ESA) on a LEO orbit for a tentative life time of two months in 2027, with the aim to characterize the background at the orbit and verify the technology for space use. We present here the instrumental setup and calculation of its sensitivity and performances using Monte Carlo simulation of the full detector configuration in the speculative working environment and prototype tests.

Speaker: Ritabrata Sarkar (Gran Sasso Science Institute)

16:05 Multi-Messenger Search for Neutrino and Gravitational-Wave Emissions from Binary Black Holes Near Active Galactic Nuclei

Binary black holes (BBHs) in the vicinity of Active Galactic Nuclei (AGNs) are particularly interesting systems from both a cosmological and astrophysical point of view. Matter and radiation fields within the dense AGN environment could produce electromagnetic and neutrino emission in addition to gravitational waves (GWs). Moreover, interactions between BBHs and AGN accretion disks are expected to influence BBH formation channels and merger rates. Understanding these sources could help explain the unexpectedly high BBH masses observed through GWs by the LIGO-Virgo-KAGRA collaborations. We present a search for coincident gravitational-wave and neutrino emission from AGNs. Our new innovative approach combines information from gravitational-wave data, neutrino observations, and AGN optical catalogs to increase the chances of identifying potential sources and studying their properties. We assess the sensitivity of the search using subthreshold gravitational-wave candidates from LIGO-Virgo-KAGRA data and neutrino event candidates from public IceCube Neutrino Observatory data. A confident detection of such an event would mark a breakthrough in multi-messenger astronomy.

Speaker: Leonardo Ricca

16:20 TELAMON: Constraining the Physics of Very-High-Energy Emission in Blazars through High-Frequency Radio Monitoring

We present recent results of the TELAMON program, which is using the Effelsberg 100-m telescope to monitor the radio spectra of active galactic nuclei (AGN) under scrutiny in astroparticle physics, namely TeV blazars and neutrino-associated AGN since 2020. The radio variability of these sources and its correlation with high-energy activity are studied based on the first five years of monitoring within our long-term program. Additionally, we derive the polarization properties of candidate neutrino-associated and TeV-emitting blazar jets. Recent studies paint a picture of AGN being tied to ultrahigh-energy cosmic ray and neutrino emission, where the latter might be characteristically associated with radio flares in blazars. Studying the radio emission of these sources can provide crucial information on the high-energy emission processes, complementing multiwavelength studies in other wave bands. In this context the Effelsberg telescope yields superior radio data compared to other monitoring programs in the low flux-density regime due to its large dish aperture and sensitive instrumentation. This is particularly important as TeV-emitting blazars are typically faint radio sources. Our sample includes all known northern TeV-emitting blazars as well as blazars positionally coincident with IceCube neutrino alerts. We recover total intensity as well as polarization information at high radio frequencies up to 44GHz. Additional coordinated and triggered mm-VLBI observations of selected TELAMON sources help to get a more complete understanding of the physical processes in AGN jets that can lead to very-high-energy emission.

Speaker: Florian Eppel

16:35 Modeling of Blazar Multimessenger Emission with Convolutional Neural Network

Multimessenger observations, combining electromagnetic radiation and neutrinos, offer critical insights into the high-energy processes occurring in astrophysical sources. Recent coincident detections of high-energy neutrinos from the direction of blazars highlight them as ideal candidates for multimessenger modeling, and at the same time underscore the necessity of accurate modeling frameworks to interpret these complex signals. However, conventional hadronic models that explain neutrino emission from blazars are computationally intensive, complicating thorough parameter-space exploration and precise data fitting. In this presentation, I introduce a novel approach based on convolutional neural networks (CNNs), specifically designed to significantly accelerate the modeling of multimessenger blazar emissions. This CNN, trained on outputs from the SOPRANO numerical code, effectively and accurately reproduces the radiative signatures of protons, electrons, and secondary particles, transforming computationally demanding hadronic emission calculations into an efficient tool for rapid exploration and robust statistical fitting of observational data. I demonstrate the application and efficacy of this CNN-based method through fitting multimessenger observational data from blazars TXS 0506+056 and PKS 0735+178, showing the capability of the model to effectively constrain physical parameters and interpret multimessenger emission from blazar jets. This innovative methodology advances our understanding of blazar physics and provides a powerful analytical framework for future multimessenger astrophysics studies.

Speaker: Prof. Narek Sahakyan (ICRANET-Armenia IO)

15:20 → 16:50 NU: highlights & analysis

15:20 Hot-Coronae Stacking Analysis with the KM3NeT and ANTARES telescopes

The ANTARES telescope was a cherenkov neutrino telescope in the Mediterranean Sea which has taken data for 15 years. KM3NeT/ARCA is an astrophysical neutrino detector currently under construction, but already taking data. We present a binned likelihood stacking framework combining the two experimental datasets: the 15 years of ANTARES and the different KM3NeT/ARCA configurations (6, 8, 19 and 21 lines). We search for hot-coronae neutrino emission, both in a model-dependent and model-independent approach. For the former, we test the state-of-the-art hot corona models for 9 local Seyfert Galaxies. For the latter, we construct a catalogue of 30 Seyfert Galaxies using the B.A.S.S. AGN catalogue. We show our results testing both signal hypotheses comparing them with those recently published by the IceCube collaboration. The results of our analysis are useful for constraining the diffuse emission of these sources to the diffuse neutrino flux.

Speaker: Walid Idrissi Ibnsalih

15:35 Studying Neutrino Production Models in NGC 1068 with INTEGRAL

Recent works have proposed that high-energy neutrinos from active galactic nuclei can be explained by proton interactions close to the supermassive black hole, often in the corona. In the case of NGC 1068, model constraints from electromagnetic observations have come from Fermi/LAT observations in the GeV energy range. All of these models predict emission down to hard X-rays that is negligible compared to the expected inverse Compton emission from the corona. However, hard X-ray observations of NGC 1068 find unabsorbed fluxes ~10 times or more lower than the predicted corona fluxes. Thus we present a comparison of neutrino production models in NGC 1068 with INTEGRAL hard X-ray observations.

Speaker: James Rodi

15:50 Two 100 TeV Neutrinos Coincident with the Seyfert Galaxy NGC 7469

In recent years, neutrino astronomy has rapidly developed. In 2013, the IceCube collaboration announced the detection of an astrophysical neutrino flux. The origin of this flux is still largely unknown. The most promising source candidate is the close-by Seyfert galaxy NGC 1068, with evidence of 4.2 sigma and a soft spectral index.
In 2022 and 2023, two 100 TeV neutrinos, respectively IC220424A and IC230416A, were spatially coincident with the Seyfert galaxy NGC 7469 at a distance of 70 Mpc. Here, we report an a-posteriori evaluation for the chance coincidence of these two neutrinos with the source based on a Goodness-of-Fit test. We account for the neutrino angular uncertainties and the source distance and study how likely it is to have a similar doublet in coincidence with an X-ray emitting AGN or a Seyfert galaxy, both from dedicated catalogs.
Our test excludes an accidental spatial coincidence at a 3.2 sigma level, keeping open the possibility that the source emitted either one or both neutrinos. For compatibility with precedent IceCube non-detections, the neutrino emission of the source would need to follow a power law spectrum with hard spectral index or be peaked at high energies.

Speaker: Giacomo Sommani (Ruhr-Universität Bochum)

16:05 Investigating the neutrino emission of candidate neutrino-emitter blazars with the IceCubePy likelihood framework

Active galactic nuclei are promising candidates for astrophysical neutrino sources, as suggested by the detection of a high-energy neutrino positionally consistent with the flaring blazar TXS 0506+056 and evidence of neutrino emission from the nearby Seyfert galaxy NGC 1068. Our recent studies based on the IceCube time-integrated sky maps provided evidence of a statistically significant correlation between blazars and “hotspots” in the neutrino sky as seen by the IceCube Neutrino Observatory. A small subset of blazars, appearing as promising candidate neutrino point sources, has been highlighted. The neutrino emission properties of these blazars remain largely unexplored. The IceCube collaboration has publicly released a 10-year muon-track dataset, but no public analysis tools for analysing these data. In this contribution, we introduce “IceCubePy”, an unbinned maximum likelihood framework designed for the analysis of the public data from the IceCube Neutrino Observatory. We present the analysis performance of IceCubePy, showing that they are largely consistent with those published by the IceCube collaboration. We hence demonstrate that the software is mature and reliable for scientific analyses. Finally, we showcase its first scientific results, applying it to the candidate neutrino-emitter blazars.

Speaker: Dr Massimiliano Lincetto (University of Würzburg | DESY Zeuthen)

16:20 KM3NeT/ARCA stacking search for high-energy neutrinos from blazars

Blazars are promising targets for neutrino astronomy, as highlighted by IceCube’s identification of TXS 0506+056 as a cosmic neutrino source candidate. High-frequency-peaked BL Lacs (HBLs), a subclass of blazars, stand out due to their distinctive high-energy emission properties. Therefore, HBLs are promising candidates for the production of high-energy neutrinos. Such neutrinos could be detected by KM3NeT/ARCA, a next-generation deep-sea Cherenkov detector under construction in the Mediterranean Sea. Once completed, KM3NeT/ARCA will feature a cubic-kilometer detection volume capable of observing neutrinos across a wide energy range, from 100 GeV to multi-PeV. Its modular design ensures that partial operation and data acquisition are possible even during construction.

This contribution presents a binned likelihood stacking analysis framework to investigate high-energy neutrino emissions from HBLs using KM3NeT/ARCA data. The approach combines advanced statistical techniques with theoretical blazar models developed using the LeHa-Paris code. These models simulate the complex proton-photon interactions and radiative processes responsible for neutrino production, providing precise predictions of the resulting neutrino spectra. This particular analysis searches for cumulative (stacked) neutrino signals by comparing theoretical expectations with observational data for a subsample of HBLs from the 3HSP Catalogue. The aim of a stacking analysis is to increase the neutrino detection sensitivity, that may not be reached from individual sources alone.

Speaker: Francesco Carenini

16:35 Extreme blazars: stacking analysis with KM3NeT/ARCA

KM3NeT/ARCA is a large underwater Cherenkov neutrino detector, currently under construction at the bottom of the Mediterranean Sea. The detector geometry is optimised for the observation of TeV-PeV astrophysical neutrinos. Once completed, the detector will consist of 230 Detection Units (DUs). A Detection Unit is an 800-meter vertical line that holds 18 Digital Optical Modules, containing 31 photomultiplier tubes each.
This contribution presents a study of Extreme High-energy Synchrotron Peaked (EHSP) blazars. The energy of the EHSP synchrotron peak is the highest among blazars and these “extreme blazars” are particularly relevant for high-energy astrophysics since they may emit high-energy neutrinos in the energy range where Cherenkov detectors such as KM3NeT/ARCA are sensitive.
This study is a likelihood stacking analysis using KM3NeT/ARCA data collected in a partial detector configuration with 21 active DUs. The neutrino fluxes of selected extreme blazars are computed using LeHaMoC numerical modeling code and then compared with KM3NeT/ARCA observations.

Speaker: Maria Rosaria Musone (INFN napoli)

15:20 → 16:50 NU: instruments and applications

15:20 EUSO-SPB2 Cherenkov Telescope: Overview and First Neutrino Constraints

Earth-skimming tau neutrinos with energies above $\sim 10$ PeV can convert to tau leptons that decay in the atmosphere and initiate upward-going extensive air showers that generate optical Cherenkov signals. On a curtailed NASA balloon flight in May 2023, the Cherenkov telescope (CT) on the Extreme Universe Space Observatory on a Super Pressure Balloon 2 (EUSO-SPB2) was launched and had a short flight at $\sim 30$ km altitude. With some time pointing below the Earth’s limb, EUSO-SPB2 CT data allow searches for neutrino events that yield optical flashes from the forward-beamed Cherenkov light. We present an overview of the CT and report on sensitivity limits for the diffuse astrophysical neutrino flux from flight data as a proof-of-principle demonstration. We also briefly describe how the methodology is extended to potential transient neutrino point sources.

Speaker: Mary Hall Reno

15:35 Probing the Earth’s Mantle Transition Zone and Large Low-Velocity Provinces with Neutrino Oscillation Tomography

Neutrino oscillation tomography has the potential to complement classical geophysical and geochemical methods for probing the Earth's deep interior. This technique relies on identifying changes in neutrino oscillation patterns due to variations in the matter density and the proton-to-nucleon ratio distribution in the materials through which neutrinos pass. Consequently, open questions regarding the density distribution and chemical composition of the Earth's interior can be addressed with this novel method.

In this contribution, we present the sensitivity of neutrino oscillation tomography to the aforementioned properties of each Earth layer, considering a spherically symmetric Earth model. Our goal is to identify which depth ranges can be most effectively studied using this technique. To understand the constraints that neutrino oscillation tomography can provide on Earth structure, we first derive the sensitivity to the planet's composition and density, assuming an ideal neutrino detector. Next, we incorporate the response of next-generation neutrino telescopes. We show that while an ideal detector is most sensitive to the outer core, realistic detectors with lower resolution but large detection volumes are more sensitive to shallower depths.

Finally, making use of the recent implementation of a 3-dimensional Earth Model in the OscProb programming library, which handles the calculation of oscillation probabilities for a given neutrino trajectory, we investigate the possibility of characterizing heterogeneous structures. Here, we focus on the sensitivity to asymmetrical water distribution in the mantle transition zone (MTZ). Initial evidence suggests that the MTZ beneath Asia may contain significantly more water than that beneath Europe. To explore this, we assess the feasibility of combining measurements from neutrino detectors across these two continents to constrain the water content in these regions.

Speaker: Isabel Goos

15:50 State of the Ice Model in IceCube observatory

IceCube is a neutrino observatory located at the South Pole that uses Antarctic ice as a medium for detection of Cherenkov photons. As such, analysis of the data relies on our understanding of the properties of ice within and around the instrumented volume. Over the years we have made significant progress in understanding the glacial ice and now have a comprehensive model that covers many of the relevant aspects of the photon propagation in it. In this report we give a historical overview of the ice description within the IceCube detector, list some of the remaining issues, and assess how much more improvement is still needed. As the IceCube Upgrade is expected to be installed in less than a year, with several new types of calibration devices aiming to further our understanding of ice, this is the perfect time to review the current state of the ice model.

Speaker: Dmitry CHIRKIN

16:05 Updated Earth Tomography Using Atmospheric Neutrinos at IceCube

The IceCube Neutrino Observatory has observed a sample of high purity, primarily atmospheric, muon neutrino events over 11 years from all directions below the horizon, spanning the energy range 500 GeV to 100 TeV. While this sample was initially used for an eV-scale sterile neutrino search, its purity and spanned parameter space can also be used to perform an earth tomography. This flux of neutrinos traverses the earth and is attenuated in varying amounts depending on the energy and traversed column density of the event. By parameterizing the earth as multiple constant-density shells, IceCube can measure the upgoing neutrino flux as a function of the declination, yielding an inference of the density of each shell. In this talk, the latest sensitivities of this analysis and comparisons with the previous measurement are presented. In addition, the analysis procedure, details about the data sample, and systematic effects are also explained. This analysis is the latest, weak-force driven, non-gravitational measurement of the earth’s density and mass.

Speaker: Alex Wen

16:20 Development of monitoring and control strategies for biofouling and sedimentation for the Pacific-Ocean Neutrino Experiment

The Pacific-Ocean Neutrino Experiment (P-ONE) is a new neutrino telescope that is currently under construction in the North Pacific Ocean. The future location of the detector is the Cascadia Basin, a flat 2660 m deep region of ocean off the coast of Vancouver Island, Canada. P-ONE will be made up of one kilometre long strings of optical instrumentation. The collaboration is currently working towards the assembly and deployment of the first string. A pathfinder instrument took data at the P-ONE site from August 2018 until July 2023. Data from the pathfinder shows that upwards facing instruments lost some transparency over its 5 year lifetime. This is attributed to the deposition of marine sediments and subsequent colonization by biological organisms, collectively referred to as biofouling. Pathfinder results concerning biofouling will be discussed in this contribution. In addition, we will discuss the usage of surface modifying coatings for biofouling mitigation on future P-ONE instruments. The inclusion of this technology is novel for neutrino telescopes and a candidate coating will be tested in-situ on the first string.

Speaker: Braeden Veenstra (University of Alberta)

16:35 Neutrino search by TA SD

In this talk, we present a search strategy for neutrino-induced air showers using the Telescope Array surface detectors (TA SD), focusing on the large zenith angle region. To develop the analysis method, we used Monte Carlo (MC) simulations. In previous TA analyses, the MC generation method was established only for proton showers with zenith angles up to 60 degrees. Therefore, we validated and implemented a new MC generation method specifically for large-zenith-angle neutrino showers. Additionally, we investigated the reconstruction method and developed an optimized approach for large-zenith-angle neutrinos. Using the generated MC, we explored a method to distinguish neutrino showers from proton showers. In this talk, we introduce this new neutrino search method for the TA experiment. The established methodology will be applied to real data collected by the TA SD to conduct a neutrino search.

Speaker: Kaoru Takahashi

16:50 → 17:05 Break

17:05 → 18:20 CRD: transport

17:05 Numerical Investigation of Cosmic Ray Spectral Features

High-precision cosmic ray measurements from both space-based and balloon-borne experiments have revealed a variety of spectral features. Primary nuclei and their secondaries produced during propagation exhibit spectral hardening above $\sim$200 GV. Proton-spectrum softening has been observed at $\sim$10 TeV. Helium-spectrum softening has been observed at slightly higher energies. A positron excess above $\sim$25 GeV has also been observed. The cosmic-ray propagation code GALPROP v57 was utilized to study these features. GALPROP v57’s parameter optimization module, utilizing the minimization library MINUIT2, was applied to find the best fit to the experimental data. As a baseline, the plain diffusion model with reacceleration and convection effects is employed. To study the hardening, three cases were explored: (1) a break in the diffusion coefficient, (2) breaks in the injection spectra, and (3) a combination of both. To account for the proton and helium spectra softening, an additional source break was introduced. A charge-symmetric primary positron source was introduced for the positron excess. We will compare the results for the elemental spectra and ratios, as well as the all-particle spectrum, to compiled cosmic-ray data. Additionally, we will discuss the implications of these findings.

Speaker: Yuca Chen (University of Delaware)

17:20 Cosmic Ray Transport and Gamma-Ray Signatures in the Interstellar Medium

Cosmic rays (CRs) interact with turbulent magnetic fields in the interstellar medium (ISM), generating non-thermal emission. Recent ultra-high-energy gamma-ray (UHEGR) observations by LHAASO, linked to star-forming regions in the ISM, have introduced new challenges in understanding CR acceleration and propagation in these environments. Despite decades of study, the diffusion of CRs within the sources and the ISM remains a major theoretical challenge. We combined 3D magnetohydrodynamic (MHD) simulations of star-forming regions with test particle simulations to investigate CR diffusion, focusing on the role of mirror diffusion and its interplay with standard resonant scattering diffusion. Our results indicate that mirror diffusion plays a crucial role in regulating CR transport parallel to the magnetic field, leading to significantly slower overall diffusion. Our simulations indicate a diffusion coefficient of ∼10^{27}cm^2/s for particles with energies of a few hundred TeV within a few parsecs of their source - 10 to 100 times smaller than standard predictions. This finding aligns with the UHEGR observations, which require suppressed CR diffusion in localized regions. Additionally, we present results from 3D Monte Carlo simulations of CR cascading within a massive stellar cluster environment, derived from a 3D MHD simulation, where CR diffusion incorporates both mirroring and scattering. These systems are prime candidates for explaining the origin of observed UHEGRs in the Galaxy, and we will present the resulting integrated gamma-ray flux from our simulations.

Speaker: Lucas Barreto Mota dos Santos (Universidade de São Paulo - IAG)

17:35 Updated Limits on Anisotropy in Electron+Positron Cosmic Rays from CALET Data

The ISS-based Calorimetric Electron Telescope (CALET) is directly measuring the energy spectrum and direction distribution of electron+positron cosmic-rays up to 20 TeV. The electron+positron events measured by CALET have been analyzed for a possible dipole anisotropy, which could be a signature of nearby SNR such as Vela.
The methods used to derive limits on the anisotropy from the reconstructed events are explained, including the procedures to compensate for non-uniform sky exposure and inhomogeneous detector acceptance. Upper limits on the dipole moment as a function of lower threshold energy, with doubled statistics compared to previously shown results, are presented.

Speaker: Holger Motz (Waseda University)

17:50 Measurements of separate electron and positron spectra from 10 GeV to 20 GeV with DAMPE mission

The cosmic-ray(CR) electrons and positrons are of great significance for studying the origin and propagation of cosmic-rays. The satellite-borne experiment DArk Matter Particle Explorer(DAMPE) has been used to measure the separate electron and positron spectra, as well as the positron fraction. In this work, the Earth's magnetic field is used to distinguish CR electrons and positrons, as the DAMPE detector does not carry an onboard magnet. Considering the pointing and acceptance of DAMPE on orbit, the energy range for the measurements introduced in this work is 10 to 20 GeV. The results are consistent with the previous measurements based on magnetic spectrometer, like AMS-02.

Speaker: Yu Nie (University of Science and Technology of China)

18:05 Estimation of temporal and spatial distributions of high-energy cosmic-ray electron sources using genetic algorithms

Over the last decade, highly accurate high-energy cosmic-ray electron energy spectra have been obtained with superior instruments such as CALET. Their energy spectra, which show characteristic structures, have the potential to unveil the origin of cosmic-ray electrons whose most likely candidates are supernova remnants (SNRs). In this work, we estimate the intragalactic temporal and spatial distributions of SNRs from the observed electron spectra. We apply genetic algorithms to represent the observed electron spectra with the calculated flux of high-energy electrons from SNRs distributed in the Galaxy. This work will allow us to verify the SNR origin hypothesis of cosmic rays and to predict the ages/distances of unknown SNRs.

Speaker: Prof. Kenji Yoshida (Shibaura Institute of Technology)

17:05 → 18:35 CRI: phenomenology

17:05 Combined fit above 0.1 EeV to the cosmic-ray spectrum and composition measured with the Pierre Auger Observatory

We fit the cosmic-ray spectrum measured with the Pierre Auger Observatory's surface detectors above an energy of $10^{17}$ eV, along with composition information inferred from the depth of shower maximum measured with its fluorescence detectors above an energy threshold of $10^{17.8}$ eV. We consider astrophysical scenarios with two distinct extragalactic source populations: one dominating the flux above a few EeV, and the other dominating at lower energies, with representative nuclei injected at the sources with power-law spectra and rigidity-dependent cutoffs. The high-energy population exhibits a hard source injection spectrum and a relatively heavy composition, while the low-energy population has a softer spectrum and a lighter composition. Extending the fit down to the low energies considered here shows the potential to test the energy region towards the Galactic to extragalactic transition with the data of the Pierre Auger Observatory.

Speaker: Esteban Roulet

17:20 Probing the Cosmic-Ray Proton Fraction with Cosmogenic Multi-PeV Neutrinos and Gamma-rays Constraints

The recent detection of a multi-PeV neutrino event by KM3NeT/ARCA opens a new window into the origins of ultra-high-energy cosmic rays (UHECRs). We revise the possibility of a cosmogenic origin for this event while considering constraints from the diffuse extragalactic gamma-ray background (EGRB) observed by Fermi-LAT and the non-detection of ultra-high-energy (UHE) photons ($\gtrsim$ EeV) by Auger.
We find that cosmogenic cascade photons may impose even stronger constraints on the allowed proton fraction of UHECRs than neutrinos, depending on the redshift evolution of cosmic accelerators. Additionally, we examine limits on the proton fraction at energies E $\gtrsim$ 10$^{19}$ eV, informed by the inferred cosmogenic neutrino flux from the new KM3NeT detection and the absence of neutrinos above a few PeV in Auger and IceCube data. These results take on particular importance in light of upcoming observations by AugerPrime, which will directly probe UHECR composition and provide key insights into the luminosity and evolution of cosmic-ray sources across cosmic time.

Speaker: Alessandro Cermenati (Gran Sasso Science Institute)

17:35 Implications of temporal features of UHECR fluxes on large scale anisotropies

The origin of ultra-high-energy cosmic rays (UHECRs) is still an elusive question, mainly because the arrival directions do not point to a preferred source location. However, it has recently been observed that the amplitude of the dipole anisotropy detected by the Pierre Auger Observatory increases with the energy. This can be interpreted as an indication of the presence of a dominant source in the direction of the dipole, depending on the effects of the Galactic Magnetic Field (GMF). However, alternative interpretations need to be rigorously examined and ruled out before any final conclusions on the dipole anisotropy can be accepted. Using CRPropa 3.2 and current GMF models, we find that UHECRs entering the Milky Way can experience delays of hundreds of kiloyears in the range of rigidities observed by Auger. Based on the constructed spectrum of ages for observed UHECRs , we explore the possibility that temporal changes in the flux of UHECRs can produce a dipole similar to that reported by Auger. We identify scenarios consistent with our hypothesis and discuss the implications for our interpretation of the observations.

Speaker: Karl-Heinz Kampert (Universität Wuppertal)

17:50 Investigating Non-Accreting Supermassive Black Holes as Sources of Ultra-High-Energy Cosmic Rays

Over the past decade, giant surface arrays such as the Pierre Auger Observatory and the Telescope Array have detected cosmic rays with energies reaching hundreds of EeV, yet their sources remain unidentified. The detection of a large-scale dipole anisotropy pointing away from the Galactic plane, combined with the attenuation of ultra-high-energy cosmic rays (UHECRs) during propagation, suggests that their origins lie in nearby extragalactic objects. Most source searches have focused on starburst galaxies and radio-loud active galactic nuclei, which are galaxies hosting a supermassive black hole (SMBH) at their core. As a result, Centaurus A has been identified as a promising candidate. Theoretical models suggest that spinning SMBHs threaded by magnetic fields can accelerate charged particles to ultra-high energies. However, it remains unclear how primary cosmic rays, especially heavier ones, can survive and escape their acceleration region. In this work we start by considering that large-scale magnetic fields can arise also in the absence of intense AGN activity, suggesting that non-accreting SMBHs may also contribute to the UHECR flux favoring the survival of the heavy component observed at the end of the primary energy spectrum. Using the latest published data from the Pierre Auger Observatory, we perform a correlation analysis between UHECRs above 20 EeV and a catalog of SMBHs with precisely measured masses. We present results for the full catalog and separately assess the contributions from active and non-active populations. Additionally, we conduct a likelihood ratio test to compare the active and non-active hypotheses.

Speaker: Elena Manao

18:05 Active Galactic Nuclei Jets Enriched by Wolf-Rayet Stars and Their Possible Contribution to Ultra-High-Energy Cosmic Rays

Despite all that we have learned from observational data, the sources of ultra-high-energy cosmic rays (UHECRs) have not yet been identified. Among the candidates discussed in the literature, starburst galaxies and active galactic nuclei (AGNs) are likely the most popular. Studies from the Pierre Auger Observatory indicate that the mass composition of particles with energies above $10^{19.3}$ eV is compatible with Carbon-Nitrogen-Oxygen (CNO) nuclei. While starburst galaxies contain the necessary CNO elements, their energy budget has been shown to be insufficient to accelerate UHECRs beyond 1 EeV. In contrast, radiogalaxies, a subclass of AGNs, provide the required energy through their powerful jets. The lepton-dominated nature of these jets, however, makes the presence of nuclei nontrivial, requiring a mass-loading mechanism. One possible process for introducing nuclei into these jets is the interaction with embedded stars. In this work, we investigate the role of Wolf-Rayet (WRs) stars, which have CNO-rich winds, in supplying intermediate-mass nuclei to AGN jets. By exploring typical parameters for radiogalaxies, we estimate the resulting integrated UHECR flux and find solutions consistent with the flux detected by the Pierre Auger Observatory, suggesting that WR stars can supply sufficient CNO and heavier nuclei to be accelerated in AGN jets. We also discuss our results for the expected mass-composition fractions and the spectrum observed on Earth after propagation, particularly for a Centaurus A-like galaxy at different distances.

Speaker: Dr Ana Laura Müller (FZU - Institute of Physics of the Czech Academy of Sciences)

18:20 Constraining UHECR source parameters assuming a cosmogenic origin of KM3-230213A

Various models were proposed to explain the observed spectrum and composition of ultra-high-energy cosmic rays (UHECRs), but they remain inconclusive in constraining their source of origin. A significant neutrino event with an estimated energy between 72 PeV and 2.6 EeV was recently observed by the KM3NeT experiment (henceforth referred to as KM3-230213A). When interpreted as cosmogenic in origin, this event can provide constraints on the models of UHECRs.
In this contribution, we aim to constrain a two-population model of UHECRs using the cosmic-ray data of the Pierre Auger Observatory and KM3-230213A. The first population is mixed in composition, while the second population is comprised of ultra-high-energy (UHE) protons with a higher maximum rigidity. We present the parameter ranges around the best-fit solution to the spectrum and composition of UHECRs that is consistent with the detection of a single neutrino event by the KM3NeT detector at the energy range of KM3-230213A. This leads to constraints on the fraction of protons in UHECRs and the source evolution with redshift. Preliminary results indicate that a population of UHE protons with a strong source evolution (similar to the evolution of high-luminosity active galactic nuclei) is favored.

Speaker: Abdulrahman Alhebsi (Khalifa University of Science and Technology)

17:05 → 18:35 GA: GRBs, FRBs, transients

17:05 First Simultaneous TeV Observations of Non-Repeating Fast Radio Bursts with VERITAS

The origin of Fast Radio Bursts (FRBs) remains a longstanding and intriguing mystery. Discovering their progenitors will increase our knowledge of compact objects in extreme environments and will improve the use of these sources to probe cosmology and the structure of galaxies. A key discriminator between various models is the presence of multiwavelength counterparts. Although previous non-detections of TeV emission around several distant repeating FRBs have been reported, non-repeating FRBs appear to be emerging as a distinct source class where models predicting simultaneous high-energy emission remain viable. Investigating non-repeating sources is extremely challenging, as the transient nature of these events often precludes timely multiwavelength follow-up observations. Here, we present the first simultaneous TeV observation of a non-repeating FRB with VERITAS and place deep constraints on gamma-ray burst (GRB) models using a coincident FRB. We discuss the implications of these observations on FRB models and the challenges in improving these results with next-generation imaging atmospheric Cherenkov telescopes.

Speaker: Matthew Lundy (McGill University)

17:20 Investigating Fast Radio Bursts with H.E.S.S.: Multi-Wavelength Follow-Up and Constraints on Gamma-Ray Emission

Fast Radio Bursts (FRBs) are brief, highly energetic radio flashes of unknown origin. Their high luminosity, short duration, and large dispersion measures suggest an extragalactic origin, potentially linked to extreme astrophysical objects such as magnetars. The growing number of detected FRBs, including repeating sources, has driven extensive multi-wavelength follow-up efforts. While FRB 20200428A has been associated with the Galactic magnetar SGR 1935+2154, no other FRB has yet been conclusively linked to a multi-wavelength counterpart.
In this contribution, we present the follow-up program developed by the High Energy Stereoscopic System (H.E.S.S.) to search for gamma-ray counterparts to FRBs. We provide an overview of FRB observations conducted by H.E.S.S. from 2015 to 2022, including targeted follow-ups and coordinated multi-wavelength campaigns with radio and X-ray observatories. Among the observed FRBs, 10 have well-determined redshifts ranging from 0.11 to 0.49. No significant very high energy (VHE) emission was detected, allowing us to place constraints on VHE luminosity across different timescales.

Speaker: Federica BRADASCIO (IJCLab - Université Paris-Saclay)

17:35 Revisiting Two Decades of GRB Observations: Assessing Missed Very High-Energy Detections and Future Prospects

Gamma-ray bursts (GRBs) are bright flashes of electromagnetic radiation originating from the core collapse of massive stars or the merger of compact objects. It has long been theorized that GRBs can emit very high-energy (VHE) gamma rays that can reach the TeV level. Although current-generation Imaging Atmospheric Cherenkov Telescopes (IACTs), such as H.E.S.S., have been observing GRBs since 2002, the first detection of GRBs by IACTs occurred only 16 years later, in 2018, raising the question of why no detections were made during these years. We investigate all GRBs detected by the Swift Observatory with redshift measurements over the past two decades. Using the phenomenological relationship between X-ray and gamma rays and taking into consideration EBL absorption effects and instrument response functions, we search for any missed opportunities for GRBs that could have been detected by the three IACTs: H.E.S.S., MAGIC, and VERITAS, and present the best candidates. We find that the missing detections can be explained by the low rate of detectable GRBs at VHE, which we quantify as < 1 per year. We also find that with the future Cherenkov Telescope Array Observatory (CTAO), this rate can increase to 4 per year.

Speaker: Halim Ashkar (Laboratoire Leprince-Ringuet, E ́cole Polytechnique, CNRS, Institut Polytechnique de Paris, F-91128 Palaiseau, France)

17:50 The Biggest Bangs: Traces of turbulence in GRBs.

Gamma-ray bursts (GRBs) are the most powerful transient explosions in the Universe and emit a vast amount of their energy in the form of gamma-rays. Although they last extremely short on cosmic time scales, their gamma-ray emission shows a wealth of temporal variability. Properties of this variability may carry information about the processes the gamma-rays emerge from, which remain poorly understood. This research investigates the redshift-corrected gamma-ray light curves of GRBs with known redshift, and the observer-frame gamma-ray light curves of GRBs without redshift, all observed by the Gamma-Ray Burst Monitor on the Fermi Gamma-Ray Space Telescope between 2008 and 2023.

We calculate the average power-density spectrum (PDS) of different GRB groups, categorized by fluence, peak rate, duration, redshift, and, for the first time, distinguish between the different GRB phases. We compare the resulting PDS profiles with their corresponding noise profiles, a comparison that has not been done previously. Our results reveal clear differences in the spectra of long and short bursts, precursor and prompt phases, and signal versus noise regions.

Previous studies have reported slopes consistent with a value of -5/3 Hz, associated with fully developed turbulence (Kolmogorov turbulence), suggesting that the gamma-rays in GRBs are produced by turbulent processes. Our analysis shows that almost all redshift-corrected spectra exhibit a power-law behavior with indices around -1.9 Hz. Notably, the precursor phase and redshift-corrected short bursts display a shallower power-law with indices of approximately -1.5 Hz. This indicates the presence of a different type of turbulence in some GRBs and phases.

Speaker: Else Magnus (Vrije Universiteit Brussel (VUB-IIHE))

18:05 LST-1 observations of GRB 221009A: Insights into its late-time VHE afterglow

Gamma-ray bursts (GRBs) originate from explosions at cosmological distances, generating collimated jets. GRB 221009A, triggered on 9 October 2022, has been established as the brightest GRB to date. Its bright and long emission was extensively followed up from radio to gamma rays. LHAASO firmly detected the onset of the afterglow emission at energies up to ~13 TeV within about an hour after the burst, starting just a few minutes after the trigger. While this VHE emission component can be accounted for in a narrow jet scenario, such an interpretation cannot reproduce the broadband emission observed at later times, which exceeds the theoretical expectations. This discrepancy can be settled if more complex models are considered, providing the first strong evidence for a structured jet in a long GRB. Unfortunately, the VHE emission after a few hours is poorly constrained, as sensitive VHE observations by Cherenkov Telescopes were prevented due to strong moonlight conditions. The first Large-Sized Telescope (LST-1) of the future Cherenkov Telescope Array Observatory began observations about one day after the burst under high night sky background conditions. These observations are the first ones performed on GRB 221009A by a Cherenkov telescope, revealing a hint of a signal with a statistical significance of about 4$\sigma$ during the observations performed at 1.3 days after the burst. The monitoring campaign continued until the end of November 2022, making it the deepest observation campaign performed on a GRB with the LST-1. In this contribution, we will present the analysis results of the LST-1 observation campaign on GRB 221009A in October 2022, compare them with theoretical models, and discuss their physical implications.

Speaker: Arnau Aguasca-Cabot (Universitat de Barcelona - ICCUB - IEEC)

18:20 Transient Observations with LST-1: Key Results and Future Prospects

The recent detections of the afterglow phase of long gamma-ray bursts (lGRBs) at very high energies (VHE, >100 GeV) mark a significant advance in astrophysics of transient phenomena, offering deeper insights into the acceleration mechanisms, jet structure, and physical processes driving GRB emission. In the multi-messenger landscape, both high-energy neutrino and gravitational-wave detections are providing new insights into the physics of extreme cosmic accelerators, and highlight the need for rapid and broadband follow-up observations.

The Large-Sized Telescope (LST-1), the first prototype telescope for the Cherenkov Telescope Array Observatory (CTAO), is particularly well suited for real-time rapid follow-up of transients with its fast slewing capabilities, large effective area, and exceptional sensitivity below 100 GeV. In this contribution, we present the latest achievements of the transient observational program with LST-1, which is now in advanced commissioning on La Palma, Canary Islands. We outline the observational strategies in place and describe the dynamic handling of events by the transient handler of LST-1 (e.g., its ability to handle poorly localised events including gravitational waves, GRBs and neutrinos). We present the key results from transient observation campaigns conducted so far, discuss the lessons learned, and outline the promising prospects for the future LST-1+MAGIC combined transient program with fast response, via a unique Transient Handler.

Speaker: Monica Seglar-Arroyo (Institut de Fisica d'Altes Energies (IFAE))

17:05 → 18:21 GA: galactic diffuse emission

17:05 Spectral shape of galactic cosmic rays: Modeling and implications on diffusive gamma-ray emission

Recently, LHAASO has announced the highest-energy measurements of the diffusive gamma-ray flux, offering the possibility of probing the spatial distribution and energy spectrum of the galactic cosmic rays (CRs) up to the all-particle spectrum knee ($\sim 4$ PeV). However, a persistent tension between observations by experiments (such as Fermi and LHAASO) and the predictions based on measurements of the local CR flux increase the necessity of a robust model of the CR spectrum. In the present work, we estimate the gamma-ray flux coming from CRs with energies as high as the knee. We developed a phenomenological model of the galactic CR flux using the latest data available by satellite missions and ground-based observatories. In particular, our model identifies the series of spectral breaks found in the proton and helium fluxes in the range of $10^2$ to $10^7$ GeV and corroborates that these breaks are located at the same rigidity for different CR species. In contrast with other models, our analysis also includes the most recent measurements of the proton spectrum by the GRAPES-3 experiment, showing an additional spectral break at $\sim 160$ TeV. We also include the uncertainty related to the contribution of heavier nuclei in the CR composition. We compare our expected gamma-ray flux with previous models and recent observational data, focusing our discussion on the new spectral features provided by our model.

Speaker: Luis Enrique Espinosa Castro (Gran Sasso Science Institute)

17:20 Diffuse emission from stochastic sources

Diffuse emission in gamma-rays and neutrinos are produced by the interaction of cosmic rays with the interstellar medium. Below some hundreds of TeV, the sources of these cosmic rays are most likely Galactic. Hence, observations of high-energy gamma-rays and neutrinos can be used to probe the flux of cosmic rays in other parts of the Galaxy. Supernova remnants are usually considered as the prime candidate for the acceleration of Galactic cosmic rays. They inject cosmic rays in a point-like and specific time-dependent manner. As the precise positions and ages of the sources are not known, predictions must be obtained in a stochastic model. At GeV energies, the distribution of sources can be approximated with a smoothly varying spatial and temporal source density. At hundreds of TeV, however, the point-like nature matters as less sources contribute effectively due to shorter escape times. We have modelled diffuse emissions at hundreds of TeV, relevant for measurements by LHAASO, Tibet AS-gamma, IceCube, and the upcoming SWGO, as well as at tens of GeV, as measured by Fermi-LAT. This reveals the distinctive nature of diffuse emissions at the respective energies which can likely be used to constrain source models and locate cosmic ray sources.

Speaker: Anton Stall (Institute for Theoretical Particle Physics and Cosmology (TTK), RWTH Aachen University)

17:35 Testing the influence of anisotropic CR transport and the Galactic magnetic field structure on the all sky gamma-ray emission

The spatial diffusion of energetic particles in a magnetic field composed of a large-scale background and a small-scale turbulent component should be expected to be anisotropic. While such anisotropic diffusion has been known for quite a while in first-principle plasma physics and while it is required for an understanding of the transport of cosmic rays in the heliosphere or close to supernova remnants, only in recent years it has also become of particular interest for the modeling of Galactic cosmic ray (GCRs) transport in the Milky Way in the context of their residence time and their (local) energy spectra. The large-scale spatial distribution of GCRs is shaped by an anisotropic diffusion in the Galactic magnetic field which should directly affect both the diffuse gamma-ray and the neutrino emission.

In this talk, I will demonstrate that an anisotropic diffusive transport of GCRs in the Milky Way has an imprint on the all-sky gamma-ray emission in the GeV to TeV range. For this we calculate the CR distribution in the Milky Way considering anisotropic transport using the public CRPropa framework and estimate the line-of-sight emission with the HERMES package. Finally, I will discuss the feasibility of gamma-ray observations to constrain not only the parameters of such anisotropic transport but also the structure of the Galactic magnetic field.

Speaker: Julien Dörner (Ruhr University Bochum)

17:50 An Interpretation of Sub-PeV Galactic Diffuse Gamma-Ray Observations by the Tibet ASγ Experiment and LHAASO

Galactic diffuse gamma-rays emission (GDE) in the sub-PeV energy range (E > 100 TeV = $10^{14}$ eV) was first detected by the Tibet AS$\gamma$ experiment in 2021, ensuring the presence of PeV cosmic-ray accelerators in the Galaxy. On the other hand, in 2023 the Large High Altitude Air Shower Observatory (LHAASO) detected GDE covering an energy range between 10 TeV and 1 PeV. Interestingly, the sub-PeV GDE flux measured by LHAASO from the inner Galactic Plane region ($15^{\circ} < l < 125^{\circ}$ and $|b| < 5^{\circ}$) is lower than that measured by Tibet AS$\gamma$ ($25^{\circ} < l < 100^{\circ}$ and $|b| < 5^{\circ}$) by a factor of five. To study the discrepancy between the results of the two observatories, we estimate the contamination of the Tibet GDE flux from the sub-PeV gamma-ray sources presented in the first LHAASO catalog, accounting for the source masking scheme used in the Tibet GDE analysis. We find that the source contamination of the Tibet GDE flux is less than 30% in the sub-PeV energy range and cannot explain the discrepancy between the Tibet and LHAASO GDE fluxes. Using a GDE theoretical model of Lipari and Vernetto (2018), we also find that the residual discrepancy can be accommodated with the GDE flux from the source masking regions in the LHAASO GDE analysis. Our result supports that the Tibet GDE flux is indeed dominated by GDE and shows some important implications such as a fraction of GDE over the total Galactic sub-PeV gamma-ray emission and significant GDE contamination of the Cygnus Super Bubble.

Speaker: Sei Kato (Institut d'astrophysique de Paris)

18:05 Modelling Galactic CRs and the Diffuse Gamma-Ray Emission

Galactic diffuse gamma-ray emissions have been observed from MeV to PeV energies.
These emissions are connected via a common origin of the cosmic ray (CR) particles, but the energy dependence and hadronic/leptonic fraction remain unconstrained.
We model the Galactic CR distributions and associated non-thermal diffuse emissions from TeV--PeV energies using the GALPROP framework.
We investigate the modelling uncertainty over a grid of steady-state 3D models that include variations over the ISM target distributions and the CR source locations.
We also estimate the time-dependent modelling uncertainties when considering ensembles of CR sources with discrete and finite lifetime, e.g. supernova remnants, for a range of creation rates and active times.

Our predictions are compared to diffuse emission estimates from the high-energy stereoscopic system (H.E.S.S.) and LHAASO observations after accounting for resolved and unresolved source fluxes.
We show that these >TeV observations can be described by our models tuned at GeV energies without any alterations to the underlying physics and assumptions.

Over the range of distributions we consider, variations in the diffuse VHE emissions can be ~25% for both the steady-state and time-dependent models.
The variations due to the differing descriptions of the ISM are an important factor that must be reduced through other multi-messenger constraints on the MW.
The variations due to the discrete/finite nature of the CR sources are critical to consider when describing physical models of the diffuse emissions from the Galaxy at VHE/UHEs.

Speaker: Peter Marinos (Stanford)

17:05 → 18:35 GWMS: numerical analysis

17:05 MCMC Parameter Study of the Multimessenger Emission from AGN-Starburst Galaxies

Active Galactic Nuclei (AGN) and starburst galaxies are multimes-
senger sources in the Universe, emitting from radio/infrared energies
to gamma-ray and neutrino energies. NGC 1068 is a Seyfert II galaxy
with a starburst ring that has been proven to emit the neutrinos de-
tected by Icecube through hadronic processes most likely happening
in the AGN corona. Two high-energy neutrinos with high probability
of being of astrophysical origin have recently been reported by Ice-
Cube from the direction of NGC7469 as well. In this presentation, we
model the different environments of these AGN-starburst composite
sources and constrain the main parameters for the AGN and starburst
environments using a Markov Chain Monte Carlo approach (MCMC),
where we include the data from radio to TeV energies

Speaker: Silvia Salvatore

17:20 CCSNe detection perspectives with 3G GW detectors

The collapse of the core of a massive star at the end of its life can give rise to one of the most powerful phenomena in the Universe. Because of violent mass motions that take place during the explosion, Core Collapse Supernovae have been considered a potential source of detectable gravitational waveforms for decades. However, their intrinsic stochasticity makes almost impossible modeling and predicting the outcome of these processes, forcing us to develop model independent technique to unveil their nature. In this work, a deep learning approach, based on on a classification procedure of the time-frequency images using a Convolutional Neural Network, has been explored and its performances has been tested on the future 3G Gravitational Wave detectors.

Speaker: Alessandro Veutro (Sapienza Università di Roma)

17:35 New Public Neutrino Alerts for Clusters of IceCube Events

The IceCube Neutrino Observatory searches for the origins of astrophysical neutrinos using various techniques to overcome the significant backgrounds produced by cosmic-ray air showers. One such technique involves combining the neutrino data with other cosmic messengers to identify spatial and temporal correlations. IceCube contributes to multi-messenger astrophysics by providing alerts for interesting events observed in the detector. The Gamma-ray Follow-Up (GFU) cluster alert system is one stream that identifies potential neutrino flares in realtime, producing around 20 alerts per year. GFU cluster alerts have been privately shared with Imaging Air Cherenkov Telescopes (IACTs) through memorandums of understanding since IceCube’s predecessor, AMANDA. To preserve blindness to the full behavior of our data, the current system mutes updates from sources following the initial GFU alert sent, preventing further updates until the activity drops below the alert threshold. With growing knowledge of the potential environments that produce astrophysical neutrinos and to foster open collaboration, the GFU alerts will shift to be publicly shared. Additionally, the new alert platform will provide all above threshold information such that the source behavior after the initial alert is not obscured. The above threshold data will be distributed through an interactive website that will update the community on the status of active GFU alerts. This presentation will introduce the new GFU platform and the accompanying website, soon to be accessible to the MMA community.

Speaker: Sarah Louise Mancina (INFN-Padova)

17:50 Archival Search for IceCube Sub-TeV Neutrino Counterparts to Sub-Threshold Gravitational Wave Events from the Third Observing Run of the LIGO-Virgo-KAGRA

The IceCube Neutrino Observatory actively participates in multi-messenger follow-ups of gravitational-wave (GW) events. With the release of the Gravitational-Wave Transient Catalog (GWTC)-2.1 and -3, the sub-threshold GW event information from the third observation run of the LIGO-Virgo-KAGRA (LVK) detectors is publicly available. These sub-threshold GWs are identified via template-based and minimally-modelled search pipelines. Neutrino counterparts can enhance their astrophysical significance, and improve their localisation. In this contribution, we propose a catalogue-based search for sub-TeV neutrino counterparts to sub-threshold GWs. For this search, we use archival data from IceCube’s dense-infill array, DeepCore. Using the unbinned maximum likelihood method, we search for a correlation between IceCube sub-TeV neutrinos and ~100 most significant sub-threshold GW source candidates. With this study, we aim to contribute to the ongoing efforts to identify common astrophysical sources of neutrinos and GWs. We present the current status of this search and its role in advancing multi-messenger astronomy, paving the way for a deeper exploration of GW events and their sources.

Speaker: Tista Mukherjee (Karlsruhe Institute of Technology)

18:05 Pre-merger alert to detect the very-high-energy prompt emission from binary neutron-star mergers: Einstein Telescope and Cherenkov Telescope Array synergy

The Einstein Telescope (ET), the third generation of gravitational wave detector is aimed at advancing multi-messenger astrophysics with strong synergy between current and future generation electromagnetic follow-up facilities, focusing mainly on the transients. Typically, the prompt emission from Gamma-ray bursts (GRBs) is observed within the 10 keV-10 MeV spectrum. However, detection at higher energies remains challenging. Although current very-high-energy (VHE; E > 30 GeV) gamma-ray detectors, such as MAGIC and H.E.S.S., have successfully detected GRB afterglows, the prompt detection phase has yet to be explored. This study explores the potential of multi-messenger observations to capture the prompt emission of short GRBs at TeV energies. Assuming binary neutron star mergers as progenitors of short GRBs, we assess the combined detection efficiency of the Cherenkov Telescope Array Observatory (CTAO) in conjunction with third-generation gravitational wave detectors. Our evaluation considers the capabilities of these facilities to detect and localize gravitational wave events already during the inspiral phase and issue early alerts to discover the prompt VHE emission. We show that the sensitivity of CTAO will make the detection of VHE emission feasible even if the emission is significantly fainter than that observed in the 10 keV–10 MeV range with telescopes such as Fermi/GBM. We discuss the implications within potential scenarios for prompt VHE counterparts of binary neutron star mergers, such as synchrotron self-Compton components within the leptonic framework, high-energy extensions of the hadronic GRB model, and external inverse Compton emission.

Speaker: Biswajit Banerjee

18:20 Astro-COLIBRI: A Comprehensive Platform for Real-Time Multi-Messenger Astrophysics

The detection of transient phenomena such as Gamma-Ray Bursts (GRBs), Fast Radio Bursts (FRBs), stellar flares, novae, and supernovae—alongside novel cosmic messengers like high-energy neutrinos and gravitational waves—has transformed astrophysics in recent years. Maximizing the discovery potential of multi-messenger and multi-wavelength follow-up observations, as well as serendipitous detections, requires a tool that rapidly compiles and contextualizes relevant information for each new event. We present Astro-COLIBRI, an advanced platform designed to meet this challenge.

Astro-COLIBRI integrates a public RESTful API, real-time databases, a cloud-based alert system, and user-friendly clients (a website and mobile apps for iOS and Android). It processes astronomical alerts from multiple streams in real time, filtering them based on user-defined criteria and placing them in their multi-wavelength and multi-messenger context. The platform offers intuitive data visualization, a quick summary of relevant event properties, and an assessment of observing conditions at numerous observatories worldwide.

In this contribution, we will highlight the key features of Astro-COLIBRI, describe its architecture and data resources, and showcase real-world applications. As examples we will illustrate its role in the search for high-energy gamma-ray counterparts to high-energy neutrinos, GRBs, and gravitational waves, demonstrating its impact on time-domain astrophysics.

Speaker: Dr Fabian Schüssler (IRFU / CEA Paris-Saclay)

17:05 → 18:35 NU: experimental & next generation

17:05 The GRAND@Auger Prototype for the Giant Radio Array for Neutrino Detection

As of early 2025, the GRAND collaboration has three prototype arrays in operation: GRANDProto300 in China, GRAND@Nançay in France, and GRAND@Auger in Argentina.The GRAND@Auger prototype was established through a collaboration between the GRAND and Pierre Auger Observatories, repurposing ten Auger Engineering Radio Array (AERA) stations into GRAND detection units. This setup provides a unique opportunity for coincident air-shower detection, enabling direct event-by-event comparison between GRAND@Auger and the well-established Pierre Auger detectors. These comparisons allow for a detailed assessment of the detection principle and the reconstruction capabilities of GRAND. In this contribution, we present an overview of the commissioning and preliminary results of GRAND@Auger, highlighting its role in advancing the GRAND project and refining the techniques required for large-scale radio detection of UHE particles.

Speaker: Prof. João de Mello Neto (Universidade Federal do Rio de Janeiro - UFRJ)

17:20 The Payload for Ultrahigh Energy Observations: Detector Design and Implementation

The Payload for Ultrahigh Energy Observations (PUEO) is slated to fly in December of this year out of McMurdo Station in Antarctica in search of the highest energy neutrinos produced in our Universe. PUEO is designed to detect Askaryan emission, a broadband radio signal that occurs when a neutrino interacts in a dense dielectric medium like Antarctic ice. To achieve better sensitivity than ANITA, its predecessor, PUEO has redesigned its antennas and trigger to benefit from the advanced beamforming capabilities of the RF-System on Chip (RFSoC).

PUEO will fly with two instruments: the main instrument, targeting the Askaryan emission from ultra-high energy neutrino flux, and the low frequency instrument, targeting radio emission from air showers induced by cosmic rays and tau neutrinos. Each detector is being carefully designed and modeled to maximize the potential sensitivity to these cosmic events.

In this contribution, I will discuss the status of the PUEO instrument, which is currently undergoing integration and testing in advance of its upcoming 30-day mission. In particular, I will present our current expectations for hardware performance, our implementation of the drop-down low frequency instrument, and our final areas of development prior to the flight. Finally, I will report on our simulation package, PUEOSim, and our progress towards modeling our instrument to prepare for both PUEO's launch and for future analyses.

Speaker: Kaeli Hughes (The Ohio State University)

17:35 Probing ultra-high-energy neutrinos with the IceCube-Gen2 in-ice radio array

The next generation neutrino telescope, IceCube-Gen2, will be sensitive to the astrophysical and cosmogenic flux of neutrinos across a broad energy range, from the TeV to the EeV scale. The planned design includes 8 cubic kilometers of ice instrumented with approximately 10,000 optical sensors, a surface array, and a radio array of antennas embedded in the ice laid out sparsely over 500 km^2. The radio array provides sensitivity to ultra-high energy neutrinos using independent radio stations that can trigger on Askaryan emission from neutrino interactions in the ice. In this contribution, we present the design for the radio array along with its planned implementation, which is expected to increase sensitivity to neutrinos with energies beyond 100 PeV by at least an order of magnitude over existing arrays. Furthermore, we will quantify the expected science output by presenting measurement forecasts for the main science cases of diffuse flux and point source discovery, as well as cross-section and flavor measurements.

Speaker: Christian Glaser (Uppsala University)

17:50 Prospects for Observing KM3NeT/ARCA-like Events from Astrophysical Transients with PBR

POEMMA-Balloon with Radio (PBR) is a scaled-down version of the Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) design, optimized to be flown as a payload on one of NASA's sub-orbital super pressure balloons circling over the southern oceans for a mission duration of as long as 50 days. One of the main science objectives of PBR is to follow up astrophysical event alerts in search for neutrinos of very high energy ($10^8 \lesssim E_\nu /{\rm GeV} \lesssim 10^{10}$). Of particular interest for anticipated PBR observations, the KM3NeT Collaboration has recently reported the detection of the neutrino KM3-230213A with $10^{8.1} \lesssim E_\nu/{\rm GeV} \lesssim 10^{8.9}$. Such an unprecedented event is in tension with 90\% CL upper limits on the cosmic neutrino flux from IceCube and the Pierre Auger Observatory, unless it was produced by a transient activity in its source. We calculate the PBR horizon-range sensitivity to expose a population of similar bursting sources in the Universe. We also consider the possibility that the KM3NeT/ARCA event was produced by the decay of superheavy dark matter broadly distributed in the Galactic halo.

Speaker: Angela V. Olinto (Columbia University)

18:05 Tracing Out The Neutrino Sky With TAMBO

Traditional searches for neutrino point sources have been hindered by the look-elsewhere effect. To address this, TAMBO will generate a catalog of neutrino source localizations - each localization equivalent in size to the square of TAMBO’s angular resolution. In doing so, TAMBO will have significantly reduced the available space to be searched by neutrino observatories, thus decreasing the trials factor necessary to elevate a local significance to a global one. In this talk we will present projected sensitivities to various neutrino sources and the effect of a TAMBO event to neutrino source discovery in IceCube. By refining the search through precise source localizations, TAMBO enhances the detection capabilities of observatories like IceCube, paving the way for efficient identification and confirmation of neutrino sources.

Speaker: Prof. Carlos Arguelles (Harvard University)

18:20 The recent status of the HUNT prototypes

To optimize the design of High Energy Underwater Neutrino Telescope (HUNT) project, we have already almost finished the development of a super large Optical Module（OM）with 20 inch PMT and LED calibration module. Since 2023, we successfully deployed some prototypes in Lake Baikal and the South China sea respectively. This report will present the specific design of OM and LED module, and show some operation results of these prototypes.

Speaker: Zongkang Zeng

17:05 → 18:35 NU: highlights & analysis

17:05 KM3NeT/ARCA Stacking Search for Ultra-Luminous Infrared Galaxies

KM3NeT/ARCA is a Cherenkov neutrino telescope currently under construction in the Mediterranean Sea, at 100 km off the Sicilian coast, near Capo Passero, and at about 3500 m depth.
On its final configuration, the detector will consist of a cubic kilometer volume of seawater instrumented with light detectors. Now, 33 detector units have been already deployed and are taking data. In this contribution, we search for neutrinos from a catalogue of 75 Ultra-Luminous Infrared Galaxies (ULIRGs), considering the latest experiment data. We not only perform a single source search along the catalogue but also conduct a binned likelihood stacking search. We present our unblinded results compared with the latest theoretical predictions from these sources discussing their role as potential neutrino emitters. We also exploit these results to quantitatively constrain the
entire source population contribution to the diffuse neutrino flux measured by the IceCube collaboration.

Speaker: Antonio De Benedittis (INFN - National Institute for Nuclear Physics)

17:20 Search for High-Energy Neutrinos from Infrared Flares

IceCube has detected a diffuse flux of high energy neutrinos, with the only two high-confidence extragalactic sources identified to-date being the accreting supermassive black holes (SMBHs) TXS0506+056 and NGC1068. This suggests that other SMBHs may also contribute to the observed neutrino flux. It is possible that some fraction of the IceCube neutrinos originate in time-variable SMBH accretion events. Candidate sources include AT2019dsg, which is likely a stellar tidal disruption event (TDE), and AT2019dfr, an AGN flare. Both present delayed emission in the IR band with respect to the optical signal. This emission can be interpreted as the reprocessing of X-rays to optical light of the flare by dust located in a torus around the SMBH. An additional study using an optically detected sample of 63 accretion flares revealed another candidate as a potential high-energy neutrino counterpart: AT2019aalc, which is also accompanied by a dust echo. However, follow-up stacking analysis of the 63 nuclear flares using the full IceCube data sample did not show any significant excess over background. Motivated by these three suggested neutrino-TDE correlations, we analyze a more extensive catalog of IR flares, 823 dust-echo-like flares identified using WISE satellite data, against the IceCube 10-year sample of track events from the Northern Sky. Our analysis aims to perform sensitivity studies and assess the potential detectability of neutrino emission from these types of accretion flares. In addition, we carry out a correlation study of the 823 dust echo-like flares against a revised catalog of IceCube high-purity astrophysical alerts, and reevaluate the previous study of 63 nuclear flares against the same revised alerts sample.

Speaker: Giacomo Sommani (Ruhr-Universität Bochum)

17:35 Search for Correlations of High-Energy Neutrinos with Infrared Flares in AGNs

The IceCube Neutrino Observatory issues real-time high-energy neutrino alerts and has released its first catalog (IceCat-1). However, the origin of these high-energy neutrinos remains largely unknown. Active galactic nuclei (AGNs) with variability are promising candidate sources. Previous studies have suggested a temporal correlation between high-energy neutrino alerts and infrared flares. In this contribution, we perform a spatial and temporal correlation analysis between a sample of AGNs (selected from the AllWISE catalog and cross-matched with the fourth Fermi-LAT catalog) in the infrared band and the latest IceCube high-energy neutrino alerts. Additionally, we investigate the multi-wavelength behavior of promising source candidates, from radio to γ-rays. We will present the results of these searches.

Speaker: Wenlian Li (1.State Key Laboratory of Dark Matter Physics, Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai 201210, China 2.Fakultät für Physik & Astronomie, Ruhr-Universität Bochum, 44780 Bochum, Germany)

17:50 Fast Radio Burst Sources and Neutrinos

The KM3NeT experiment is a next-generation neutrino telescope and particle physics detector, consisting of the ORCA and ARCA detectors, organised as 3D arrays of light sensors, and immersed in the depths of the Mediterranean Sea. Identical in their design but differing in scale, ORCA aims at detecting neutrinos in the GeV-TeV range, while ARCA will focus on higher energies in the TeV-PeV range. Both detectors can contribute to the study of astrophysical multi-messenger phenomena. Among the latter, Fast Radio Bursts (FRB) sources are good candidates for multi-messenger emissions due to the huge energy involved in their bursts. However, neutrino emissions from FRB sources are poorly constrained by models, which do not exclude temporal coincidences and motivate a search across both detector energy ranges. In this contribution, I will present the results of a multi-messenger analysis intended to search for spatial and temporal coincidences of astrophysical neutrino signals from the ARCA and ORCA detectors with FRBs. Sources were selected from several published FRB catalogues, taking into account the date and location of the observed bursts. The results of the correlation search conducted in KM3NeT for more than 250 FRBs is provided, setting a limit on the neutrino fluxes for each source.

Speaker: Félix BRETAUDEAU

18:05 Search for GeV-PeV neutrinos from nova T Coronae Borealis with IceCube

The widely anticipated outburst of recurrent nova T Coronae Borealis (T CrB), which is near the end of its 80-year cycle, provides an excellent opportunity to search for neutrinos from novae. Novae are an energetic class of transients, which have been studied for hundreds of years. Because many of them are located nearby, novae provide an excellent astrophysical laboratory to study shock-powered emission in our own backyard. Several recent novae have previously been detected in GeV gamma rays, and the 2021 outburst of RS Ophiuchi was detected up to TeV energies, with evidence for a hadronic origin of the observed emission. Previous searches for GeV-TeV neutrinos from novae, predicted to occur alongside their gamma-ray emission, have been performed using data from the IceCube Neutrino Observatory. However, no significant neutrino signals from novae have yet been observed. We present plans for follow-up of T CrB in real time with IceCube, using datasets spanning GeV to PeV neutrino energies. Due to its closer distance and higher optical flux, which has been well measured in two historical eruptions, the expected neutrino signal from T CrB is several times stronger than that from RS Ophiuchi. Furthermore, T CrB is located in the Northern sky at a declination where IceCube’s sensitivity is an additional factor of a few better than at the location of RS Ophiuchi, which is beneficial to this search.

Speaker: Justin Vandenbroucke (University of Wisconsin – Madison)

18:20 A Search for Astrophysical Neutrinos from Flaring X-ray Binaries with IceCube

Recently, IceCube has observed an excess of astrophysical neutrinos from the Galactic plane. Such a signal may indicate the presence of individual sources or a diffuse neutrino flux from the interactions of local hadronic cosmic rays. We consider the prospect of neutrino production in galactic X-ray binary systems. A model for neutrino production in the variable jets of these systems is discussed, and how such information may be incorporated within searches for astrophysical neutrinos. Two ongoing studies are presented on behalf of the IceCube Collaboration using 13 years of cascades and track-like events. In the first study, recently published model predictions are used to motivate the analysis of five selected black-hole X-ray binaries. Gamma-ray data from Fermi-LAT, as well as X-ray data from Swift/BAT and MAXI are used to search for temporal correlations between radiative cycles of the disk-jet system and potential neutrino emission. In the second study, a wider selection of variable X-ray binaries and their Swift/BAT light curves are considered and a stacking search is used to constrain the contribution of this source population to the Galactic neutrino flux.

Speaker: Alina Kochocki (Michigan State University)

Tuesday 22 July

08:30 → 09:00 Registration

09:00 → 10:30 Plenary session

09:00 The First Chapters of Galaxy and Black Hole Build-up Revealed by JWST

The first deep images with the James Webb Space Telescope (JWST) have transformed our view of the Universe. From day one, JWST produced one surprise after another: from unexpectedly luminous candidate galaxies at z>10, to an abundant, new class of obscured black holes, to massive quiescent galaxies when the Universe was only 1-2 Gyr old. With its unparalleled imaging and spectroscopic capabilities, JWST immediately extended our cosmic horizon into uncharted territory, with galaxies spectroscopically confirmed to z~14 and candidates identified out to z~16, only ~250-300 Myr after the Big Bang. We are thus at the brink of finding the first galaxies that ended the cosmic Dark Ages and started the reionization of the Universe. Furthermore, a surprising number of galaxies show broad-line emission in the early Universe indicating a very rapid build-up of early black holes. This includes an enigmatic new population known as 'Little Red Dots', characterized by their compact morphology and extremely red rest-frame optical colors. In this talk, I will review how far we have come in understanding early galaxy and black hole build-up thanks to the revolutionary new data with JWST over the past ~3 years and discuss the implications for models of cosmic dawn.

Speaker: Pascal Oesch (University of Geneva, Department of Astronomy)

09:30 Highlights from the IceCube Neutrino Observatory

The IceCube neutrino observatory has been successfully operating in its full configuration for almost 15 years and is characterized by a remarkably high stability and uptime. During this time, it has made many groundbreaking observations, such as the first detection of a high-energy diffuse cosmic neutrino flux or, more recently, the identification of the AGN NGC1068 as a steady source of high-energy neutrino emission and the observation of neutrinos from the Milky Way. In this talk, new developments in these areas will be discussed and further highlights presented. The second part then looks at the ongoing developments at the South Pole with IceCube Upgrade and IceCube-Gen2 and discusses their potential for advancing neutrino and astroparticle physics.

Speaker: Alexander Kappes (University Münster)

10:00 Magnetized turbulent plasmas as high-energy particle accelerators

How magnetized turbulent plasmas can accelerate charged particles is a long-standing question dating back to the seminal work of Enrico Fermi in the late 1940s. Nowadays, it is often invoked to model the production of non-thermal particle spectra in a variety of astrophysical settings, including extreme, relativistic sources such as black hole accretion disks, pulsar wind nebulae, or relativistic jets from active galactic nuclei. This presentation will review recent progress in this area and propose a modern theoretical picture of the physics at play, which is supported by numerical simulations, and which can be seen as a generalization of the original Fermi scenario. It will then discuss some phenomenological consequences in high-energy multi-messenger astrophysics.

Speaker: Dr Martin LEMOINE (APC (CNRS - U. Paris Cite))

10:30 → 11:00 Coffee

11:00 → 12:00 Plenary session

11:00 axions - Jörg Jaeckel

11:30 Direct Detection of Dark Matter: Status, Challenges, and Future Prospects

The quest to uncover the nature of dark matter remains one of the central goals in astroparticle physics. A leading hypothesis is that dark matter is composed of new elementary particles, with possible masses and interaction cross sections spanning many orders of magnitude. Particles in the MeV to TeV mass range may leave observable signatures through rare scatters off atomic nuclei or electrons in ultra-sensitive detectors operated in deep underground laboratories. In this talk, I will present the current status of direct detection efforts, outlining the experimental principles and highlighting key recent results. I will survey the most promising detector technologies, discuss their scientific reach across different dark matter mass regimes, and examine how current and next-generation experiments aim to overcome remaining challenges.

Speaker: Laura Baudis (University of Zurich (CH))

12:00 → 13:20 Lunch

13:20 → 14:50 CRD: experimental results: techniques & ML applications

13:20 The Response of 3D Imaging BGO Calorimeter of DAMPE to TeV e^+/e^- in space

The DArk Matter Particle Explorer (DAMPE) is a space-borne experiment that indirectly searches for dark matter by measuring the high-energy cosmic ray electrons/positrons (CREs) and gamma rays. The key sub-detector of DAMPE is the Electromagnetic CALorimeter (ECAL), which is designed for precise energy measurement with a large dynamic range from 5 GeV to 10 TeV. The ECAL consists of 308 Bismuth Germanium Oxide (BGO) crystals with dimensions of 2.5 cm × 25 cm × 60 cm. Since its launch at the end of 2015, DAMPE has been operating smoothly for over 9 years, getting a significant dataset of CREs exceeding TeV energies. In this work, we introduce a new calibration method for the high dynamic range of the BGO calorimeter specifically for the TeV CREs, thereby optimizing the energy measurement for individual events. In addition, we study the behavior of CREs beyond TeV energies in the BGO calorimeter, focusing on their high-energy electromagnetic shower development, including the lateral shower shape and the longitudinal shower shape. We also demonstrate the study of the e/p separation capability beyond TeV energy range using shower development, which plays a major role in the DAMPE experiment to measure the cosmic ray electron flux accurately.

Speaker: Ms Cong Zhao (University of Science and Technology of China)

13:35 Machine Learning methods for antideuteron identification with the AMS-02 detector

Cosmic ray antideuterons, although yet to be detected in space, represent a highly sensitive channel for probing new physics, including models related to Dark Matter. Their flux is expected to be approximately $10^{-9}$ times lower than that of protons posing significant challenges to their detection. The AMS-02 experiment, after 11 years of data collection, holds the potential for cosmic-ray antideuteron identification. However, the accurate characterisation and rejection of multiple backgrounds is crucial to achieve a good isotopic mass separation over a wide range of energies.
Machine Learning methods, particularly Boosted Decision Trees, are well suited for this classification task, but their performance relies on the choice of the features needed for their training phase. I explore both physics-driven feature selection methods and automated feature selection methods, based on Machine Learning algorithms, to optimise the classifier performance. I apply this enhanced feature selection methodology to the analysis of antideuteron identification in AMS-02 data, obtaining high background rejection while preserving 90% signal efficiency.

Speaker: Marta Borchiellini (Nikhef National institute for subatomic physics (NL))

13:50 Monte Carlo Helium Data Analysis for the ISS-CREAM Instrument

The Cosmic Ray Energetics and Mass for the International Space Station (ISS-CREAM) is designed to directly measure the energy spectra of high-energy cosmic rays, ranging from protons to iron nuclei, over the energy range of $\sim$$10^{12}$ to $\sim$$10^{15}$ eV. The goal of the instrument is to probe the origin, propagation and acceleration mechanisms of cosmic rays. The instrument comprises of a tungsten scintillating-fiber Calorimeter for energy measurements, four layers of finely segmented Silicon Charge Detectors for charge measurements, and two additional detectors for electron/hadron separation. The Calorimeter also provides the main high energy physics trigger, while the Top and Bottom scintillator-based counting detectors provide an additional low energy trigger. For consistency with the balloon-borne CREAM experiment analyses, the GEANT3 package with the FLUKA hadronic model was used for the simulations. The presented analysis focuses on isotropically generated helium nuclei events incident from the upper hemisphere onto the detector geometry. A comprehensive overview of the MC data analysis and its results, such as the detector efficiency, calorimeter energy response, position and charge resolutions, for the ISS-CREAM instrument will be presented.

Speaker: Arul Bagga (on behalf of the ISS-CREAM Collaboration) (Sungkyunkwan University)

14:05 A deep learning method for event recognition in CALET data

The Calorimetric Electron Telescope (CALET) is a powerful tool to observe cosmic-ray electrons between 1 GeV and 20 TeV. Its 30 radiation-length calorimeter enables total containment of electron-induced showers up to TeV energies, yielding an energy resolution of ~2% for these events. The CALET all-electron spectrum obtained using the first 7.5 years of data closely matches the one produced by the AMS-02, but DAMPE and Fermi-LAT are in tension in the 30 GeV - 20 TeV energy range. To investigate this tension, we developed an alternative classification method between electrons and protons using machine learning techniques instead of a deterministic algorithm. These unsupervised learning techniques are used to find clustering in the flight data events without training on simulated data. Here we present preliminary results from this analysis, and the performance of the trained method when applied to the simulated dataset.

Speaker: Adrien Picquenot

14:20 Unsupervised selection of cosmic-ray electrons and positrons in Fermi-LAT data

Measuring the energy spectrum of cosmic electrons and positrons in the GeV - TeV energy range can provide crucial evidence for the existence of local sources, whether of astrophysical or exotic nature. Over the past years, measurements from different experiments have reported significant discrepancies, particularly at TeV energies, where uncertainties become more pronounced.

The latest Fermi-LAT measurement, published in 2017, relied on an electron+positron selection using supervised Machine Learning methods. While effective, these techniques are inherently model-dependent, as they require training on Monte Carlo simulations, making them susceptible to systematic uncertainties and biases.

In this work, we introduce a novel approach based on Unsupervised Learning techniques, which can autonomously identify patterns within experimental data. This method enables an almost model-independent selection, reducing potential biases and enhancing the robustness of the analysis. The selection is applied to data collected with the Fermi Large Area Telescope, demonstrating the potential of Unsupervised Learning in astroparticle physics.

Speaker: Raffaella Bonino

14:35 GeoMagFilter: Modeling the Angular-Rigidity Joint Distribution of Galactic Cosmic Rays on Low Earth Orbit

We report the GeoMagFilter database for modeling the angular-rigidity joint distribution of galactic cosmic rays on low Earth orbit caused by the shielding of geomagnetic field and the Earth atmosphere. We use a backtracing software which integrates the particle trajectory with eight order Runge-Kutta algorithm in the geomagnetic field described by the IGRF13 model. At every 10 degree in longitude and 5 degree in latitude, backtracing is performed for 54 rigidities from 0.2 to 91.2 GV and 13963 arriving directions uniformly sampling the unit sphere. An altitude of 400 km and a latitude range of ±60 degree are used to cover the orbit of the International Space Station and the China’s Space Station. The detailed structures of the allowed cone, which is the arriving directions of galactic cosmic rays, are observed as a function of rigidity and geographic location. Comparisons of allowed cones are performed for understanding the impact from external geomagnetic field, variation of orbital altitude, evolution over time, and variation of particle flight time limit. Furthermore, the GeoMagFilter database is straightforwardly used in the precise calculation of radiation dose rate and orbit-averaged geomagnetic transmission function to account for the anisotropic distribution of the galactic cosmic rays on low Earth orbit.

Speaker: Dr Ran Huo (Shandong Institute of Advanced Technology)

13:20 → 14:50 CRI: space experiments

13:20 Five Years of Mini-EUSO Observations from the ISS: Summary of Key Results

Mini-EUSO is the first space-borne detector of the JEM-EUSO (Joint Exploratory Missions for Extreme Universe Space Observatory) program, operating on the International Space Station (ISS) since October 2019. Mounted on the Zvezda module, Mini-EUSO observes the Earth's atmosphere through a nadir-facing UV-transparent window. The size of this window determines the optical system, which consists of two 25 cm diameter Fresnel lenses. The main camera features an array of Multi-Anode Photomultiplier Tubes (MAPMTs) arranged in a 48×48 pixel matrix, mostly sensitive to the near-ultraviolet (290-430 nm band). The instrument’s 44°×44° field of view corresponds to a 300 km × 300 km area on the ground, with a pixel resolution of ~6 km.
Mini-EUSO unique acquisition system allows it to observe the Earth's atmosphere simultaneously on three different timescales, with time resolutions of 2.5 μs, 320 μs, and 40.96 ms. Designed to search for Ultra-High Energy Cosmic Rays (UHECRs) above $10^{21}$ eV and capable of placing a stringent upper limit on their flux at these extreme energies, paving the way to future space-based UHECR observatories, Mini-EUSO has completed nearly 150 observation sessions over five years, accumulating approximately 750 hours of data. The mission has produced the first global UV emission maps of Earth and provided valuable insights into lightning phenomena and Transient Luminous Events (TLEs), such as elves, as well as artificial light sources and meteors. Notably, Mini-EUSO has conducted the first systematic space-based meteor survey, detecting over 22,000 meteors and identifying three interstellar candidates.
Among the observed TLEs, the most interesting class of phenomena are elves, that appear as expanding ring-shaped structures occurring at ~90 km altitude. Mini-EUSO has detected elves with varying structures and different numbers of concentric rings, from single-ring up to five rings. Thanks to its imaging capabilities, fast time resolution, and favorable observational geometry, Mini-EUSO is uniquely suited to studying this kind of lightning phenomena, providing unprecedented insight into their dynamics.
Additionally, the instrument has demonstrated the capability of a space-based detector to identify short light transients resembling extensive air shower signals while distinguishing them from those produced by UHECRs.
This contribution presents a comprehensive summary of the MINI-EUSO mission, its status, and main results.

Speaker: Matteo Battisti

13:35 From Ground to Space: An Overview of the JEM-EUSO Program for the Study of UHECRs and Astrophysical Neutrinos

The JEM-EUSO (Joint Exploratory Missions for Extreme Universe Space Observatory) collaboration is an international initiative studying ultra-high-energy cosmic rays (UHECRs) and related phenomena. These particles, with energies exceeding 10$^{20}$ eV, provide insights into extreme astrophysical processes but remain challenging to detect due to their low flux.

At the heart of JEM-EUSO's technology is an ultra-fast, highly sensitive UV camera capable of detecting extensive air showers (EAS) in the atmosphere with exceptional spatial and temporal resolution.
In addition, a dedicated Cherenkov camera has been developed to evaluate the viability of the Earth-skimming technique from high altitudes. Fluorescence and Cherenkov detectors can be used together to create a hybrid detection surface, enhancing observational capabilities. This innovative approach enables detailed studies of fluorescence and Cherenkov light from cosmic ray and neutrino interactions. The JEM-EUSO technology will allow for observations from space to significantly increase the exposure to these rare phenomena.

The collaboration employs a multi-platform strategy—with ground-based experiments like EUSO-TA calibrating detection systems and validating models, and balloon-borne missions such as EUSO-Balloon and EUSO-SPB1/SPB2 demonstrating observations from the stratosphere and testing advanced technologies. Space-based missions, particularly Mini-EUSO on the ISS, have provided valuable data on UV backgrounds, transient luminous events, and meteoroids, as well as demonstrating the potential for future space-based detection. While we are developing a cross-platform methodology, we are ultimately moving towards space-based measurements. Future efforts include the POEMMA space mission, designed for stereoscopic observations of UHECRs and multi-messenger phenomena, and the PBR (POEMMA Balloon with Radio) experiment, which integrates radio detection and is scheduled to fly in 2027. Associated experiments also explore meteoroids, nuclearites, and strange quark matter, broadening the scientific scope.
This presentation will summarize the progress of the JEM-EUSO collaboration, highlighting achievements across all platforms and outlining future plans.

Speaker: Zbigniew Plebaniak (INFN Rome and University of Rome, Tor Vergta, Italy)

13:50 POEMMA-Balloon with Radio: An Overview

The POEMMA-Balloon with Radio (PBR) is a Ultra Long Duration Balloon payload scheduled for launch in Spring 2027 from Wanaka, New Zealand. It will circle over the Southern Ocean for a mission duration as long as 50 days, serving as a precursor to the dual satellite mission, Probe of Extreme Multi-Messenger Astrophysics (POEMMA). The PBR mission represents a significant step towards establishing a space-based multi-messenger observatory.
Observations from space will enhance the statistics of the highest-energy cosmic rays and complement ground-based observatories by enabling simultaneous observations of both hemispheres with a single instrument. Additionally, POEMMA will facilitate the measurement of Very-High-Energy Neutrinos (VHENs) following multi-messenger alerts of astrophysical transient events, such as gamma-ray bursts.
PBR is an adaptation of the POEMMA mission, featuring three primary science goals:

1. Observe Ultra-High-Energy Cosmic Rays (UHECRs) via the fluorescence technique from suborbital space.
2. Observe horizontal high-altitude air showers (HAHAs) with energies exceeding the cosmic ray knee (E > 3 PeV) using optical and radio detection for the first time.
3. Follow astrophysical event alerts in the search for VHENs.

This contribution provides an overview of the PBR payload and discusses the expected performance of its various detectors.

Speaker: Johannes Eser (Columbia University)

14:05 Implications of Mini-EUSO measurements for a space-based observation of UHECRs

Mini-EUSO is the first mission of the JEM-EUSO program on board the
International Space Station. It was launched in August 2019 and it is operating since October 2019 being located in the Russian section (Zvezda module) of the station and viewing our planet from a nadir-facing UV-transparent window. The instrument is based on the concept of the original JEM-EUSO mission and consists of an optical system employing two Fresnel lenses of 25 cm each and a focal surface composed of 36 Multi-Anode Photomultiplier tubes, 64 channels each, for a total of 2304 channels with single photon counting sensitivity and an overall field of view of 44×44◦. Mini-EUSO can map the night-time Earth in the near UV range (predominantly between 290 nm and 430 nm), with a spatial resolution of about 6.3 km and different temporal resolutions of 2.5 𝜇s, 320 𝜇s and 41 ms. Mini-EUSO observations are extremely important to better assess the potential of a space-based detector in studying Ultra-High Energy Cosmic Rays (UHECRs) such as K-EUSO and POEMMA. In this contribution we focus the attention on the results of the UV measurements and we place them in the context of UHECR observations from space, namely the estimation of exposure.

Speaker: Mario Edoardo Bertaina

14:20 EUSO-SPB2 Cosmic Ray Searches and Observations

The Extreme Universe Space Observatory on a Super Pressure Balloon 2 (EUSO-SPB2) flew in May of 2023, marking an important step towards the observation of ultra-high-energy cosmic rays (UHECR) and neutrino-induced showers from space. The ultimate goal of this endeavor is to complement ground-based detectors and achieve unprecedented exposure and nearly uniform full-sky coverage at the highest energies, thereby enabling charged particle astronomy and enriching the multi-messenger approach to high-energy astrophysics and astroparticle physics. As a pathfinder to the POEMMA mission (Probe Of Extreme Multi-Messenger Astrophysics), EUSO-SPB2 flew two distinct cameras at the focus of two Schmidt telescopes, one made of multi-anode photomultiplier tubes (MAPMTs), looking towards the nadir for fluorescence light detection, the other made of Silicon photomultipliers (SiPMs), looking towards the limb of the Earth for direct Cherenkov light detection. The flight was terminated prematurely due to a failure in the balloon, and thus no showers were detected in the fluorescence mode. However, several lower-energy (PeV scale) cosmic-ray events were observed in the Cherenkov channel. The data collected by both telescopes also confirmed the pertinence and maturity of the technology. We will report on the mission's cosmic ray results, and lessons learned for future balloon and satellite missions, notably the POEMMA Balloon with Radio (PBR), currently under development.

Speaker: George Filippatos

14:35 The Terzina payload on board the NUSES space mission

The Terzina payload on board the NUSES space mission is being built in collaboration with TAS-I by GSSI, INFN and the University of Geneva. It is a Cherenkov Schmidt-Cassegrain compact telescope with effective focal length of 925 m and a camera focal assembly composed of 640 pixels (16 vertically x 40 horizontally) organized in 8x8 tiles produced by FBK with sensitive area 2.73 x 2.34 mm^2.
Terzina is a technological pathfinder for larger missions dedicated to the future of ultra-high-energy studies of cosmic rays and earth-skimming astrophysical neutrinos beyond 100 PeV. We will illustrate the performance for the signal of cosmic rays beyond a threshold of few hundreds of PeV. Understanding the operation of SiPMs in space with almost direct exposure to solar and trapped protons and electrons, defining the mitigation strategy for the increase of dark count rate of exposed silicon, the measurements in situ of the luminous backgrounds, the data acquisition strategy for this payload, the maximization of the effective exposure to the atmospheric showers induced by the signal of neutrinos and cosmic rays are the challenges now at a good stage of readiness for the flight in 2026.

Speaker: Prof. Teresa Montaruli (Universite de Geneve (CH))

13:20 → 14:50 DM: axions

13:20 Search for heavy axions with the European X-Ray Free Electron Laser

When the Peccei-Quinn symmetry breaks after inflation, domain walls will form at the QCD scale in the axion field if there is more than one quark charged under the symmetry (as in e.g. the DFSZ model). When destabilised by quantum gravity effects, the collapse of the wall network creates relativistic axions, which subsequently turn non-relativistic and contribute to cold dark matter. Accounting for this additional contribution then requires the axion to be heavier than ~10 meV - a mass range that is little explored experimentally. We describe first results from a new light-shining-through-walls search for such heavy axions at the EuXFEL, Hamburg.

Speaker: Prof. Subir Sarkar (University of Oxford)

13:35 Probing axionlike particles with invisible neutrino decay using the IceCube observations of NGC 1068

In the beyond Standard Model (BSM) scenarios, the possibility of heavier neutrinos decaying into a lighter state is one of the prime quests for the new-generation neutrino experiments. The observation of high-energy astrophysical neutrinos by IceCube opens up a new avenue for studying neutrino decay. In this talk, I will discuss a novel scenario of invisible neutrino decay to axionlike particles (ALPs). These ALPs propagate unattenuated and reconvert into gamma rays in the magnetic field of the Milky Way. By exploiting the Fermi-LAT and IceCube observations of NGC 1068, we set 95% confidence level (C.L.) constraints on the coupling constant $g_{a\gamma}$ ≤ 1.37 x 10$^{−11}$ GeV$^{−1}$ for ALP masses $m_a$ ≤ 2 x 10$^{−9}$ eV. Finally, I discuss the contribution of NGC 1068-like sources to diffuse gamma-ray flux at GeV energies under the ALP scenario.

Speaker: Bhanu Prakash Pant

13:50 Search for Axion-like Particles Using TeV Blazar Observations with the HAWC Observatory

Axion-like particles (ALPs) are hypothetical pseudoscalar particles predicted in several extensions of the Standard Model. These particles have the potential to address both the dark matter problem and the strong CP problem. One method to detect ALPs is through the phenomenon of ALP-photon oscillation in the presence of magnetic fields. In high-energy astrophysics, ALP-photon oscillation can manifest as an increased transparency of TeV gamma rays from extragalactic sources.

In this work, we present a search for ALPs using gamma-ray observations of three TeV blazars, obtained with the High-Altitude Water Cherenkov (HAWC) Observatory. For each blazar, we calculate the photon survival probabilities across different regions of the ALP parameter space, assuming both the presence and absence of ALPs. By fitting the expected spectra of these two scenarios and comparing the resulting likelihoods, we establish upper limits on the parameters of ALPs. We present new constraints on the coupling strength between ALPs and photons for ALP masses in the neV range.

Speaker: Ian James Watson (University of Seoul)

14:05 Detecting axion star mergers in the pi-axiverse

With the WIMP parameter space slowly being ruled out by experiments on all fronts, axions have become a highly studied alternative dark matter candidate. In this talk we present a particle physics model where the pion states of a dark copy of QCD have both axion and dilaton phenomenologies. This model allows for the formation of dilute axion stars over a far larger parameter space than allowed in typical axion models. We explore whether such a model could be detected via FRB-like emissions associated with stable axion star mergers, these have unique broad spectra (rather than axion lines). We demonstrate that strong detection prospects exist for these events with both MeerKAT and upcoming experiments like the SKA and ngVLA.

Speaker: Geoff Beck

14:20 Do axions put out gamma-ray bursts?

Short gamma-ray bursts (GRBs) are some of the brightest transients in the universe. Heavy axion-like particles (ALPs) can be produced in the hot plasma of GRB fireballs and escape, transporting energy away the from the source. When they decay outside the source, we show that the resulting photon field is too rarefied to re-thermalize, effectively preventing the re-emergence of the fireball, thus dimming or disrupting GRBs. Using existing observations of short GRBs, we place competitive bounds reaching ALP-photon couplings of $g_{a \gamma \gamma} \sim 4 x 10^{-12}~\text{GeV}^{-1}$ for ALP masses between 200 MeV and 5 GeV.

Speaker: Oindrila Ghosh (Stockholm University & the Oskar Klein Centre)

14:35 Novel bounds on decaying axionlike particle dark matter from the cosmic background

The cosmic background (CB) is defined as the isotropic diffuse radiation field with extragalactic origin found across the electromagnetic spectrum. Different astrophysical sources dominate the CB emission at different energies, such as stars in the optical or active galactic nuclei in x rays. Assuming that dark matter consists of axions or axionlike particles with masses on the order of electron volts or higher, we expect an additional contribution to the CB due to their decay into two photons. Here, we model the CB between the optical and x ray regimes, and include the contribution of decaying axions. Through a comparison with the most recent direct and indirect CB measurements, we constrain the axion parameter space between masses $0.5 \mathrm{eV} - 10^7\mathrm{eV}$ and improve previous limits on axion-photon coupling derived from the CB by roughly an order of magnitude, also reaching the QCD band. We further study the contribution of axions decaying in the Milky Way halo and characterize the axion parameters that would explain the tentative excess CB emission observed with the Long Range Reconnaissance Imager instrument on-board the New Horizons probe.

Speaker: Sara Porras Bedmar (Universitaet Hamburg)

13:20 → 14:50 GA: galaxies & clusters

13:20 High-energy Neutrino and Gamma Ray Emission from Clusters-like Perseus

We calculate the high-energy gamma-ray and neutrino emissions from galaxy clusters like Perseus that host active galactic nuclei (AGNs). Our primary objective is to distinguish the emission from the central source, such as NGC1275, from the diffuse emission originating in the outskirts of the Perseus cluster. Due to unique magnetic-field configuration, CRs with energy ≤ 10^17 eV can be confined within these structures over cosmological time scales, and generate secondary particles, including neutrinos and gamma-rays, through interactions with the background gas and photons. We employ three-dimensional cosmological magnetohydrodynamical simulations of structure formation to model the turbulent intracluster medium (ICM). We propagate CRs in ICM and intergalactic medium using multi-dimensional Monte Carlo simulations, considering all relevant photohadronic, photonuclear, and hadronuclear interactions. We also include the cosmological evolution of sources like Perseus. By comparing our results with the existing upper limits from IceCube for galaxy clusters and the sensitivity of CTA, we predict that these observatories could potentially establish a new class of astrophysical sources capable of emitting high-energy multi-messenger signals. We also compute the contribution from clusters like Perseus to the diffuse neutrino and gamma-ray background.

Speaker: Saqib Hussain

13:35 Search for cosmic-ray induced gamma-ray emission from local galaxy clusters using Fermi-LAT data

Galaxy clusters are the most massive gravitationally bound structures in the Universe. Even if clusters are nearly virialized structures, they undergo merging processes, creating merging shocks, and suffer from feedback from galaxies and AGNs; causing complex turbulent motions and amplifying their magnetic fields. These processes act as acceleration mechanisms for the plasma of the intracluster medium (ICM), originating a population of cosmic rays (CRs). Leptonic CRs have been long detected, but we should also expect a CR hadronic population that, through interactions with the ICM, should produce neutral pions that decay into gamma-rays. The detection of diffuse gamma-ray emission from galaxy clusters is one of the long-awaited milestones for the high-energy astroparticle physics community. Still, no unambiguous detection has been yet obtained.
In this talk, we will present the results of a combined cluster analysis searching for CR-induced gamma-ray signals, using 16 years of Fermi-LAT data. In our previous work (di Mauro et al. 2023) we obtained from the combined analysis of 49 local galaxy clusters (12 years of data) a hint of signal between 2.5-3 sigmas, depending on the DM model considered. These results are aligned with the most recent works on searches for gamma-ray emission from clusters on Fermi-LAT data, which consistently find a non-vanishing hint of signal around the detection threshold. In this new work, we use a sample of near, well-known galaxy clusters and develop CR-induced emission templates using well-established X-ray measurements for calibration, assuming self-similarity for the members of our sample. To strengthen the robustness of our analysis, we define benchmark models to encapsulate the uncertainties in the spectral and spatial profiles for the CR-induced emission and perform the standard template-fitting analysis using the likelihood ratio test.

Speaker: Judit Pérez-Romero (Center for Astrophysics and Cosmology / University of Nova Gorica)

13:50 Searching for dark matter signatures in the Virgo Cluster with H.E.S.S.

In this contribution, we present a search for dark matter signatures from the Virgo Cluster using over 200 hours of observations with the H.E.S.S. Imaging Atmospheric Cherenkov Telescope Array. Galaxy clusters provide an ideal environment for investigating potential dark matter interactions, whether through particle decay or annihilation, which could generate a persistent flux of very-high-energy gamma rays, distinguishable from the hadronic background. The Virgo Cluster, due to its proximity and significant mass, stands out as a particularly promising target for such studies. We explore both decay and annihilation channels, assessing the influence of dark matter halo substructures on the expected signal.

Speaker: Jean-François Glicenstein (IRFU, CEA Paris-Saclay)

14:05 GeV-TeV Connections in Massive Galaxies: Pulsar-Driven Emission and Prospects for Evolutionary Insights

The dominant mechanisms underlying the high-energy gamma-ray emission from galaxies vary with galaxy types. In starburst galaxies, a substantial component arises from neutral pion decays. These are driven by interactions of hadronic cosmic rays (CRs) accelerated in strong shocks associated with the star formation process and its end-products. Leptonic gamma-rays may also originate from electrons directly energized by shocks within the interstellar medium of galaxies, from charged pion decays in hadronic interactions, or from pulsars and their surrounding halos. In more quiescent galaxies like the Milky Way, pulsars and their halos represent a major gamma-ray source class. These sources can contribute significantly to the high-energy galactic emission, with recycled millisecond pulsars predominantly located in globular clusters (GCs) being particularly important. Recent detections of very high-energy (VHE) emission from Galactic GCs suggests they may also contribute to the TeV gamma-ray flux from evolved galaxies. We consider a scenario where the VHE emission from GCs is driven by electrons accelerated in pulsar wind termination shocks, which undergo inverse Compton scattering as they propagate into GC magnetotails. We find that the high energy emission from these GCs could dominate the GeV and TeV flux from massive, quiescent galaxies, and show that the relationship between the GeV and TeV GC emission depends on the global galactic properties. In this contribution, we will demonstrate how GeV-TeV connections in massive galaxies can reveal new information about their formation history, and discuss how this can help to refine our understanding of how massive galaxies evolve.

Speaker: Ellis Owen (RIKEN)

14:20 Results from deep VERITAS observations of starburst galaxies

The growing number of starburst galaxies detected by the current generation of gamma-ray detectors has brought this class of objects to the forefront of cosmic-ray research. The VERITAS collaboration has performed very-high-energy (VHE; E>100 GeV) gamma-ray observations of a variety of starburst galaxies as part of a long-term program. The selection of these targets is based on either a high star-formation rate and central matter density, or a Fermi-LAT MeV-GeV gamma-ray detection. The VERITAS program has collected hundreds of hours of data over many years from more than 10 starburst galaxies, including the prominent VHE emitter, M82. Results from these extensive observation campaigns will be presented. By combining the VERITAS measurements with data from multiple instruments across the electromagnetic spectrum, an understanding of the underlying emission and transport processes will also be presented. These results also provide insight into observation strategies for the next generation of gamma-ray telescopes.

Speaker: Lab Saha

14:35 MWL study of OT 081 and other blazars on the border of categorization

The blazar OT 081 was detected only once in the very-high-energy gamma-rays range, by MAGIC and H.E.S.S. telescopes. The multiwavelength (MWL) data collected in that single opportunity, and reported in a recently published paper (Abe et al. 2025, "Multi-wavelength study of OT 081: broadband modelling of a transitional blazar"), show a challenging theoretical interpretation because of the high Compton Dominance of the MWL SED. In the flaring episode presented in Abe et al. 2025 moreover, the source, previously categorized as a BL Lac in several occasions, presents clearly characteristics of Flat Spectrum Radio Quasars. In this contribution we report the efforts in connecting the broadband model to the VLBI data, with two zone models that we also apply to a sample of candidate transitional blazars. The goal is to deepen our knowledge of blazars of controversial categorization.

Speaker: Marina Manganaro

13:20 → 14:50 GA: pulsars and halos

13:20 Detection of extended X-ray emission surrounding PSR B0656+14 with eROSITA

Extended very-high-energy gamma-ray emission from middle-aged pulsars as revealed recently by several groundbased gamma-ray experiments has strong implication on the transport of high-energy particles in the interstellar medium surrounding those pulsars. The gamma-ray emission is widely believed to be produced by high-energy electrons and positrons accelerated by the pulsar wind nebulae when scattering off the interstellar radiation field via the inverse Compton process. Multiwavelength counterparts of the γγ-ray halos are expected to be present, which are, however, not observed yet. In this work, we report for the first time the detection of extended X-ray emission from ~0.2 degree radius region of PSR B0656+14 with eROSITA. The spectrum of the emission can be described by a power-law function with an index of ∼3.7. The fluxes decrease with radius faster than the prediction of the particle diffusion and synchrotron radiation in a uniform magnetic field, suggesting the existence of a radial gradient of the magnetic field strength as r^{−1}. The magnetic field strength in the X-ray emitting region is constrained to be 4−10 μG.

Speaker: Qiang Yuan

13:35 Study of TeV halo candidate LHAASO J1849+0851 with LHAASO data

In this talk, we report the discovery of an extended very-high-energy (VHE) gamma-ray source around the location of the middle-aged (360 kyr) pulsar J1846+0919 with LHAASO. The source is detected with a significance of 7 σ for E>10 TeV assuming a Gaussian template. The best-fit position is (RA, Dec) = 281°.90±0°.21, 9°.44±0°.17, and the extension is 0°.88±0°.17. The spectrum can be described by a power-law with an index of 3.18±0.12. Given the absence of SNR couterparts and very similar age (360 kyr), spin-down luminosity (3.4e+34 ergs/s) and period (0.226 s) to the geminga pulsar (age = 340 kyr, Edot = 3.26e+34 ergs/s, P0 = 0.237 s), this source can be a promising halo candidate. Although the properties of the two PSRs are very similar, the physical size of this source is about twice that of geminga TeV halo.

Speaker: Shicong Hu (Institute of High Energy Physics, Chinese Academy of Sciences)

13:50 HESS J1831-098: Exploring a pulsar halo scenario with H.E.S.S. data

Pulsar halos are a recent class of extended very high-energy (VHE) sources discovered by the HAWC observatory towards the Geminga and Monogem pulsars. These VHE sources are interpreted as the inverse Compton emission from electrons and positrons diffusing in the interstellar medium at an inhibited rate, having escaped the pulsar wind nebula. Our aim is to search for new pulsar halos using Imaging Atmospheric Cherenkov Telescope data - in particular on sources from the H.E.S.S. Galactic Plane Survey - and to constrain their physical properties.
Using a physically-motivated model of pulsar halos, we created template-based models of the spatial and energetic distributions of the expected gamma-ray emission using the Gammapy library. Promising candidate sources to apply this model are extended VHE sources associated with energetic pulsars, some of which also exhibit spectral continuity and morphological compatibility with ultra-high-energy sources. One such source is HESS J1831-098, which is associated to 1LHAASO J1831-1007u and could be powered by the radio pulsar PSR J1831-0952 with a characteristic age of 128 kyr. We present a spectro-morphological analysis of this source with H.E.S.S. data revealing that the emission can be well described with a pulsar halo model and we discuss the implication of the derived physical parameters of the model.

Speaker: Karim SABRI

14:05 Geminga's pulsar halo: a multiwavelength view

Geminga is the first pulsar around which a remarkable TeV gamma-ray halo extending over a few degrees was discovered by MILAGRO, HAWC and later by H.E.S.S., and by Fermi-LAT in the GeV band. Similar emission has been detected for other middle-aged pulsars in their late evolution stages, and is most plausibly explained by inverse Compton scattering of CMB and interstellar photons by relativistic electrons and positrons. These observations pose a number of theoretical challenges. Tackling these questions requires constraining the ambient magnetic field properties, which can be achieved through X-ray observations. If gamma-ray halos originate from a distribution of highly energetic electrons, synchrotron losses in the ambient magnetic fields of the same particles are expected to produce a diffuse X-ray emission with a similar spatial extension.
In this contribution I will present the most comprehensive multi-wavelength study of the Geminga pulsar halo to date. In addition to gamma rays, we use archival X-ray data from XMM-Newton and NuSTAR, covering a broad bandwidth (0.5-79 keV) and large field of view (~4 degrees) for the first time. We find no significant emission and set robust constraints on the X-ray halo flux. These are translated to stringent constraints on the ambient magnetic field strength and the diffusion coefficient by using a physical model considering particle injection, diffusion and cooling over the pulsar's lifetime, which is tuned by fitting multi-wavelength data.
Finally, I will discuss the application of our novel methodology to the modelling and searching for synchrotron X-ray counterparts of other pulsar halo candidates.

Speaker: Dr Silvia Manconi (Sorbonne University & LPTHE, Paris)

14:20 TeV Emission from PSR B1055-52 with HESS: Evidence for a Pulsar Halo

Pulsar halos are a recently identified class of TeV γ-ray sources, offering valuable insights into the evolution of pulsar systems at the highest energies. However, only a handful of such sources have been detected so far, making each new identification critical for understanding the properties of the population as a whole. We report the first detection of extended very-high-energy (VHE) γ-ray emission around PSR B1055−52 using observations from the H.E.S.S. array. This middle-aged pulsar, previously grouped together with Geminga and PSR B0656+14 as part of the "Three Musketeers," has now been confirmed to host a TeV pulsar halo, making it the third detected system of its kind, and the first TeV pulsar halo discovered in the southern hemisphere. Our analysis performed in an energy range of 0.3–60 TeV, reveals gamma-ray emission with an one sigma extension of (1.92 ± 0.23)°. The analysis indicates that the emission extends beyond the region which was observed with H.E.S.S.. No significant spectral variation is detected across the emission.

The diffusion coefficient derived for this halo is significantly lower than the standard ISM value, aligning with findings in the Geminga halo and indicating that slow diffusion may be a common property of pulsar halos. The detection of this new TeV pulsar halo provides a crucial data point for studying the population-wide properties of pulsar halos, their impact on cosmic-ray propagation, and their role as a source of Galactic electrons and positrons.

Speaker: Tina Wach (Erlangen Centre for Astroparticle Physics (ECAP), Friedrich-Alexander-Universität Erlangen-Nürnberg)

14:35 A population study of PWNe/halos detected by LHAASO

A major fraction of gamma-ray sources in the non-thermal universe are pulsar wind nebulae (PWNe), which evolve rapidly and exhibit distinct morphological and spectral features at different evolutionary stages. LHAASO has identified dozens of TeV sources associated with pulsars, which are potential candidates for PWNe or halos. In this study, we use LHAASO data to investigate the relationship between the pulsars and the TeV emissions from their associated nebulae or halos, aiming to better understand the evolution of PWNe.

Speaker: Yu Luo (Shanghai Jiao Tong University)

13:20 → 14:50 NU: atmospheric interpretations & MM studies

13:20 A neutrino flux above 5 PeV and implications for ultrahigh-energy cosmic rays

The detections of rare events above 5 PeV by two neutrino telescopes highlights the existence of a neutrino flux at these energies. In over a decade of data taken by the IceCube Neutrino Observatory, three events were detected and reconstructed to have energies above 5 PeV. More recently, the KM3NeT neutrino telescope announced their detection of a possible O(100 PeV) neutrino candidate. The connection between the highest-energy neutrinos and cosmic rays is well established. Here, for the first time, we simultaneously fit the neutrino data from IceCube and KM3NeT, as well as the ultrahigh-energy cosmic ray spectrum and composition data from the Pierre Auger Observatory (Auger), to test a common-origin hypothesis. We show that a phenomenological model is able to describe the combined data across these three observatories, and, depending on the true energy of the event detected by KM3NeT, suggests an additional cosmic ray source population not yet robustly detected by Auger. Next-generation observatories, such as IceCube-Gen2, will have the sensitivity to make a significant detection of this flux.

Speaker: Tianlu Yuan (University of Wisconsin Madison)

13:35 Can KM3-230213A be compatible with a cosmogenic origin?

On the 13th February 2023 the KM3NeT/ARCA telescope observed a track-like event compatible with a ultra-high-energy muon with an estimated energy of 120 PeV, produced by a neutrino with an even higher energy, making it the most energetic neutrino event ever detected. The reported equivalent flux suggest the possible existence of a new diffuse component. A diffuse cosmogenic flux is expected to originate from the interactions of ultra-high-energy cosmic rays with ambient photon and matter fields. Here we show that this component can be compatible with the reported flux level only integrating the cosmogenic emission, at least up to redshift ~ 6 and assuming a subdominant fraction of protons in the ultra-high-energy cosmic-ray flux, thus placing constraints on known cosmic accelerators.
These conditions impose constraints on known cosmic accelerators and open a window into an unexplored region of the Universe at this energy scale.

Speaker: Antonio Marinelli (Università di Napoli, Federico II)

13:50 Interpretation of the KM3-230213A event origin in terms of extragalactic blazar sources

The KM3NeT infrastructure is constructing two Cherenkov Neutrino detectors in the Mediterranean Sea: ARCA, optimised for high-energy cosmic neutrinos and located at 3450 m depth near Sicily, and ORCA, designed for neutrino oscillation studies at 2450 m depth off Toulon. Though still under construction, KM3NeT detectors are operational. An extremely-high-energy neutrino (hundreds of PeV) referred to as KM3-230213A was detected by the 21 lines of the ARCA detector on 13, February 2024. This unique observation may offer new windows for very high energy neutrino astronomy and consequently deserves deep investigation.
In this contribution, we study if blazars, a specific class of Active Galactic Nuclei (AGN), might have powered the KM3-230213A event. We start by simulating the lepto-hadronic interactions for blazar models using the open-access Astro-Multimessenger Modeling Software (AM3). Then, we quantify the diffuse gamma-ray and neutrino emission exploiting the Fermi-LAT blazar luminosity function and perform a statistical analysis to constrain the source population parameter. We conclude by discussing the potential interpretation of this ultra-high-energy neutrino in the context of blazars.

Speaker: Meriem Bendahman

14:05 The blazar PKS 0605-085 as the origin of the KM3-230213A neutrino event

The origin of the remarkable ultra high energy neutrino event KM3-230213A observed with the ARCA detector is still unclear. In particular, most galactic scenarios are excluded, and a persistent isotropic source is disfavored due to the non-observation of a similar event by the IceCube detector. We show that the neutrino causing the KM3-230213A event could have been produced in the blazar PKS 0605-085 (redshift z = 0.87). This flat-spectrum radio quasar (FSRQ) is located at 2.4$^{\circ}$ from the reconstructed direction of the KM3-230213A event, allowing for an angular association between the blazar and the event in view of a sizable direction systematic uncertainty of 1.5$^{\circ}$ reported by the KM3Net Collaboration. FSRQs are believed to contain several distinct regions filled with photon fields external to the main relativistically moving particle acceleration zone (the "blob"), greatly boosting the neutrino production efficiency w.r.t. the synchrotron self-Compton (SSC) scenario. In particular, we consider a scenario where the external photon field is provided by the outer layer (the "sheath") of the "spine-sheath" jet structure, and particle acceleration occurs inside the same blobs that are responsible for the 2021-2023 gamma-ray flare of the blazar PKS 0605-085. Furthermore, we note that the X-ray and gamma-ray constraints on the produced neutrino intensity could be significantly relaxed in the framework of the external photon field scenario. We indicate a possible physical reason why the brightest blazar flares, notably from the blazar 3C 454.3, seem to be neutrino-dim. Following our previous work [A&A, 603, A59 (2017)]; [Phys. Rev. D, 102, 123017 (2020)]; [MNRAS, 505, 1940 (2021)]; [MNRAS, 527, L95 (2024)] we show that the intergalactic cascade gamma-ray counterpart of the KM3-230213A event is not observable by the existing gamma-ray telescopes in the considered scenario. Finally, we make a verifiable prediction that after the planned re-calibration of the ARCA detector the new, refined direction of the KM3-230213A event will point to the blazar PKS 0605-085. Some details of this work are available in astro-ph/2502.11434. This work is supported in the framework of the State project "Science" by the Ministry of Science and Higher Education of the Russian Federation under the contract 075-15-2024-541.

Speaker: Timur Dzhatdoev

14:20 Insights from leptohadronic modelling of the brightest blazar flare

The blazar 3C 454.3 experienced a major flare in November 2010 making it the brightest $\gamma$-ray source in the sky of the Fermi-LAT. Motivated by the $3\sigma$ association of a $\gtrsim 290$ TeV muon neutrino IceCube170922A with an electromagnetic flare in TXS 0506+056 and noting that 3C 454.3 was $\sim 100$ times brighter than TXS 0506+056, we enquire what level of the neutrino flux we could expect from the brightest blazar flare of 3C 454.3. We obtain seven daily consecutive spectral-energy distributions (SEDs) of the flare with publicly available multiwavelength data. We simulate the physical conditions in the blob during the flare and obtain a robust upper limit to the amount of high-energy protons in the jet of 3C 454.3 from the electromagnetic SED using the high statistics of X-ray data. We construct a neutrino light curve of 3C 454.3 and estimate the expected neutrino yield at energies $\geq 100$ TeV for 3C 454.3 to be up to $6 \times 10^{-3}$ muon neutrinos per year. We show that if the acceleration timescale for protons is as slow as for electrons the peak of the neutrino SED happens around 100 TeV - 1PeV. If protons have a more efficient acceleration, the peak energy of the neutrino SED can be as high as $\sim100$ PeV, similar to the energy of the recently discovered KM3-230213A neutrino. Finally, we extrapolate our model findings to the light curves of all Fermi-LAT flat-spectrum radio quasars. We find that next-generation neutrino telescopes are expected to detect approximately one multimessenger ($\gamma + \nu_{\mu}$) flare per year from bright blazars with neutrino peak energy in the hundreds TeV - hundreds PeV energy range and show that the electromagnetic flare peak can precede the neutrino arrival by months to years.

Speaker: Mr Egor Podlesnyi (Norwegian University of Science and Technology (NTNU))

14:35 Extreme Relativistic Beaming in Neutrino-Associated Blazars

Blazars have emerged as prominent sources of high-energy neutrinos, with multiple IceCube events linked to them in recent years. A growing body of observational evidence suggests that relativistic beaming is a crucial factor in neutrino emission from these extreme astrophysical accelerators. In this work, we conduct a statistical investigation of this connection by analyzing jet geometry, kinematics, and Doppler and Lorentz factors of neutrino-coincident blazars. These quantities are measured at parsec scales through VLBA observations within the MOJAVE program.
Additionally, we present a remarkable individual case of the blazar 1424+240, which is associated with one of the most significant peaks in the IceCube stacked neutrino all-sky map. Its VLBA polarization image, stacked over 20 years, reveals a jet observed from within its opening cone, maximizing relativistic beaming and reinforcing the link between neutrino production and jet orientation.
Our findings indicate that high-energy neutrinos are predominantly emitted along the jet’s axis, suggesting that their parent PeV-scale protons exhibit relativistic bulk motion. This implies that neutrino production occurs at sub-parsec scales, where the jet has already undergone substantial acceleration. These results offer a crucial insight into the physical conditions necessary for neutrino generation in blazars.

Speaker: Yuri Kovalev (Max Planck Institute for Radio Astronomy)

13:20 → 14:50 NU: highlights & analysis

13:20 A Global Strategy for The Future of High-Energy Neutrino Astronomy

The discovery of the first astrophysical sources of high-energy neutrinos by IceCube jump-started high-energy neutrino astronomy. To advance the field, we must increase the number of identified sources from a few to dozens. However, progress is currently limited by the relatively low detection rate of astrophysical neutrinos and restricted sky coverage of IceCube, the single kilometer-scale neutrino telescope in operation. Already today---thanks to KM3NeT and Baikal-GVD---and more so over the next 10--20 years, this challenge will be overcome by the combined observations of new neutrino telescopes, larger and distributed around the world. They will increase the global neutrino detection rate by up to 30 times and provide continuous all-sky coverage. Within the joint analysis framework of the Planetary Neutrino Monitoring network (PLE$\nu$M), we show how combining data from these telescopes will expedite source discovery---sometimes by decades---and enable the detection of fainter sources across the sky. High-energy neutrino astronomy is a global endeavor, and advancing it meaningfully will require a united global effort.

Speaker: Dr Mauricio Bustamante (Niels Bohr Institute)

13:35 Extending KM3NeT’s Point-Source Searches to Lower Energies with KM3NeT/ORCA

Neutrino telescopes play a key role in multi-messenger astrophysics, providing unique insights into the still-unclear processes in our Universe and its active sources.
With the goal of shedding light on these mysteries, the KM3NeT collaboration is deploying a deep-sea Cherenkov neutrino telescope in the Mediterranean Sea.
It comprehends two detectors: identical in their design but differing by scale. KM3NeT/ARCA, off the coast of Sicily, is optimized for high energies in the TeV-PeV range to observe astrophysical neutrinos. KM3NeT/ORCA, off the coast of Toulon (France), is designed primarily for detecting neutrinos in the GeV-TeV range and studying the neutrino mass ordering. However, KM3NeT/ORCA is also capable of detecting astrophysical neutrinos, extending KM3NeT’s reach to sources at energies lower than those observed by KM3NeT/ARCA.

In this contribution, we present point source analyses of the data collected by KM3NeT/ORCA from January 2020, when 6 detector lines were active, with an evolving detector geometry. For the first time, KM3NeT/ORCA data are used to perform a binned likelihood analysis, improving KM3NeT’s sensitivity to softer spectra and enabling the detection of neutrino sources across a wider energy range.

Speaker: Ilaria Del Rosso (University of Bologna, INFN-Bo)

13:50 Prospects for Observing Astrophysical Transients with GeV Neutrinos

Although Cherenkov detectors of high-energy neutrinos in ice and water are often optimized to detect TeV-PeV neutrinos, they may also be sensitive to transient neutrino sources in the 1-100~GeV energy range. A wide variety of transient sources have been predicted to emit GeV neutrinos. In light of the upcoming IceCube-Upgrade, which will extend the IceCube detector's sensitivity down to a few GeV, as well as improve its angular resolution, we survey a variety of transient source models and compare their predicted neutrino fluences to detector sensitivities, in particular those of IceCube-DeepCore and the IceCube Upgrade. We consider the ranges of neutrino fluence from transients powered by non-relativistic shocks, such as novae, supernovae, fast blue optical transients, and tidal disruption events. We also consider fast radio bursts and relativistic outflows of high- and low-luminosity gamma-ray bursts. Our study sheds light on the prospects of observing GeV transients with existing and upcoming neutrino facilities.

Speaker: ANGELINA PARTENHEIMER

14:05 KM3NeT’s sensitivity to the next core-collapse supernova

Core-collapse supernovae (CCSNe), the collapse of supermassive stars, have a significant impact on the dynamics of galaxies but their underlying mechanism is still only partially understood. These phenomena, however, produce short and extremely intense neutrino bursts, which could be used to probe the dynamics of the CCSN cores. However, such neutrinos would be detected only for CCSNe occurring in the Milky Way or its satellite galaxies, which occur around twice per century. It is therefore necessary to maximise the detection potential of all sensitive neutrino experiments, including very-large-scale water Cherenkov detectors, primarily aimed at GeV-PeV neutrino detection. In this contribution, we present a new CCSN search using the KM3NeT neutrino detector. In this search, we consider KM3NeT's Digital Optical Modules (DOMs) as standalone detectors for MeV-scale CCSN neutrinos. We define observables that characterize the pattern of activated photomultipliers on a single DOM, and use them to distinguish CCSN neutrinos from radioactivity and atmospheric muon backgrounds. With this search strategy, KM3NeT could currently probe the majority of CCSN candidates in the Milky Way and, once finished, would achieve full galactic sensitivity.

Speaker: Sonia EL HEDRI

14:20 Results from IceCube Follow-up of Nearby Supernova SN2023ixf

Core-collapse supernovae are of particular interest in multi-messenger astronomy due to their potential to accelerate cosmic rays and produce high-energy neutrinos. One such supernova is the recent SN2023ixf located in M101 (the Pinwheel Galaxy). It is the closest (6.4 Mpc) and brightest (B band magnitude 10.8) core-collapse supernova in nearly a decade. This supernova likely had a progenitor surrounded by dense circumstellar material, which during the supernova may have produced neutrinos when ejecta collided with the material. I will present results of a follow up of this supernova using data collected from the IceCube Neutrino Observatory located at the South Pole. We obtain results consistent with background expectations, with time-integrated energy flux (E^2 dN/dE) upper limits of 0.35 GeV/cm^2 for a 32-day time window and 0.44 GeV/cm^2 for a 4-day time window, both at 90% confidence level for an E^-2 power law. These correspond to values of 2.7e48 erg for the 32-day time window and 3.5e48 erg for the 4-day time window at the supernova.

Speaker: Alicia Mand

14:35 IceCat-2: Updated IceCube Event Catalog of Alert Tracks

We present preliminary results for IceCat-2, the second public catalog of IceCat Alert Tracks, which plans to build and improve upon the first release, IceCat-1. The initial catalog included all real-time alerts issued since 2016, as well as events observed by IceCube since the start of full-detector data collection in 2011 that would have triggered an alert if the program had been in place at that time. IceCat-2 plans to expand on this by incorporating all additional alerts since IceCat-1, and reprocessing all events with significantly improved reconstruction algorithms. A key advancement in IceCat-2 will come from an updated reconstruction technique introduced by the IceCube Collaboration in September 2024. This approach substantially enhances the angular resolution of muon track alerts, while also improving statistical coverage. With respect to IceCat-1, the 50%(90%) angular uncertainty on track alerts is expected to be reduced by a factor of approximately 5(4). These refined reconstructions will allow us to revisit possible correlations between past alerts and sources in gamma-ray and X-ray catalogs. The enhanced precision may uncover new astrophysical associations with known astrophysical sources, offering deeper insight into potential cosmic ray accelerators.

Speaker: Angela Zegarelli (Ruhr Universität Bochum (RUB))

14:50 → 15:20 Coffee

15:20 → 16:50 CRD: experimental results: antimatter/transport in the heliosphere, solar modulation

15:20 Antiproton Flux and Properties of Elementary Particle Fluxes in Cosmic Rays Measured with the Alpha Magnetic Spectrometer on the ISS

Precision measurements by AMS reveal unique properties of cosmic charged elementary particles. In the absolute rigidity range ~60 to ~500 GV, the antiproton flux and proton flux have nearly identical rigidity dependence. This behavior indicates an excess of high energy antiprotons compared with secondary antiprotons produced from the collision of cosmic rays. More importantly, from ~60 to ~500 GV the antiproton flux and positron flux show identical rigidity dependence. The positron-to-antiproton flux ratio is independent of energy and its value is determined to be a factor of 1.98 ± 0.03 ± 0.05. This unexpected observation indicates a common origin of high energy antiprotons and positrons in the cosmos. Below 60 GV the antiproton spectrum can not be explained by cosmic rays collisions and above 60 GV the antiproton spectrum can not be explained by latest theoretical models.

Speaker: Hannah Taylor Anderson (Massachusetts Inst. of Technology (US))

15:35 The BESS-Polar II lower-energy antiproton flux using the upper-middle TOF trigger mode

To observe cosmic-origin antiparticles, it is crucial to mitigate the astrophysical background. One approach involved searching for background-free antideuterons/antihelium; however, no viable candidates were identified. Consequently, we extended our antiproton observations to the lower-energy region below 0.2 GeV, where the contribution from secondary particles is minimized, and explored the potential signatures of dark matter in the 4.7×10⁹ cosmic ray events recorded by BESS-Polar II during the solar activity minimum in 2007. We modified the trigger conditions to utilize the middle time-of-flight (TOF), effectively reducing the amount of passing material by half. Additionally, we developed a multi-track analysis method to identify annihilated antiprotons, which are expected to produce backward tracks. We will report the details of the analysis and the lower-energy antiproton flux measured by BESS-Polar II.

Speaker: Kenichi Sakai

15:50 Temporal Structures in Electron and Positron Spectra and Charge Sign Effects in Galactic Cosmic Rays

We present the precision measurements of daily cosmic electron fluxes in the rigidity range from 1.00 to 41.9 GV with 13.5 years data collected with the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station from May 2011 to November 2024. The electron fluxes exhibit variations on multiple time scales. Recurrent electron flux variations with periods of 27 days, 13.5 days, and 9 days are observed. We found that the electron fluxes show distinctly different time variations from the proton fluxes. Remarkably, complex hysteresis between the electron flux and the proton flux is observed. Furthermore, significant structures in the electron-proton hysteresis are observed corresponding to sharp structures in both fluxes.
The positron fluxes show distinctly different time variations from the electron fluxes at short and long time scales. A hysteresis between the electron flux and the positron flux is observed. Unexpectedly, on the long-term time scale positron fluxes are modulated more than proton fluxes.

Speaker: Tong Su (Shandong Institute of Advanced Technology (CN))

16:05 Antiprotons and Elementary Particles over a Solar Cycle: Results from the Alpha Magnetic Spectrometer

We present results over an 11-year Solar cycle of cosmic antiprotons in the rigidity range from 1.00 to 41.9 GV. The antiproton fluxes exhibit distinct properties. Compared with other cosmic elementary particle fluxes (proton, electron, and positron), the magnitude of the antiproton flux temporal variation is significantly smaller. A hysteresis between the antiproton fluxes and the proton fluxes is observed, whereas the antiproton and electron fluxes show a linear correlation. With a model-independent analysis, we found a universal relation between the shape of the rigidity spectrum and the magnitude of flux temporal variation over an 11-year Solar cycle for both positively and negatively charged particles. The simultaneous results on antiproton, proton, electron and positron provide unique information for understanding particle transport in the Solar System as a function of mass, charge, and spectral shape.

Speaker: Dr Zhi-Cheng Tang (Institute of High Energy Physics, Chinese Academy of Sciences)

16:20 Precision Measurement of the Monthly Light Ion Fluxes in Cosmic Rays with the Alpha Magnetic Spectrometer on the International Space Station

Cosmic rays inside the heliosphere interact with the solar wind and with the interplanetary magnetic field, resulting in a temporal variation of the cosmic ray intensity near Earth for rigidities up to a few tens of GV. Previous AMS results on proton and helium spectra showed that the two fluxes behave differently in time. In this contribution, the precision results of the light ions up to Oxygen for the 12.5 years of data collected by the AMS will be presented including detailed temporal variations of the fluxes.

Speaker: Jian Tian (INFN e Universita Roma Tor Vergata (IT))

16:35 Time-Dependent Measurements of Absolute Spectra for Elements up to Fe by SuperTIGER as a Probe of Solar Modulation, Atmospheric and Geomagnetic Rigidity Effects

SuperTIGER (Super Trans-Iron Galactic Element Recorder) is a large-area, balloon-borne cosmic-ray experiment designed to measure the galactic cosmic-ray abundances of elements from Z=10 to Z>30 at energies from $\sim$0.8 to $\sim$10 GeV/nuc. Measurements of ultra-heavy elements (Z>30) requires precise calibration from Z<30 elements, and we will report energy spectra at this meeting. SuperTIGER flew over Antarctica for 55 days in 2012-2013, and it flew a second flight of 32 days in 2019-2020. The long, separate flights allow the measured spectra to be used to examine solar modulation, atmospheric, and geomagnetic effects. The first flight occurred when the solar modulation parameter was $\sim$520–650 MV, between solar minimum and solar maximum based on ACE/CRIS measurements, and during the second flight, it was $\sim$200-250 MV, near solar minimum. We will show the effects of solar modulation at the lowest energies measured by SuperTIGER. Additionally, during the first flight, the instrument circumnavigated Antarctica, drifting between 74.9 to 86.6 degrees South latitude, while during the second flight, the instrument drifted between 69.5 to 77.9 degrees South latitude. The northern reach of the second flight raises the possibility of probing vertical cutoff rigidities with low energy intensities in the flight data, and we will compare results of both flights with vertical cutoff rigidity maps calculated for both flights. Finally, the atmospheric overburden (a measure of altitude) during the first SuperTIGER flight varied between 3.64 and 6.65 g/cm$^2$, and it varied between 3.76 and 8.34 g/cm$^2$ during the second flight. We will compare elemental intensity variations, measured at the top of the instrument, vs. atmospheric overburden, and we will compare these results with atmospheric survival fractions vs. element and energy as calculated by Geant4 simulations.

Speaker: Allan Labrador

15:20 → 16:50 CRI: phenomenology

15:20 Ultra-High-Energy Cosmic Rays from Tidal Disruption Events: Composition, Spectrum, and Challenges

We investigate Tidal Disruption Events (TDEs) as potential sources of Ultra-High-Energy Cosmic Rays (UHECRs), motivated by recent associations between high-energy neutrinos and individual TDEs. A key challenge is bridging the gap between these few identified neutrino sources and a broader population of UHECR accelerators. Additionally, we assess the nuclear composition required to match UHECR data, considering stellar progenitors disrupted in TDEs. Our findings suggest that TDEs could explain the observed UHECR spectrum and composition if the acceleration mechanism favors heavier nuclei. The associated diffuse neutrino flux is expected to peak around 50 PeV, supporting a potential connection between UHECR sources and a recent high-energy neutrino detection by KM3NeT.

Speaker: Walter Winter

15:35 Multi-messenger constraints on transient accelerators of ultra-high energy cosmic rays

The origin of ultra-high-energy cosmic rays (UHECRs) remains an open questions in astrophysics. We explore two primary scenarios for the distribution of UHECR sources, assuming that their production rate follows either the cosmic star-formation-rate or stellar-mass density. By jointly fitting the UHECR energy spectrum and mass composition measured by the Pierre Auger Observatory above the ankle ($10^{18.7}$ eV), we derive constraints on the acceleration mechanisms, source energetics, and elemental abundances at escape. Using these constraints, we generate sky maps above 40 EeV based on a catalog of over 400,000 galaxies out to 350 Mpc, providing a near-infrared flux-limited sample that maps the two stellar-activity tracers across the full sky.
A crucial factor in understanding UHECR propagation is the influence of large-scale cosmic structures, particularly galaxy clusters—the largest gravitationally bound systems in the Universe, which are filled with magnetized diffuse plasma. Intermittent sources hosted in galaxies within such structures, coupled with cosmic magnetic fields, shape the observed UHECR arrival directions and provide insights into the burst rate of the sources. We show that these environments can significantly impact UHECR transport, making them particularly opaque to heavy nuclei. Additionally, we compute the expected secondary neutrino and photon fluxes from UHECR interactions in these environments and compare them with current experimental limits, constraining the maximum energy that particles can achieve. Finally, we assess the compatibility of these constraints with astrophysical candidates, identifying long gamma-ray bursts as the most promising sources.

Speaker: Antonio Condorelli

15:50 Ultra-high-energy cosmic rays from ultra-fast outflows of active galactic nuclei

We investigate ultra-fast outflows (UFOs) in active galactic nuclei (AGN) as potential sources of ultra-high-energy cosmic rays (UHECRs), focusing on cosmic-ray nuclei, an aspect not explored previously. These large-scale, mildly-relativistic outflows are a common feature of AGN. We study the cosmic-ray spectrum and maximum energy attainable in these environments with 3D CRPropa simulations and apply our method to 86 observed UFOs. Nuclei can be accelerated up to $100\,$EeV at the wind-termination shock in some UFOs, but their escaping flux is strongly attenuated due to photonuclear interactions with intense AGN photon fields. In the most extreme $\sim10\%$ of UFOs in our sample, nuclei can escape with energy exceeding $\sim500\,$PeV. In contrast, protons typically escape UFOs with only mild attenuation, with half of the observed UFOs reaching ultra-high energies. We show that UFOs can explain the observed UHECR flux in the transition region below the ankle and potentially contribute to the flux of cosmic-ray nuclei up to the highest energies. An important multimessenger signature is provided by the PeV astrophysical neutrinos expected from interactions of the accelerated cosmic rays in the UFOs.

Speaker: Domenik Ehlert (Norwegian University of Science and Technology)

16:05 Spectrum and Composition of Ultrahigh Energy Cosmic Rays produced in the magnetized turbulent outflow of Binary Neutron Star mergers, and the time delay of associated EHE neutrinos

Circumstantial evidence points to binary neutron star (BNS) mergers as the principal source of ultrahigh energy cosmic rays (UCRs), as will be briefly reviewed. This motivates trying to predict consequences of the BNS merger scenario for the UCR spectrum and composition, and also multi-messenger implications in particular gravitational wave-EHE neutrino coincidences. In this talk I will
1) Report briefly on the recent PIC simulation of Comisso et al (2024) showing that acceleration in magnetized turbulence produces the spectrum E^{-2.1} sech[(E/E_cut)^2]. This gives a good fit to UCR spectrum and composition data — much better than the exponential cutoff associated with diffusive shock acceleration (Protheroe&Stanev 1999).
2) Calculate the UCR cutoff rigidity, assuming acceleration occurs in the turbulent outflow (not the jets), initializing the outflow magnetic field with the ultrahigh resolution neutrino-GRMHD simulation of Kiuchi et al 2024 and using a simple treatment of synchrotron emission. The analysis predicts a rigidity (E/Ze) cutoff of 5.5 - 7 EV, consistent with the value 6.8 EV from fitting the Auger spectrum and composition data with the spectrum of magnetized turbulence.
3) Calculate the time delay of an EHE neutrino relative to the associated gravitational wave. The analysis 2) shows that UCRs are predominantly accelerated at a radius of about 10^{14} cm, implying a time-delay of order one day for neutrinos relative to the arrival time of the gravitational wave produced by the merger. With next-generation gravitaional wave and EHE neutrino detectors, such coincidences may be detectable and would provide decisive evidence of this scenario. Coincidences with short GRBs are also a possibility.
4) Outline the calculation required for predicting the composition of UCRs in the BNS merger scenario, and discuss the prediction that UCRs with energies >~ 150 EeV originated as r-process elements such as Tellurium and Xenon.
5) Discuss the principle challenges to this scenario and the most pressing studies which need to be done.

Speaker: Glennys R. Farrar (New York University)

16:20 Ultraheavy Ultrahigh-Energy Cosmic Rays

We investigate the propagation of ultraheavy (UH) nuclei as ultrahigh-energy cosmic rays (UHECRs). We show that their energy loss lengths at $\lesssim300$~EeV are significantly longer than those of protons and intermediate-mass nuclei, and that the highest-energy cosmic rays with energies beyond $\sim100$~EeV, including the Amaterasu particle, may originate from such UH-UHECRs. We derive constraints on the contribution of UH-UHECR sources, and find that they are consistent with energy generation rate densities of UHECRs from collapsars and neutron star mergers.

Speaker: Bing Theodore Zhang (Institute of high energy physics, CAS)

16:35 Simulating the propagation of cosmic rays heavier than iron in SimProp

Ultra-high-energy cosmic rays (UHECRs) have long been assumed to entirely consist of iron and/or lighter atomic nuclei, and this assumption has been hard-coded in a great deal of software for UHECR simulations and data analysis. However, in the last few years several authors have started questioning this assumption and entertaining the possibility that UHECRs might at least partly consist of nuclei of elements heavier than iron, especially at the highest energies. Thoroughly testing this hypothesis will require upgrading software so that it can handle such nuclei. In this contribution I will describe the minimal modifications required for the last publicly released version of SimProp, a code for Monte Carlo simulations of the intergalactic propagation of UHECRs, to be able to treat heavier nuclei, and discuss the applicability of approximations first introduced for lighter nuclei.

Speaker: Armando di Matteo (INFN Torino)

15:20 → 16:35 DM: astrophysics

15:20 Probing late-time annihilations of oscillating asymmetric dark matter via rotation curves of galaxies

In this work, we investigate the Oscillating Asymmetric Dark Matter (OADM) model as a potential solution to the core-cusp problem, a well-known discrepancy between the predictions of the ΛCDM (Lambda Cold Dark Matter) cosmological model and the observed dark matter density profiles in dwarf spheroidal galaxies. While ΛCDM simulations typically predict a steep, cusp-like increase in dark matter density toward the centers of galaxies, observations often reveal flatter, core-like profiles. To address this issue, we analyze a mechanism in which dark matter annihilation is reactivated during the structure formation epoch, facilitated by a small Majorana mass term that breaks the conservation of dark matter particle number. This leads to oscillations between dark matter particles and their antiparticles, altering the density profiles of dark matter halos.
We analyze the impact of this annihilation mechanism on galaxy rotation curves using data from the SPARC (Spitzer Photometry and Accurate Rotation Curves) and LITTLE THINGS (Local Irregulars That Trace Luminosity Extremes, The HI Nearby Galaxy Survey) catalogs. By identifying the specific characteristics of the OADM model that best fit the observed data, we demonstrate that the model successfully converts cusp-type halos—predicted by ΛCDM—into core-type halos, consistent with the observed profiles in our data sample. Our results suggest that the OADM model provides a compelling explanation for the core-cusp problem, offering a dynamic mechanism to reconcile theoretical predictions with observational data. This work highlights the potential of the OADM framework to advance our understanding of dark matter dynamics and its role in shaping galactic structures.

Speaker: Júlia Gouvêa Mamprim (Universidade de São Paulo)

15:35 A detailed characterisation of low-mass dark matter subhalo tidal tracks via numerical simulations

A number of studies assert that dark matter (DM) subhaloes without a baryonic counterpart and with an inner cusp always survive no matter the strength of the tidal force they undergo.
In this work, we perform a suite of numerical simulations specifically designed to analyse the evolution of the circular velocity peaks ($V_\mathrm{max}$, and its radial value $r_\mathrm{max}$) of low-mass DM subhaloes due to tidal stripping. To perform this task, we have employed the improved version of the DASH library, introduced in our previous work Aguirre-Santaella et al. (2023) to study subhalo survival.
More specifically, we follow the tidal evolution of a single DM subhalo orbiting a Milky Way (MW)-size halo, the latter with a baryonic disc and a bulge replicating the actual mass distribution of the MW. We simulate subhaloes with unprecedented accuracy, varying their initial mass, concentration, orbital parameters and inner slope (NFW and prompt cusps are considered). We also consider the effect of the time-evolving gravitational potential of the MW itself.
Here, we also broaden our vision with respect to previous literature not just characterizing tidal tracks at the apocentres, but exploring the pericentres as well. Several important discrepancies arise, especially with respect to works that do not account for baryonic material inside the host.
For our fiducial setting, we find $V_\mathrm{max}$ to change approximately the same after each orbital period, whilst $r_\mathrm{max}$ decreases less drastically for later orbits. This implies a larger increase in velocity concentrations for the first orbit compared to subsequent ones.
In general, $r_\mathrm{max}$ shrinks more than $V_\mathrm{max}$, leading to a continuous rise of subhalo concentration with time. The velocity concentration at present is found to be up to two orders of magnitude higher than the one at infall.
These findings significantly enhance our understanding of the dynamics and properties of low-mass DM subhaloes, providing valuable insights for future research, simulations and observations, as well as for indirect searches of DM.

Speaker: ALEJANDRA AGUIRRE-SANTAELLA (Institute for Computational Cosmology, Durham University)

15:50 The CMZ anomalous Ionization rate explained by MeV DM

Recent observations of a variety of ionization tracers have revealed an unexpectedly high ionization rate in the Central Molecular Zone (CMZ), that cannot be explained by ionization of cosmic rays. The current observations point to a source of particles that is very concentrated around the Galactic Center and should emit low energy ionizing particles (to avoid propagating too far away from the CMZ). In this talk, I'll show that the anomalous ionization rate observed in the CMZ can be attributed to MeV dark matter annihilation for galactic dark matter profiles with slopes γ > 1 and that the low annihilation cross-sections required avoid (by a few orders of magnitude) the current cosmological constraints and imply no detectable inverse Compton, bremsstrahlung or synchrotron emissions in radio, X and gamma rays.
Moreover, I'll discuss the possible common origin of this anomaly with the puzzling 511 keV line emission in the Galactic Center

Speaker: Pedro De la Torre Luque (Institute of theoretical physics (IFT-UAM))

16:05 Astrophysical jets to constrain the dark matter nature

Astrophysical jets of powerful active galactic nuclei (AGN) have been recently put forward as promising probes of dark matter (DM) at the sub-GeV-mass scale. AGN launch relativistic jets that accelerate cosmic rays (CRs) to energies beyond the PeV scale. These CRs may interact with their surroundings, producing multiwavelength (MW) emission from radio to TeV γ rays. If DM consists of light particles, CR-DM interactions—whether elastic or inelastic—could lead to additional secondary particles, modifying the expected MW emission. Previous studies have neglected uncertainties in astrophysical jet dynamics when constraining CR-DM interaction cross-section for boosted DM. In this work, we develop a novel statistical framework to assess the impact of jet kinematics on DM constraints. Using a multizone jet model for Markarian 421, a well-studied AGN, we investigate the DM-induced radiative signatures. Our results offer new insights into the role of relativistic jets in
unveiling the nature of DM.

Speaker: Dimitrios Kantzas

16:20 Impact of baryons on the population of galactic subhalos and implications for dark matter searches

In standard $\Lambda$CDM cosmology, dark matter (DM) halos are teeming with numerous substructure, or subhalos, as a natural consequence of the way structure formation works in $\Lambda$CDM. If massive enough, both halos and subhalos host visible galaxies, while lighter ones would host no stars or gas at all and would remain dark (dark satellites). In this work, we have used Auriga - a set of state-of-the-art cosmological hydrodynamical simulations of Milky Way-size systems - to study the impact of baryons on the Galactic subhalo population. A DM-only simulation counterpart of Auriga, also available, allows us to compare results with and without baryons. Since the resolution of these simulations is limited, we applied an algorithm to repopulate the original simulations with low-mass subhalos well below the resolution limit. The survival of low-mass subhalos to tidal forces is unclear and under fierce debate nowadays, so in our study we stay agnostic to it and consider two different degrees of subhalo resilience to tidal stripping ('fragile' and 'resilient' subhalos). We find baryons to alter the Galactic substructure significantly, by decreasing its overall abundance by a factor $\sim2.4$ (fragile) and $\sim1.9$ (resilient) and the concentration of individual subhalos by $\sim1.5$ with respect to their DM-only counterparts. This has important consequences for e.g. indirect searches of DM, in particular those focused on the use of unidentified gamma-ray sources to set constraints on the DM particle properties. We find the DM annihilation cross-section constraints - based on DM-only simulations and the same setup of subhalo resilience - to worsen by a factor $\sim3.8$ in the most realistic case of including baryons. Yet, a stronger resilience of subhalos to tidal stripping improves these DM limits by a factor $\sim4.6$ and $\sim11.4$ compared to the DM-only and hydrodynamical 'fragile' cases, respectively. Our results show the importance of including baryons to properly characterize the Galactic subhalo population, and to propose the most optimal subhalo search strategies, not only via its potential annihilation products but also their gravitational signatures (e.g. stellar streams, lensing).

Speaker: Sara Porras Bedmar (Universitaet Hamburg)

15:20 → 16:36 GA: galaxies, gravitational lens & Lorentz invariance

15:20 The diffuse extragalactic gamma-ray background radiation: star-forming galaxies are not the dominant component

Star-forming galaxies (SFGs) are considered to be an important component of the diffuse extragalactic gamma-ray background (EGB) radiation observed in 0.1 -- 820 GeV, but their quantitative contribution has not yet been precisely determined. In this study, we aim to provide the currently most reliable estimate of the contribution of SFGs based on careful calibration with $\gamma$-ray luminosities of nearby galaxies and physical quantities (star formation rate, stellar mass, and size) of galaxies observed by high-redshift galaxy surveys. Our calculations are based on the latest database of particle collision cross-sections and energy spectra of secondary particles, and take into account not only hadronic but also leptonic processes with various radiation fields in a galaxy. We find that SFGs are not the dominant component of the unresolved EGB measured by Fermi; the largest contribution is around 50% -- 60% in the 1 -- 10 GeV region, and the contribution falls rapidly in lower and higher energy ranges. This result appears to contradict a previous study, which claimed that SFGs are the dominant component of the unresolved EGB, and the origin of the discrepancy is examined. In calculations of cosmic-ray production, propagation, and interaction in a galaxy, we try models developed by two independent groups and find that they have little impact on EGB.

Speaker: Junling CHEN (the University of Tokyo)

15:35 No evidence for gamma-ray emission from the Sagittarius dwarf spheroidal galaxy

More than a decade ago, the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope unveiled the existence of two gigantic gamma-ray lobes known as the Fermi bubbles. While their origin is still unknown, various studies identified intricate spectral and morphological structures within the bubbles. One peculiar region, the cocoon, has recently been associated with gamma-ray emissions from the Sagittarius dwarf spheroidal (Sgr) galaxy.
We assess the validity of this claim through adaptive-template fitting and pixel-count statistical methods. Our approach introduces a substantial advancement in data interpretation by enabling a data-driven optimisation of astrophysical background models, thereby reducing the impact of background mis-modelling.
We do not find evidence for gamma-ray emission from the Sgr region at the level obtained in previous work. We demonstrate that there is no pronounced difference between the source population located within the cocoon region and a reference region at similar latitudes. We examine the hypothesis that a millisecond pulsar population in Sgr causes the putative signal via dedicated simulations finding that it is unlikely that we may have detected their presence in Sgr.

Speaker: Christopher Eckner (University of Nova Gorica, Center for Astrophysics and Cosmology)

15:50 Probing Circumgalactic Cosmic Rays around the Milky Way with GeV-PeV Gamma Rays and Neutrinos

Cosmic ray (CR) hadrons with GeV-PeV energies are expected to reside in the circumgalactic medium (CGM) around the Milky Way (MW), having escaped from the Galactic disk, or injected in situ by satellite galaxies, large scale shocks due to Galactic winds, etc. In some cases, circumgalactic CRs (CGCRs) may play important thermal and dynamical roles in the evolution of galaxies, but observational evidence for them is very scarce to date. To probe CGCRs through pp-induced gamma rays, we discuss the unique advantages of the PeV band compared to the GeV-TeV bands, which include 1) absence of a bright extragalactic gamma-ray background due to γγ absorption with the CMB, and 2. constraints on distance of origin from the photon energy via the energy-dependence of the γγ mean free path that covers interesting CGM scales. Recent observations of the MW CGM suggest that the cool, highly structured gas traced by intermediate-velocity clouds (IVCs) and high-velocity clouds (HVCs) is comparable to the hot gas in total mass, implying that gamma-ray and neutrino emission from the MW CGM can be significantly anisotropic. Using data from Tibet ASγ, we search for signals associated with IVCs and HVCs, and find no clear evidence so far. We discuss the implications for the origin and propagation of CRs around the MW, expectations for LHAASO, and the relation to high-energy neutrinos observed by IceCube. The prospects for future Southern facilities such as ALPACA and SWGO are also discussed.

Speaker: Susumu Inoue

16:05 Measurement of the time delay in the gravitationally lensed system PKS 1830-211

The gravitationally lensed blazar PKS 1830-211 underwent a historically bright and unusually long-duration gamma-ray flaring episode in 2019/2021 with daily fluxes exceeding > $10^{-6}$ ph/cm$^2$/s for ~400 days, and daily peak fluxes (> $10^{-5}$ ph/cm$^2$/s) exceeding all prior flares observed by the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope in the first 15 years of operation. We analyzed six bright flaring episodes (~hundreds of days long) independently using an auto-correlation function analysis, improved by a new methodology for detrending of the gamma-ray light curve, i.e. the removal of the underlying low-frequency trend due to the red noise stochastic components. We identify a significant delay in the gamma-ray data of the order of 20 days. The value is consistent over the different observational epochs, and is attributable to the gravitational lensing effect. The results and uncertainties presented here account for stochastic variability of the blazar for the first time and, in contrast to prior works that considered the earliest fainter flaring intervals and reported disparate time delay values in gamma rays, we here consider improvements in the reliability of the LAT lightcurves, and benefits from improvements enabled by the present LAT calibrations. In this contribution, we present these new findings, and discuss how the possible discrepancy between the time delay measured at gamma-rays (20 days) and the one derived from radio observations (~25 days) may be reconciled, e.g. as a probe of different emission regions responsible for the gamma rays and radio emission, and/or microlensing effects.

Speaker: Margherita De Toma (SISSA)

16:20 Searching for Lorentz invariance violation with artificial neural networks

Lorentz invariance violation (LIV) can have multiple consequences on very-high energy gamma rays’ emission, propagation, and detection, such as energy-dependent photon group velocity, photon instability, vacuum birefringence, and modified electromagnetic interaction. Depending on the underlying theoretical model, several of these effects can coexist. Nevertheless, in experimental tests of LIV, each effect is tested separately and independently. For the first time, we are performing a search for traces of several coexisting effects in a single analysis. We present our analysis method based on artificial neural networks and put our very first results in the context of experimental searches for LIV.

Speaker: Tomislav Terzić

15:20 → 16:35 GA: pulsars and halos

15:20 Kinetic simulations of electron-positron streaming instability in the context of gamma-ray halos and X-ray filaments around pulsars

The presence of slow diffusion regions as a possible explanation for extended TeV emission around pulsars such as Geminga, Monogem, and PSR J0622+3749, as well as for the X-ray filaments surrounding bow shock pulsar wind nebulae like the Guitar Nebula, PSR J2030+4415, and the Lighthouse Nebula, challenges the conventional understanding of the cosmic ray diffusion coefficient in the interstellar medium.
One proposed mechanism for the suppression of the diffusion process, which is essential for shaping these halos, is the self-generated turbulence driven by streaming electron-positron pairs escaping the pulsar wind nebula. In this work, we study the magnetic field amplification driven by plasma instabilities induced by pair beams using fully kinetic 2D particle-in-cell simulations, focusing on a scenario where electrons and positrons stream with equal densities in an electron-proton background plasma, resulting in no net beam current. Our results show that the amplification of the background magnetic field strongly depends on the ratio between the beam’s energy density and the total energy density of the background plasma, including both magnetic and thermal components.
A key finding is that when the magnetic field is amplified, local charge separation naturally emerges, leading to localized overdensities of electrons relative to positrons or vice versa. These results suggest that this asymmetry could eventually give rise to a non-resonant streaming instability, significantly influencing the magnetic field structure. The identified mechanism provides a natural way to induce local asymmetry in the initial beam, leading to distinct electron and positron dynamics. These effects could have important implications for turbulence generation near pulsar wind nebulae, as well as for the formation of TeV halos and X-ray filaments around bow shock pulsar wind nebulae.

Speaker: Luca Orusa (Princeton University, Columbia University)

15:35 Interstellar Magnetic Field Effects on the Asymmetric Structure of Pulsar Halos

There has been ongoing debate about the potential unconfirmed asymmetric structure of the diffuse $\gamma$-ray emission of the Geminga halo. In this work, we adhere to first principles, injecting and propagating individual cosmic ray (CR) electrons in 3D realizations of turbulent magnetic fields characterized by Kolmogorov turbulence and Bohm diffusion. The particle motion is governed by the Lorentz force, and their energy losses are accounted for through synchrotron and inverse Compton scattering. Furthermore, we consider potential regular magnetic field and the inclination angle between the line of sight (LOS) and the magnetic field lines (MFLs) direction, calculating the resulting gamma-ray emission, comparing it with the HAWC surface brightness measurements. We confirmed that the coherence length $L_{\rm c}$ could be constrained around 1 pc as previous work suggested, the $\chi^2$/d.o.f. fitting findings using the HAWC data suggest that the presence of a regular magnetic field has a marginal improvement over a purely turbulent magnetic field. Since Bohm diffusion corresponds to the cosmic-ray-driven instability case, which represents more tangled MFLs and isotropic CRs densities around the injection location, performs worse than Kolmogorov turbulence. This results suggest the possibility of potential filamentary structure inside the Geminga halo, while limited by the resolution of very-high-energy (VHE) detectors, the inner asymmetry structure may be invisible. In extreme situation, such as a large $L_{\rm c}$ is superimposed with a strong regular magnetic field, when the LOS is coincidently parallel to the direction of the MFL, the resulting pulsar halo morphology is overall isotropic. However, our results suggest that even in this scenario, the intrinsic filamentary structure would not be disrupted.

Speaker: Yuan LI

15:50 The environment of TeV halo progenitors

Since the discovery of TeV halos around the Geminga and B0656+14 pulsars by the HAWC experiment in 2017, and around J0622+3749 by LHAASO in 2021, several theoretical efforts have been dedicated to understanding this source class. Surprisingly, the gamma-ray emission hints at a strong confinement of high-energy electron-positron pairs around the pulsar, which challenges our current understanding of the transport of cosmic particles in Galactic environments. Making sense of pulsar halos requires first and foremost knowing the nature of the medium that pairs are released into. In this work, we aim at providing such an information from a population perspective.

We compute semi-analytically the evolution of pulsars and supernova remnants in both star clusters and wind-blown bubbles environments and generate a full Galactic population from a Monte-Carlo sampling of the main parameters of the problem (kick velocities, cluster membership, etc). We eventually produce statistics about the medium where pulsars are to be found at any given age, which can be useful in addressing the question of the origin of TeV halos since some environments can naturally be expected to be more turbulent than others. We specifically examine known nearby pulsars from the ATNF catalog, and give their probability of being inside their parent remnants or superbubbles. We find that most galactic pulsars escape into the interstellar medium at more than $200~\mathrm{kyr}$ instead of the fiducial $\lesssim60~\mathrm{kyr}$ value often quoted in the literature. We discuss the possible implications of these findings on the likelihood that a pulsar develops a TeV halo and on its detectability with current and future gamma-ray detectors, as well as the possible impact on the release of lepton pairs in the Galaxy in connection with the so-called positron excess.

Speaker: Lioni-Moana Bourguinat

16:05 Generating the TeV gamma-ray sky from population synthesis of pulsar environments

Pulsar associations constitute the most numerous class of Galactic TeV sources, with pulsar wind nebulae (PWNe) and pulsar halos playing a crucial role in high-energy astrophysics. We build a population synthesis pipeline based on the COMPAS code to model stellar evolution and pulsar populations. Our framework tracks the evolution of pulsars through various PWN and pulsar halo stages, predicting both gamma-ray emission and nebular size distributions. By normalizing our model against observed northern sky surveys, we assess detectability constraints and provide a predictive outlook for the southern sky. This analysis offers valuable insights into the expected TeV source population and their observational prospects with upcoming facilities.

Speaker: Giovanni Cozzolongo

16:20 H.E.S.S. Observations of TeV pulsars

The recent discovery of multi-TeV pulsed emission from Vela and PSR J1509-5850 represents a major breakthrough in pulsar physics. We present the latest findings from very high-energy (VHE) observations using the H.E.S.S. telescopes and discuss key similarities and differences in the emission properties of these two pulsars in the GeV and multi-TeV ranges, in relation to their main characteristics. We then examine the implications for theoretical models describing high-energy pulsar emission. These results not only refine existing models but also pave the way for future TeV observations and studies of pulsars.

Speaker: Mr Maxime REGEARD (APC - CNRS)

15:20 → 16:50 NU: atmospheric interpretations & MM studies

15:20 Impact of multi-messenger spectral modelling on blazar-neutrino associations

Blazars are promising candidates for astrophysical neutrino sources. Multi-messenger lepto-hadronic models based on proton–photon ($p\gamma$) interactions predict spectra that peak at high energies, whereas statistical searches often assume a power-law shape, emphasising lower energies. We investigate how these spectral assumptions impact neutrino--blazar associations by incorporating physically motivated spectra into our Bayesian point-source framework. Using predictions from Rodrigues et al. (2024), we analyse 10 years of IceCube data and identify five candidate sources. Our results show that $p\gamma$ spectra suppress low-energy associations but may enhance high-energy ones. Strong associations then imply that energetic neutrino events likely have much higher true energies than those inferred under a power-law assumption. This is particularly relevant in light of the recent KM3NeT detection of the highest-energy neutrino, reinforcing the need for theory-driven models to interpret multi-messenger signals.

Speaker: Julian Kuhlmann (Max-Planck-Institute for Physics)

15:35 Correlation between the unabsorbed hard X-rays and neutrinos in radio-loud and radio-quiet AGN

In our recent paper, we demonstrated that the luminosity ratios of neutrinos and unabsorbed hard X-rays from the blazars TXS 0506+056 and GB6 J1542+6129 are consistent with neutrino production in a γ-ray obscured region near a central supermassive black hole. The X-ray flux appears to arise from reprocessed γ-ray emission with a flux comparable to that of the neutrinos. Similar neutrino–hard X-ray flux ratios are found for four Seyfert galaxies-NGC 1068, NGC 4151, CGCG 420-015, and NGC 3079-suggesting a common neutrino production mechanism that may not require a strong jet. In this contribution, we will present our findings and discuss their implications for future research.

Speaker: Emma Kun (Ruhr University Bochum)

15:50 Evidence of Neutrino Emission from X-ray Bright Seyfert Galaxies with IceCube

The IceCube Neutrino Observatory has detected evidence for TeV neutrinos from NGC 1068, a nearby Seyfert II galaxy. This discovery suggests that active galactic nuclei (AGN) may play a significant role as sources of high-energy astrophysical neutrinos. Interestingly, the absence of the expected TeV gamma-ray flux indicates that these gamma-rays could be effectively obscured at their production site, with the hot coronal environment near the Seyfert galaxy’s core being a plausible location for this attenuation. Theoretical models suggest that the properties of the corona—and thus the production of neutrinos—can be inferred from the galaxy’s intrinsic X-ray luminosity. In this presentation, we report our search for neutrino emission from a sample of X-ray bright Seyfert galaxies selected from the BASS survey. We have employed a disc-corona model to predict the neutrino flux, improving the sensitivity of our search, and compared this model to the more traditional power-law flux assumption. Our stacking analysis shows a 3σ signal of neutrino emission from the collective sources in the catalog.

Speaker: Shiqi Yu

16:05 Constraining the contribution of Seyfert galaxies to the astrophysical neutrino flux using NGC 1068 as a benchmark

IceCube recently reported evidence for TeV neutrino emission from several nearby Seyfert galaxies, with the highest significance found for NGC 1068. The absence of TeV gamma rays suggests neutrino production in the AGN corona, which is opaque to high-energy photons. Assuming stochastic proton acceleration, we model the neutrino emission of a Seyfert galaxy as a function of its intrinsic X-ray luminosity, considering both photohadronic and hadronuclear interactions. We fit the resulting neutrino spectrum for NGC 1068 to public IceCube data and find that our model provides a good fit to the data while remaining consistent with Fermi-LAT gamma-ray constraints. Using this as a benchmark, we apply our model to a sample of nearby Seyfert galaxies and a simulated source population based on the X-ray luminosity function of AGNs. We go beyond previous work by modelling the details of individual sources, considering both nearby X-ray observations and the broader population in a consistent way. We find that Seyfert galaxies could contribute significantly to the diffuse neutrino flux in the 1-10 TeV range. However, if all Seyferts were as efficient as NGC 1068, their combined flux would exceed current upper limits at TeV energies by more than $3\sigma$, suggesting that NGC 1068 is an unusually powerful neutrino source.

Speaker: Lena Saurenhaus (Max Planck Institute for Physics)

16:20 Multimessenger-Informed Characterization of High-Energy Neutrino Emission from Bright Seyfert Galaxies

Observation of high-energy neutrinos from the direction of the nearby active galaxy, NGC 1068, was a major step in identifying the origin of high-energy neutrinos. This observation revealed that high-energy neutrinos originated at the heart of active galaxies, which are opaque to very-high-energy gamma-ray emission. This realization is further reinforced by the multimessenger picture for the observed all-sky neutrino flux in IceCube as well as the recently identified excess of neutrinos in the direction of NGC 4151, another nearby AGN. Modeling neutrino emission from the core of AGN relies on the multi-wavelength observations of the inner parts of the active galaxy and is challenging due to the uncertainties associated with the absorption of emission in these dense environments. Here, we employ the measured neutrino spectra together with the sub-GeV gamma-ray emission measured by the Fermi satellite to break the degeneracy and narrow down the parameter space of neutrino emission from the coronae of AGN. Our result will help estimate the prospects for identifyin additional sources and guide future targeted analyses.

Speaker: Ali Kheirandish (University of Nevada, Las Vegas)

16:35 Neutrino and Cosmic Ray Emission of Coronae of Supermassive black holes

We present a generalized neutrino luminosity function for protons accelerated in the coronae of supermassive black holes (SMBH) in Seyfert-like galaxies, using NGC 1068 as a benchmark. The neutrino luminosity mainly depends on the coronal x-ray luminosity and SMBH mass. Our results suggest that the cosmologically-integrated neutrino luminosity could match the extragalactic diffuse IceCube signal below PeV levels. We conclude that the energetically-significant proton luminosity associated with such neutrinos is sufficientt to drive a mildly relativisitic coronal outflow, and possibly contribute to feedback processes.

Speaker: Dr Rostom Mbarek

15:20 → 16:50 NU: experimental & next generation

15:20 The Candidate Blazar Counterparts of the Ultra-High-Energy Event KM3-230213A

The detection by the KM3NeT experiment of the ultra-high-energy event KM3-230213A marks a milestone in neutrino astrophysics. With an energy estimated at ~ 220 PeV, it is the most energetic cosmic neutrino observed to date, opening the question of its astrophysical origin. Blazars, among the most powerful cosmic accelerators, have been proposed as promising sources of both astrophysical neutrinos and ultra-high-energy cosmic rays. In this contribution, seventeen candidate blazars are identified in the 3° radius error region of KM3-230213A through their multiwavelength signatures. Using archival data and dedicated observations, their properties are characterised throughout the whole electromagnetic spectrum, from radio to gamma rays. Three sources exhibit flaring behaviour in one of the examined bands, in coincidence with the neutrino arrival time. While none of these can be unequivocally associated with the neutrino, the implications of a possible blazar origin of the KM3NeT event are discussed.

Speaker: Dr Massimiliano Lincetto (U. Würzburg)

15:35 Search for a cosmic point-like neutrino source from the direction of the ultra-high-energy event KM3-230213A

On February 13, 2023, the KM3NeT/ARCA neutrino telescope detected an ultra-high-energy neutrino event, KM3-230213A, with an estimated energy of approximately 220 PeV — the most energetic neutrino ever observed. This unprecedented event marks a significant milestone in the field of astroparticle physics, offering new insights into the potential sources of these extreme astrophysical phenomena.
In this work, we present a follow-up analysis aimed at identifying a potential cosmic point-like neutrino source associated with KM3-230213A. We perform a dedicated search for additional neutrino events in the direction of KM3-230213A using data from KM3NeT/ARCA, KM3NeT/ORCA, ANTARES and IceCube. In order to assess the potential spatial clustering of neutrino events around KM3-230213A, we employ either an ON/OFF technique or a maximum-likelihood method.
This contribution presents the methodology, the datasets used, the event selection criteria, and the statistical methods applied. We discuss the results in the context of multi-messenger astrophysics, highlighting their implications for the origin of the ultra-high-energy neutrino KM3-230213A.

Speaker: Martina Marconi (INFN Genova - Università di Genova)

15:50 Model-agnostic interpretation of the first KM3NeT Ultra-High-Energy event within the Global Neutrino Landscape

On February 13th, 2023, the KM3NeT/ARCA telescope detected a neutrino candidate with an estimated energy in the hundreds of PeVs. We review the observation of this ultra-high-energy neutrino in light of observations above tens of PeV from the IceCube and Pierre Auger observatories. Furthermore, we discuss how the ultra-high-energy data were fit together with the IceCube measurements at lower energies, either with a single power law or with a broken power law, allowing for the presence of a new component in the spectrum. Finally, we present the prospects that may lead to resolving this apparent discrepancy and better characterise the neutrino landscape at ultra-high energies.

Speaker: Jonathan Mauro (UCLouvain)

16:05 Ultra-high-energy neutrino detection with radio antennas in the ground-based observatory

The detection of Ultra-High-Energy (UHE) neutrinos offers a unique opportunity to unravel the mysteries surrounding the astrophysical origins of the universe’s most energetic cosmic rays. Radio detection promises significant advantages for detecting highly inclined air showers induced by UHE neutrinos, including a larger exposure range compared to particle detectors, which is due to minimal atmospheric attenuation of radio signals combined with good reconstruction precision. Furthermore, this technique improves the air shower longitudinal reconstruction, which can be used to identify neutrinos with their first interaction far below the top of the atmosphere.

In this work, we investigate the potential for detecting UHE neutrinos using ground-based observatories like the Pierre Auger Observatory. We find that incorporating radio detectors enhances trigger efficiency for inclined air showers induced by neutrinos. Precise reconstruction of the shower maximum position and shower axis is essential for neutrino identification via radio signals. Therefore, we highlight the algorithm specifically developed for reconstructing neutrino-induced showers. Additionally, we model the relationship between radio radiation energy and the total shower energy for neutrino events. Finally, we present the expected neutrino detection sensitivity achievable using radio antennas alone.

Speaker: Baobiao Yue

16:20 Using the Cherenkov Telescope onboard EUSO-SPB2 for Target of Opportunity searches of very high energy neutrino sources

The Extreme Universe Space Observatory on a Super Pressure Balloon 2 (EUSO-SPB2) mission launched from Wanaka New Zealand on May 13 2023. The onboard Cherenkov Telescope (CT) was pointed just below Earth's horizon to conduct Target of Opportunity (ToO) observations, in order to follow up on possible sources of >10PeV neutrinos. For these observations, the earth is used as a tau-neutrino to tau-lepton converter, and the CT searches for optical signals from extensive air showers induced by tau-lepton decays. The EUSO-SPB2 mission lasted ~36h due to a leak in the balloon, resulting in a loss of the payload in the Pacific Ocean. In this contribution, we will present possible neutrino source candidates that crossed the CT's field of view of 6.4° x 12.8° during the two nights of observation, and their associated neutrino fluence limits. These observations demonstrate the viability of conducting ToO follow-up observations from a near space environment. We will present our new software tool designed for scheduling observations, the Neutrino Target Scheduler, and our prospects for conducting ToO searches with the future mission POEMMA Balloon with Radio, a scaled-down version of the Probe Of Extreme Multi-Messenger Astrophysics (POEMMA) design.

Speaker: Claire Guépin-Detrigne (CNRS, LUPM)

16:35 In Situ Calibration Systems for the Pacific Ocean Neutrino Experiment

The Pacific Ocean Neutrino Experiment (P-ONE) is a cubic-kilometer scale neutrino telescope to be deployed in the northern Pacific Ocean off the West Coast of Canada. P-ONE will observe high-energy neutrinos using an array of kilometer tall mooring lines instrumented with P-ONE Optical Modules (P-OMs) which detect Cherenkov light from neutrino-induced secondary particles within the detector volume. To accurately understand the signals from incident neutrinos, the optical properties of seawater, detector geometry, and optical backgrounds must be precisely calibrated. However, the ocean is a dynamic environment where these parameters can vary over time. To achieve this goal, P-ONE includes a variety of calibration systems for both localized and ranged real time detector calibration measurements. These include integrated small, fast light flashers for optical inter-module measurements, acoustic receivers for spatial trilateration, and auxiliary sensors for tilt and orientation measurements. The acoustic positioning system is further complemented with autonomous and cabled acoustic pingers on the seafloor. In addition, some P-OMs in the detector are designed as hybrid calibration modules (P-CALs) which additionally contain long-range, isotropic nanosecond light flashers and cameras. This talk highlights the simulation, development, and field testing of all P-ONE calibration systems.

Speaker: Dilraj Ghuman (Simon Fraser University)

16:50 → 17:04 Break

17:04 → 18:20 GA: unidentified galactic sources

17:04 Discovery of the Gamma-Ray source LHAASO J0534+3535

We report the discovery of an extended γ-ray source named LHAASO J0534+3535 with a significance of about 8 standard deviations for energy from TeVs to tens of TeVs. In addition to the γ-ray source detected by LHAASO, there is only one old supernova remnant candidate, G172.8+1.5, and two 4FGL GeV sources identified within a 4-degree radius of LHAASO J0534+3535. G172.8+1.5 is located in one of the largest star-forming regions in the outer Galaxy, characterized by HI gas that extends to velocities beyond those allowed by Galactic rotation, spanning an area of 4.4 degrees by 3.4 degrees at a distance of 1.8 kpc. LHAASO J0534+3535 is detected in the center of the supernova remnant G172.8+1.5, with an extension of approximately 0.5 degrees, located 0.6 degrees away from the two nearby FGL GeV sources. The multi-wavelength energy spectrum and its upper limits are analyzed using LHAASO and Fermi-LAT data, and are fitted using both hadronic and leptonic models. The results of the data analysis for J0534+3535, as well as its potential correlation with G172.8+1.5 and the two nearby 4FGL sources, will be presented.

Speaker: Xiurong Li

17:19 Observations of TeV Gamma-Ray Sources in the DA 495 Region

The High Altitude Water Cherenkov (HAWC) Observatory has identified three TeV gamma-ray sources in the DA 495 region, a complex area of the Galactic plane that includes the pulsar wind nebula candidate DA 495 and other sources. In this talk, I will present an updated analysis of the morphology and energy spectra of these sources using 2860 days of HAWC data processed with an improved reconstruction algorithm. I will highlight the distinctive properties of each source and explore the potential origins of the observed TeV gamma rays. Additionally, I will discuss prospects for follow-up observations with VERITAS. This future collaborative study will provide a deeper understanding of the emission mechanisms in this region.

Speaker: Mr Seonghyeon Yu (Pennsylvania State University)

17:34 Spectrum and Morphology of the Ultra-High-Energy Source LHAASO~J2018+3651

The LHAASO~J2018+3651 region is one of the brightest sources in the sky at TeV energies. Photons with energies up to ∼0.27 PeV from this region have been detected with the Large High Altitude Air Shower Observatory (LHAASO) and here we present a detailed study of this region using more data from LHAASO. This analysis resolves the region into six sources: LHAASO~J2018+3641, LHAASO~J2019+3649, LHAASO~J2021+3654, LHAASO~J2016+3712, LHAASO~J2013+3610 and LHAASO~J2028+3701. An investigation of the morphology and spectrum for LHAASO~J2018+3641, LHAASO~J2019+3649 and LHAASO~J2021+3654 are the focus of this work. We associate LHAASO~J2019+3649 and LHAASO~J2021+3654 with PSR~J2021+3651 and its X-ray pulsar wind nebula. LHAASO~J2018+3641 with the star formation region Sh 2-104. We associate LHAASO~J2016+3712 with the evolved supernova remnant CTB 87 and LHAASO~J2013+3610 with the evolved supernova remnant G073.9+00.9.

Speaker: Mr Huicai Li (Institute of High Energy Physics, Chinese Academy of Sciences, 100049 Beijing, China)

17:49 Study of HESS J1857 with HAWC for a Multi-wavelength Analysis

The High Energy Stereoscopic System (H.E.S.S.) collaboration reported the emission of two extended sources, HESS J1857+027 and HESS J1858+020, with no known counterparts with an approximate separation of 1 degree. However, in the 3HWC catalog, the High-Altitude Water Cherenkov (HAWC) collaboration reported the emission of 3HWC J1857+027. We present a multi-source fitting analysis of the HESS J1857 region with ~2860 days of observations from the HAWC observatory as part of a multi-wavelength study effort to better understand the emission mechanisms. With the improved performance and enriched statistics, we can now resolve the emission from both sources in the region beyond tens of TeV and observe a cutoff in the emission for J1857 for energies beyond ~30 TeV.

Speaker: Mr Ramiro Torres-Escobedo (Shanghai Jiao Tong University)

18:04 A VERITAS view of HESS J1857+026 within a multi-wavelength analysis

HESS J1857+026 remains a mysterious gamma-ray emitter since its discovery in 2008. Despite the disclosure of a nearby pulsar and multiple studies in the high-energy (HE, E > 100 MeV) and very-high-energy (VHE, E > 100 GeV) regimes, there have been no confirmed counterparts (e.g., an SNR shell or other extended structure) in X-ray or other wavelengths. We present the result of our study of the VHE emission of HESS J1857+026 with VERITAS as part of a multi-wavelength investigation to uncover its emission mechanisms. Our result confirms the extended nature of the source and we characterize its spectral and morphological features in the VHE band. Using the morphology of the source revealed in our analysis, we also explore the underlying transport process of a possible electron population in a leptonic PWN scenario for the gamma-ray emission.

Speaker: Dr Yu Chen

17:05 → 18:35 .

17:05 → 18:20 CRD: experimental results: miscellaneous

17:05 Measuring sub-GeV galactic cosmic ray with HEPD-01 on the CSES-01 satellite

The High-Energy Particle Detector (HEPD-01) is one of the scientific instruments onboard the China Seismo-Electromagnetic Satellite (CSES-01) launched in February 2018. This lightweight and compact payload measures electrons in the 3-100 MeV energy range, protons between 30 and 250 MeV, and light nuclei up to a few hundred MeV per nucleon, using a calorimeter composed of plastic scintillators and LYSO inorganic crystals. Thanks to its wide angular acceptance and the satellite’s polar orbit, HEPD-01 enables the measurement of galactic cosmic-ray spectra on a daily basis for protons.

In this work, we present the measurement of the galactic proton spectrum in the 40-250 MeV energy range and its time evolution, showing the effects of solar modulation over the entire data-taking period. Additionally, we present results of the galactic helium analysis, covering the 60-200 MeV/nucleon energy range. HEPD-01 results are compared with theoretical spectra obtained using the 2D Monte Carlo model HelMod, which simulates the solar modulation of galactic cosmic rays. With the upcoming launch of HEPD-02 onboard the second CSES satellite, we expect to extend this analysis in the near future, enabling a unique and continuous observation of low-energy galactic cosmic rays over a 10-year period and spanning two different solar cycles.

Speaker: Alessandro Sotgiu

17:20 Observations of Low-energy Cosmic-Ray Electron and Positron Spectra with the 2024 AESOP-Lite Mission

As cosmic ray electrons and positrons propagate through the heliosphere, they interact with the outwards-flowing solar wind. The flux of low energy electrons is modulated by this solar wind, resulting in a flux spectrum with a turn-up around 100MeV. The source of this turn-up is unknown, but has been investigated by various cosmic ray detectors at 1AU during different periods of solar activity. One such experiment is the balloon-borne spectrometer AESOP-Lite (Anti-Electron Sub-Orbital Payload Low Energy), which launched from McMurdo Station, Antarctica on January 10, 2024. AESOP-Lite measures the rigidity and charge-sign of downwards-moving particles near the top of the atmosphere, targeting cosmic ray electrons and positrons between 20MeV-1GeV. The 2024 flight lasted around 46 hours, reaching a maximum altitude of 157,551 feet. This was the second flight of AESOP-Lite, the first being out of Kiruna, Sweden in May 2018 during a period of minimum solar activity. We present the low-energy electron and positron flux spectra as measured by AESOP-Lite during its most recent flight, which occurred during a period of high solar activity. Comparisons with the 2018 flight and similar measurements both at 1AU and in local interstellar space reveal the effects of solar modulation on the flux of cosmic ray electrons. We also present the positron fraction of cosmic rays measured during the 2024 campaign. Studying that fraction across our entire energy range allows us to infer about the source of these cosmic rays, and reveals information about the different components of solar modulation.

Speaker: Scott Martin (Bartol Research Institute, University of Delaware Department of Physics and Astronomy)

17:35 Measurement of the Proton and Helium-4 Cross Sections in Space with DAMPE

Hadronic cross sections are one of the dominant sources of uncertainty for the measurement of Galactic Cosmic Ray (GCR) fluxes with calorimetric experiments. Refining these cross sections can serve as an important step towards obtaining a better understanding of GCR production and propagation. This work presents measurements of hadronic cross sections for protons and helium-4 using data from the Dark Matter Particle Explorer (DAMPE).

DAMPE is a satellite-borne experiment designed for the direct detection of cosmic rays. It has been operating in a stable configuration ever since its launch in December 2015. The large dataset of hadronic cosmic-ray events recorded by DAMPE enables cross-section measurements over a broad kinetic energy range, from 20 GeV to 10 TeV. For helium-4 these are the first cross-section measurements at these energies for any heavy target material. The results are used to improve the accuracy of current GCR flux measurements. Additionally, we demonstrate how the results can be scaled to extract the cross section for other heavy target materials.

Speaker: Paul Coppin (Universite de Geneve (CH))

17:50 First Results from the RadMap Telescope

The RadMap Telescope is a compact instrument designed to characterize the primary spectrum of cosmic-ray nuclei and the secondary radiation field created by their interaction with the shielding of spacecraft. Its main purpose is to precisely monitor the radiation exposure of astronauts, and it is the first instrument with a compact form factor that can measure both the charge and energy of individual nuclei with energies up to several GeV per nucleon. This capability is enabled by a tracking calorimeter made from scintillating-plastic fibers, which can record the energy-loss profile of particles in three dimensions and with nearly omnidirectional sensitivity. We present first results from the RadMap Telescope’s first orbital deployment on the International Space Station between April 2023 and January 2024.

Speaker: Martin Jan Losekamm (Technische Universitaet Muenchen (DE))

18:05 Dual cosmic ray detector based on acrylic rods

Cosmic rays are an abundant, and not complete known, natural source of ionizing and photonizing radiation from outer space, where multiple techniques have been invented to detect and study them. In order to detect and study them, we planned, designed and simulated a detection system consisting of two identical detectors based on cylindrical transparent acrylic rods of $20\, cm$ high and $10.16\, cm$ in diameter. We report on the technical details of this cosmic ray detector and some preliminary simulation results obtained using CERN GEANT4.

Speaker: Juan Emmanuel Rosas Trujillo (Laboratorio Internacional de Partículas Elementales, Departamento de Física, DCeI, CL. UGTO)

17:05 → 18:35 DM: indirect detection

17:05 Heavy Dark Matter Annihilation search with IceCube tracks

Dwarf Spheroidal galaxies (dSphs) are suspected dark matter (DM) dense astrophysical objects within our galactic neighborhood. DSphs are otherwise faint high-energy neutrino sources which makes them ideal dark matter targets. An early IceCube dark matter search toward dSphs was performed with an incomplete detector with 59 strings and 339.8 days of livetime. This updated analysis is performed on IceCube's full 86 strings with 10.4 years of data from the Northern Hemisphere. We study a dark matter mass range not well explored ranging from hundreds of GeV to 100 PeV in dark matter mass. We present the current IceCube sensitivity and preliminary limits on the velocity-weighted cross section of annihilating dark matter. We report that our data is consistent with the neutrino background.

Speaker: Dan Salazar-Gallegos

17:20 Dark matter searches in the Galactic Center with IceCube-DeepCore and IceCube-Upgrade

The nature of Dark Matter is one of the important unresolved questions in fundamental physics. It is assumed in many Beyond Standard Model theories that dark matter candidates can have weak coupling to Standard Model (SM) particles. In heavy cosmological objects, like galaxies, the Sun, or the Earth, dark matter can be gravitationally accumulated in high abundance. Then, the DM can decay or annihilate into the anomalous flux of SM particles detectable by various detector types. In this contribution, I will present a recent search for neutrino signals from GeV-scale Dark Matter in the Galactic Center with the IceCube-DeepCore. I will also discuss the prospect of such a search with the IceCube-Upgrade, an upcoming extension of the IceCube Neutrino Observatory to enhance performance in the GeV energy range.

Speaker: Nhan Chau (IIHE, Brussels)

17:35 Indirect dark matter searches towards the Sun using the full ANTARES data set

Weakly Interacting Massive Particles (WIMPs) are among the most compelling candidates for particle dark matter. These particles can be gravitationally captured by massive celestial bodies, such as the Sun, where they accumulate and, according to theoretical models, eventually self-annihilate into Standard Model particles, including neutrinos. Neutrino telescopes - large arrays of photo-sensors in a transparent medium - can search for this indirect signature of dark matter by detecting neutrinos originating from the Sun’s core.
In this study, data collected from 2007 to 2022 by ANTARES, a neutrino telescope in the Mediterranean Sea, are analyzed to perform an indirect search for dark matter from the direction of the Sun. Neutrino event properties are reconstructed using standard algorithms developed within the Collaboration, alongside a novel Machine Learning tool designed to enhance reconstruction accuracy for neutrino energies below 200 GeV, applied for the first time in this type of analysis. Additionally, all-flavor neutrino interactions are considered. A likelihood-based unbinned analysis is conducted to determine the upper limits to the spin-dependent and spin-independent WIMP- nucleon scattering cross-sections for WIMP masses ranging from 35 GeV/c$^2$ to 10 TeV/c$^2$ and for three different annihilation channels.

Speaker: Chiara Poirè (Università degli studi di Salerno)

17:50 Neutrino production in the central dark-matter spikes of active galaxies

Recent multi-messenger observations suggest that high-energy neutrinos may be produced close to central black holes in active galaxies. These regions may host dark-matter (DM) spikes, where the concentration of DM particles is very high. Here we explore the contribution of the DM annihilation to the target photons for the neutrino production, proton-photon interactions, estimate the associated neutrino spectrum and figure out possible future tests of this scenario.

Speaker: Polina Kivokurtseva (INR RAS; MSU)

18:05 Limits on WIMP-Scattering Cross Sections using Solar Neutrinos with Ten Years of IceCube Data

Although dark matter (DM) comprises 85% of the matter content of the Universe, its nature remains unknown. One broad class of particle DM motivated by extensions of the Standard Model (SM) is weakly interacting massive particles (WIMPs). Generically, WIMPs will scatter off nuclei in large celestial bodies such as the Sun, thus becoming gravitationally bound. Subsequently, WIMPs can annihilate to stable SM particles, ultimately releasing most of their energy as high-energy neutrinos which escape from the Sun. Thus, an excess of neutrinos from the Sun's direction would be evidence for WIMPs. The IceCube Neutrino Observatory is well-suited to such searches since it is sensitive to WIMPs with masses in the region preferred by supersymmetric extensions of the SM. I will present the results of IceCube's most recent solar WIMP search, which includes all neutrino flavors, covers the WIMP mass range from 10 GeV to 10 TeV, and has world-leading sensitivity over this entire range for most channels considered.

Speaker: Jeffrey Lazar

18:20 WIMP Dark Matter Searches from the Galactic Centre with KM3NeT

Weakly Interacting Massive Particles (WIMP) are interesting dark matter (DM) candidates because they exhibit the usual DM properties (such as being non-relativistic and electrically neutral), while having the advantage of weakly interacting with Standard Model particles, which makes them detectable in principle. When DM decays or annihilates, neutrinos are produced. Therefore, an indirect detection of DM involves searching for an excess of neutrinos in astrophysical targets such as the Galactic Centre or the Sun, where large amounts of DM are believed to accumulate. Such an excess of neutrinos could then be observed by large-scale Cherenkov detectors such as KM3NeT, which is currently under construction in the abyss of the Mediterranean Sea, while taking data in partial detector configurations. KM3NeT is composed of two undersea Cherenkov neutrino detectors: KM3NeT/ORCA, a dense-geometry detector optimised for the measurement of low energy (GeV) neutrinos, and KM3NeT/ARCA, a cubic kilometer-sized detector, intended for the detection of high energy astrophysical neutrinos. In this contribution, we present an un-binned likelihood analysis looking for WIMP-like DM annihilations occurring at the Galactic Centre, where we consider DM with masses ranging from approximately 10 GeV up to 100 TeV. We use data from various partial ORCA-detector configurations with 6, 10, 11 and 15 lines to explore the low DM mass region. For the higher DM mass regions, we use data from the KM3NeT/ARCA detector with 8, 19 and 21 lines. Finally, we show the combined results with the latest analysis from ANTARES, KM3NeT’s predecessor.

Speaker: Adriana Bariego-Quintana (IFIC, Valencia.)

17:05 → 18:35 GA: instrtument higlights & catalogues

17:05 Highlights from MACE

The Major Atmospheric Cherenkov Experiment (MACE) has been conducting
regular observations of very high-energy (VHE) gamma-ray sources since
2021. MACE has successfully detected gamma-ray emission from the standard
candle Crab Nebula, with its measured differential energy spectrum in
agreement with earlier results from similar telescopes. In addition to the
Crab Nebula, MACE has also detected VHE gamma-ray emission from several
sources, including Mrk 501, Mrk 421, and 1ES 1959+650. It was also
deployed for VHE emission searches from a sample of six high-redshift
blazars (0.3 < z < 0.998), for which upper limits on the integral flux
were estimated. MACE detected two episodic VHE gamma-ray activity from the
radio galaxy NGC 1275 in December 2022 and January 2023 and another
enhanced gamma-ray activity on January 25, 2025. Furthermore, on January
26, 2025, MACE detected VHE gamma-ray flare from the flat-spectrum radio
quasar (FSRQ) OP 313.

In this contribution, we will present key scientific results from MACE
over the past four years.

Speaker: Chinmay Borwankar for MACE collaboration (Bhabha Atomic Research Center)

17:20 Highlights from the Tibet AS$\gamma$ experiment

The Tibet AS$\gamma$ experiment, observing cosmic rays/gamma rays above a few TeV, is located at 4,300 m above sea level, in Tibet, China. The experiment is composed of a 65,700 m$^{2}$ surface air shower array and 3,400 m$^{2}$ underground water Cherenkov muon detectors. The surface air shower array is used for reconstructing the primary particle energy and direction, while the underground muon detectors are used for discriminating gamma-ray induced muon-poor air showers from cosmic-ray (proton, helium,...) induced muon-rich air showers.Furthermore,the underground muon detectors turn out to be effective to select the proton component in cosmic rays. We present recent results on sub-PeV cosmic gamma-ray observation, primary cosmic-ray spectrum around the Knee energy region, and cosmic-ray anisotropy from the Tibet AS$\gamma$ experiment.

Speaker: Dr Masato Takita (ICRR, The University of Tokyo)

17:35 Searches for steady and transient Gamma Ray sources with GRAPES-3

The GRAPES-3 experiment, located at an altitude of 2200 metres in, Ooty, Southern India (11.4°N, 76.7°E, 2200 m a.s.l.), records extensive air showers in the TeV–PeV energy range using an array of 400 plastic scintillator detectors arranged in a hexagonal grid over an area of 25,000 m², along with a 560 m² muon detector made of proportional counters. The latter allows showers initiated by gamma rays to be distinguished from those originating in Cosmic Rays. We utilize a graph neural network to isolate a sample of gamma-ray like events from 10 years of archival data and employ an unbinned maximum likelihood estimator to search for point sources. We report on investigations of steady emission from the Crab Nebula as well as a search for transient events.

Speaker: Mr Mohan Karthik

17:50 The Fourth HAWC Catalog of Very-High-Energy Gamma-Ray Sources

We present an updated catalog of TeV gamma-ray sources using data from the 5th reconstruction pass of data from the High Altitude Water Cherenkov Observatory (HAWC). In addition to improved reconstruction and nearly three years of additional data, this new catalog uses a systematic multi-source fitting procedure to model the data with much greater flexibility and accuracy. Besides including a broader variety of source morphologies and spectral shapes than previous HAWC catalogs, this catalog uses a robust modeling of galactic diffuse TeV emission through the HERMES package. This catalog reports 85 sources at the 25 TS threshold including 11 sources not associated with any TevCat source using a distance-based association criterion. Additionally, there are 12 sources not associated with any physical counterpart in Low or High Mass X-ray Binary, the ATNF or Fermi pulsar, or SNR catalogs of sources. Five of the aforementioned sources have no counterpart in any of the catalogs searched and represent new sources of considerable interest.

Speaker: Samuel Groetsch (University of Wisconsin-Madison)

18:05 Steps toward the 5FGL Fermi-LAT source catalog

The current Fermi-LAT source catalog (4FGL-DR4: 7194 sources over 14 years) was built incrementally from the 8-year catalog by adding newly discovered sources but keeping the positions of existing sources fixed. Now, after 16 years (reached in August 2024) there are twice as many data as used in the original 4FGL catalog, enabling much more precise source positions. It is thus time to generate a new original catalog (5FGL). Like the incremental catalogs, this will contain the new sources detectable with the additional two years of data; but unlike the incremental catalogs it will require revision of the existing source names (derived from their coordinates) and a review of associations with counterparts at other wavelengths.

The systematic errors due to our imperfect knowledge of the Galactic diffuse emission, which dominates the gamma-ray sky, are the major limiting factor of the sensitivity and quality of the point source catalog at low energies (a few 100 MeV over the extragalactic sky, up to a few GeV in the Galactic ridge). Two parallel efforts are ongoing to improve on this situation, using more advanced methods to modulate the interstellar gas templates with the LAT data themselves.

I will summarize those efforts toward a new interstellar emission model and present an early 16-year source list (FL16Y) that relocalizes all sources and improves a few aspects of the catalog analysis, but still uses the same diffuse model as 4FGL-DR4.

Speaker: Jean Ballet (AIM, CEA Saclay)

18:20 Dissecting the Gamma-Ray Sky at High Latitudes with Simulation-Based Inference

Over the past 16 years, the Fermi Large Area Telescope (LAT) has significantly advanced our view of the GeV gamma-ray sky, yet several key questions remain - such as the nature of the isotropic diffuse background, the properties of the Galactic pulsar population, and the origin of the GeV excess towards the Galactic Centre. Addressing these challenges requires sophisticated astrophysical modelling and robust statistical methods capable of handling high-dimensional parameter spaces.
In this work, we analyse 14 years of high-latitude ($|b|>30^{\circ}$) Fermi-LAT data in the 1–10 GeV range using simulation-based inference (SBI) via neural ratio estimation. This approach allows us to detect individual gamma-ray sources and derive a source catalogue with estimated positions and fluxes that are consistent with the bright portion of the Fermi-LAT collaboration's 4FGL catalogue. Additionally, we reconstruct the source-count distribution, $\mathrm{d}N/\mathrm{d}S$, in both parametric and non-parametric forms, achieving good agreement with previous literature results and detected sources. We also quantitatively validate our gamma-ray emission simulator via an anomaly detection technique, demonstrating that the synthetic data closely reproduces the complexity of the real observations.
This study highlights the practical utility of SBI for complex, high-dimensional problems in gamma-ray astronomy and lays the groundwork for its application to more challenging sky regions or data from next-generation facilities such as the Cherenkov Telescope Array Observatory.

Speaker: Noemi Anau Montel (Max Planck Institute for Astrophysics)

17:05 → 18:05 NU: atmospheric interpretations & MM studies

17:05 Photo-hadronic pair creation and neutrino production in magnetospheric current sheets of accreting black holes

Non-jetted AGN exhibit hard X-ray emission with a power law spectrum above $\sim$2 keV, which is thought to be produced through Comptonization of soft photons by electrons and positrons (pairs) in the vicinity of the black hole. The origin and composition of this plasma source, known as the corona, is a matter open for debate.
Our study focuses on the role of relativistic protons accelerated in black-hole magnetospheric current sheets in the pair enrichment and neutrino production of AGN coronae. We present a model that has two free parameters, namely the proton plasma magnetization $\sigma_{\rm p}$, which controls the peak energy of the neutrino spectrum, and the Eddington ratio $\lambda_{\rm Edd}$ (defined as the ratio between X-ray luminosity $L_{\rm X}$ and Eddington luminosity $L_{\rm Edd}$), which controls the amount of energy transferred to secondary particles.
Our results indicate a strong dependence of the secondary pair density on the Eddington ratio. More specifically, when $\lambda_{\rm Edd}$ exceeds a critical value $\lambda_{\rm Edd, crit} \propto \sigma_{\rm p}^{-1}$, in which photohadronic interactions in the magnetospheric region can produce enough secondary pairs to create coronae with Thomson optical depths, $\tau \sim 0.10 - 10$. We also present the predicted high-energy neutrino spectrum and discuss our results in light of the recent IceCube observations of TeV neutrinos from NGC 1068, NGC 4151 and CGCG 420-015. Moreover we apply our model on a population of non-blazar AGN sources providing a prediction of the stacked neutrino flux. The latter analysis lies below the IceCube upper limits with NGC 1068 being one of the most dominant contributors to the stacked spectrum.

Speaker: Despina Karavola (National and Kapodistrian University of Athens)

17:20 Neutrino and electromagnetic signals from tidal disruption events: bridging the theory with observations

This presentation covers recent results from the joint analysis of neutrino and electromagnetic cascade emissions from neutrino-coincident tidal disruption events (TDEs), using both an isotropic wind model and relativistic jets. We discuss constraints from Fermi gamma-ray upper limits on the size of the radiation zone and on the maximum energies of accelerated cosmic rays, and the resulting neutrino emissions. Additionally, we explore multi-wavelength modeling of jetted TDEs with luminous X-ray afterglows, incorporating jet and wind dynamics with time-dependent energy injection. We also examine the connection between neutrinos and their multi-wavelength counterparts, highlighting implications for future multi-messenger discoveries with IceCube, IceCube-Gen2, KM3NeT, and Fermi.

Speaker: Chengchao Yuan (Deutsches Elektronen-Synchrotron DESY)

17:35 A neutrino flare associated with X-ray emission from TDE ATLAS17jrp

Tidal disruption events (TDEs), where stars are captured or tidally disrupted by supermassive black holes, are potential astrophysical sources of high-energy neutrinos. We report the discovery of a potential neutrino flare associated with ATLAS17jrp, which occurred 19 days after the onset of the X-ray emission and lasted 56 days. The best-fit spectrum of the neutrino flare follows a power law with a spectral index of $\rm{\gamma=2.7\pm0.4}$ and a flux normalization of $\rm{\Phi_0 =1.9^{+7.2}_{-1.7}\times 10^{-18}\;GeV^{-1} cm^{-2} s^{-1}}$ at 100 TeV, spanning an energy range from 100 GeV to 1 EeV in an analysis of 10 years of IceCube track data. The neutrinos can be produced by the interaction of X-ray photons produced by the hot corona with high-energy particles accelerated by disk winds or outflows. We calculate that the probability of detecting a neutrino flare with a higher test statistic (TS) and a shorter time delay relative to the X-ray emission by chance is $0.4\%$. Therefore, ATLAS17jrp is the second unambiguous TDE (excluding candidates) potentially linked to high-energy neutrinos, following the TDE AT2019dsg associated with an IceCube neutrino alert.

Speaker: Ms Ronglan Li

17:50 Results from IceCube Searches for High-Energy Neutrinos Coincident with Gravitational-Wave Alerts in LVK O4

Gravitational-wave events from mergers of compact objects, both binary black holes and mergers including at least one neutron star, are a predicted source of high-energy neutrinos. In addition to their electromagnetic counterparts, particles accelerated during the compact object coalescence may also interact to produce high-energy neutrinos. The LIGO-Virgo-KAGRA Collaboration sends candidate gravitational wave events from compact binary coalescences publicly in real time during the current observing run (O4). Using data from the IceCube Neutrino Observatory, we search for neutrinos spatially and temporally coincident with these gravitational wave candidate events using a time window of 1000 seconds centered on the merger time. We use two methods, both of which have been previously used to search for neutrino emission from gravitational-wave transients: an unbinned maximum likelihood analysis applied to significant alerts and a Bayesian analysis with astrophysical priors, applied to both significant and low-significance alerts. In addition, we search for long-duration neutrino emission up to 14 days after the merging of binaries containing a neutron star. We report analysis results determined in real time for these searches, and set upper limits on both flux and isotropic-equivalent energy emitted in neutrinos.

Speaker: Zsuzsanna Marka

17:05 → 18:35 NU: experimental & next generation

17:05 Measurement of the Diffuse Astrophysical Neutrino Spectrum above a TeV with All Flavor Starting Events in IceCube

The IceCube Neutrino Observatory utilizes the Cherenkov radiation emitted by charged secondary particles produced in interactions of neutrinos with ice nucleons to detect neutrino events. “Starting events”, where this interaction vertex is contained inside the detector volume, can be used to distinguish neutrinos from the dominant background of atmospheric through-going muons. We present the Medium Energy Starting Events (MESE) selection, which employs a series of vetoes to obtain a neutrino-pure sample to measure the flux of diffuse extragalactic neutrinos from 1 TeV to 10 PeV from the entire sky. In this talk we will present a measurement of the spectrum of the diffuse flux of neutrinos, which demonstrates strong evidence for structure in the spectrum beyond a single power law, rejecting the single power law hypothesis by 4σ.

Speaker: Vedant Basu

17:20 Measurement of the Three-Flavor Composition of Astrophysical Neutrinos with Contained IceCube Events

The IceCube Neutrino Observatory at the South Pole detects neutrinos from the entire sky, both of astrophysical and atmospheric origin, via the Cherenkov light emitted when these neutrinos interact in the ice, giving rise to rapidly moving charged particles. Neutrino events with vertices contained within the detector volume are useful for studying the neutrino flavor ratio, as they allow for a better reconstruction of the event morphology. The Medium Energy Starting Events (MESE) data sample selects events with vertices contained inside the detector volume, also known as starting events, with energies of at least 1 TeV. This sample naturally includes electron-, muon-, and tau-neutrino events, processed consistently. We use it to constrain the flavour ratio of astrophysical neutrinos at Earth, which in turn informs us of the flavour composition at the source itself. In this talk, we will present the results of this study, which uses 11.4 years of IceCube data.

Speaker: Aswathi Balagopal V. (University of Delaware)

17:35 Neutrino Flavor Identification at the Highest Energies with PUEO

PUEO (the Payload for Ultra-high Energy Observations) is an Antarctic, balloon-borne experiment that aims to detect neutrinos above EeV energies primarily by searching for Askaryan radiation sourced from particle cascades induced by interactions within the ice. At the highest energies, neutrinos predominantly undergo charged-current interactions, producing high energy charged leptons which can induce secondary cascades during their propagation. PUEO is particularly sensitive to these secondary cascades for 2 reasons: i) high altitude observations provide long distances (O(100km)) to observed radiation, ensuring similar angles to the payload. This geometry allows for multi-pulse topology to occur readily within single detection windows ii) the pulse shape produced by Askaryan emission is dependent on interaction type (hadronic/electromagnetic/hybrid) and differentiation can point to charged-lepton flavor identification. In this talk, we discuss PUEO's ability to measure and characterize secondary cascades in ice, moving towards a robust method for neutrino flavor identification at the highest energies. We also discuss how PUEO's characterization of these secondary cascades helps to constrain neutrino energy and direction, both of which are crucial for multi-messenger based observations.

Speaker: Christoph Welling (University of Chicago)

17:50 Do cosmic rays produce in-ice Askaryan radiation? A study with the Askaryan Radio Array

Radio detection is the most promising experimental strategy to study the extremely low flux of EeV-scale neutrinos from the cosmos. Neutrinos interacting in the polar ice sheets produce electromagnetic radiation through the Askaryan mechanism, which is detectable at long distances by radio antenna arrays embedded in the ice. While Askaryan radio emission from neutrinos has yet to be observed, cosmic rays provide an opportunity to understand the characteristics of this emission in nature.

In this contribution, we use data from the Askaryan Radio Array (ARA) to present a detailed experimental study targeting radio emission from high-energy particle cascades in glacial ice. We analyze events consistent with near-vertical cosmic-ray air showers impacting the ice near the detector, which would typically be considered a background in neutrino searches. Our analysis determines polarization, frequency content, and signal shape of the observed candidate events and performs comparisons with ab-initio simulations of in-ice radiation from a dense shower core. If confirmed, these findings would provide direct experimental validation of the Askaryan emission mechanism central to ARA and other radio neutrino observatories.

Speaker: Philipp Windischhofer (University of Chicago (US))

18:05 Study of an Isolated Double-pulse Cosmic Ray Candidate Recorded with the Askaryan Radio Array

The radio-frequency emissions produced by particle showers on Earth, resulting from cosmic rays (CRs) and neutrinos originating from highly energetic sources, share significant similarities, enabling radio detectors initially designed for ultra-high energy neutrino (UHE-$\nu$) searches to also study CRs. The Askaryan Radio Array (ARA), an experiment currently operating within the ice at the South Pole, is primarily designed to detect UHE-$\nu$s. To date, ARA has deployed five stations, with each station equipped with antennas installed up to a depth of 200 meters in the ice.
Data recorded by ARA Station-2 (A2) suggests a potential CR origin for a subset of events identified in a UHE-$\nu$ search, including a double-pulse event potentially from a downward propagating CR-induced air shower, with geomagnetic followed by Askaryan emission producing the two pulses. A detailed investigation of this CR candidate event using comprehensive simulations is underway to accurately determine the origin of the event, with the goal of identifying the parameters of a CR-induced air shower that best match the experimentally observed quantities. We simulate predicted CR signals in ARA by combining a modern impacting CR shower simulation framework (FAERIE) with a realistic detector simulation (AraSim).
We will present results for an optimization of the event topology, identified through simulated CR showers, comparing the vertex reconstruction of both the geomagnetic and Askaryan signals of the event, as well as the observed time delays between the two signals in each channel.

Speaker: Shoukat Ali (University of Kansas)

18:20 Cosmic-Ray Physics in the PeV to EeV Energy Range with the IceCube-Gen2 Surface Array

IceCube-Gen2 is a proposed neutrino observatory at the South Pole that will build on the success of IceCube and will also serve as a unique detector for cosmic-ray air showers.
Analogous to the IceTop surface array over IceCube’s deep optical detector, IceCube-Gen2 will also feature a surface array above an optical array deep in the ice. As improvement over IceTop, the IceCube-Gen2 surface array will be comprised of elevated detectors to avoid snow coverage, and will combine two types of detectors: scintillation panels that measure air-shower particles on ground and enable a low detection threshold, which is important to serve as a veto for selecting downgoing neutrino candidates; and radio antennas which increase the measurement accuracy for air showers by providing a calorimetric measurement of the electromagnetic shower component and its depth of maximum, X_max. As another major advantage, the eight times larger surface area combined with a larger field of view will provide a 30-fold increase for the aperture of surface-deep coincident events. With these improvements in statistics and measurement accuracy, IceCube-Gen2 will thus make unique contributions to the particle physics and astrophysics of Galactic cosmic rays in the PeV to EeV energy range, including the search for PeV photon sources. This proceeding will summarize the technical design and science case enabled by the IceCube-Gen2 Surface Array.

Speaker: Frank Schroeder (Bartol Research Institute, Department of Physics and Astronomy, University of Delaware; and Institute for Astroparticle Physics, Karlsruhe Institute of Technology)

20:00 → 23:30 Conference dinner

Wednesday 23 July

08:30 → 09:00 Registration

09:00 → 10:30 Plenary session

09:00 Astrophysical probes of dark matter

The microscopic nature of dark matter is one of the greatest mysteries of modern science. On the other hand, the best-motivated particle dark matter candidates will be definitively probed in the coming years by a combination of laboratory and astrophysical probes. In this review I will focus on present-day and near future efforts to use astrophysical observations, for example in the gamma-ray band, to indirectly detect the microscopic nature of motivated dark matter candidates including the QCD axion and minimal thermal dark matter candidates like the higgsino.

Speaker: Benjamin Ryan Safdi

09:45 extragalactic jets

10:30 → 11:00 Coffee

11:00 → 12:00 Plenary session

11:00 eht

11:30 Quasi-periodic eruptions and tidal disruptions: transients illuminating the environments of massive black holes

Quasi-periodic eruptions (QPEs) are high-amplitude, soft X-ray flares that repeat on timescales of hours-days, and have been discovered recently in the nuclei of some galaxies. These remarkable and mysterious repeating transients are thought to be associated with the supermassive black holes in these galaxies. QPEs have could provide powerful new constraints on accretion physics (if caused by disk instabilities) or on orbital dynamics within the central ~1 AU (if caused by interactions with nearby stars). Several lines of evidence, both observational and theoretical, have suggested a connection with tidal disruption events (TDEs), where stars within the black hole loss cone are destroyed by tidal forces. In this talk I will give an overview of the observational properties of QPEs, and the reasons to suspect a connection with TDEs. I will then show the first definitive proof of this connection, the implications for QPE emission mechanisms, and the promise for upcoming gravitational wave detectors including LISA.

Speaker: Dr Matt Nicholl (Queen’s University Belfast)

12:00 → 13:20 Lunch

13:20 → 14:50 CRI: spectrum

13:20 Measurement of the cosmic-ray energy spectrum with the TALE detector in hybrid mode

The TA Low-energy Extension (TALE) experiment extends the reach of the TA experiment on the low-energy side to below $10^{16}$ eV. A primary objective of TALE is to study the transition from galactic to extragalactic cosmic rays. The TALE detector is a hybrid observatory composed of fluorescence telescopes and a surface detector array of scintillation counters. The surface detectors are arranged with inter-counter spacing optimized for hybrid energy spectrum measurements in the low-energy region. We analyzed data collected between November 2018 and May 2023, corresponding to 1,247 hours of operation, and in this presentation, we will show the results of the cosmic ray energy spectrum measurement using the TALE hybrid detector. This measurement will play an important role in understanding the transition from cosmic rays of galactic origin to those of extragalactic origin.

Speaker: Dr Hitoshi Oshima (Institute for Cosmic Ray Research, The University of Tokyo)

13:35 Evaluation of the systematic uncertainties of the cosmic ray energy spectrum measured by the Telescopa Array surface detector array

The surface detector (SD) array of the Telescope Array (TA) experiment, covering an area of 700 km$^2$ with 507 plastic scintillators, observes ultra-high-energy cosmic rays (UHECRs). In this presentation, we discuss the evaluation of various systematic uncertainties in the cosmic ray energy spectrum measured by the TA SD array, including those arising from the choice of hadronic interaction models and the mass composition of UHECRs.

Speaker: Kozo Fujisue

13:50 Analysis of Inclined Air Shower Events Observed by the TA SD and the TAx4 SD

The Telescope Array (TA) experiment has been observing extensive air showers (EAS) induced by ultrahigh energy cosmic rays (UHECR) since 2008. The TAx4 upgrade aims to expand the detection area of TA at the highest energies to four times its original size with 500 additional surface detectors (SD) with the nearest neighbor spacing extended from 1.2km to 2.08km. Half of the new detectors were installed in 2019, and have been operating since then. The objective of the upgrade is to significantly increase the number of events for analysis. In addition to the physical expansion, TA is also investigating improvements to its reconstruction procedure. In particular TA has previously accepted events only up to a maximum zenith angle of 55 degrees. In this paper we describe the results of extending the acceptance to 65 degrees in zenith, which required the energy estimation table to be expanded to include simulated events up to 70 degrees in zenith. To validate the accuracy of the simulation, which is crucial for both the energy estimation and for the calculation of detector acceptance, we compared distributions of key parameters between observed and simulated TAx4 data. We confirmed that there was no significant discrepancy between the two, in particular for the extended range of zenirth angles. We also show the measured TAx4 SD energy spectrum, including large zenith angle events based on three years of observation. Finally, we applied the extension to the TA SD analysis, generating a new energy estimation table for zenith angles up to 70 degrees. We also compared the observed and simulated TA SD data and validated the method.

Speaker: Chisato Koyama (ICRR, The University of Tokyo)

14:05 Updated comparison of the UHECR energy spectra measured by the Pierre Auger Observatory and the Telescope Array

The Pierre Auger -Telescope Array joint working group on the UHECR energy spectrum was established in 2012 to analyze energy scale uncertainties in both experiments and to investigate their systematic differences, particularly in the spectral shape of the flux measurements. Previous studies have indeed shown that, within systematic uncertainties, the energy spectra measured by the two observatories are consistent below 10 EeV. However, at higher energies, a significant difference remains in the common declination band. In this work, we re-examine this discrepancy in greater detail and explore its possible origins. We consider systematic and statistical uncertainties, including the conversion from directly measured observables to energy and the calculation of exposures. We present an updated energy scale comparison between the two experiments and updated flux measurements in the common declination band.

Speaker: Francesco Salamida

14:20 Measurement of the cosmic-ray energy spectrum above 2.5 EeV using 19 years of operation of the Pierre Auger Observatory

We present the spectrum of cosmic rays with energies above 2.5 EeV measured at the Pierre Auger Observatory after 19 years of operation, covering the period before the AugerPrime upgrade. Two independent event sets from the surface array of 1500 m-spaced detectors are combined, yielding a total exposure of approximately 100,000 km² sr yr. The first set includes events with zenith angles less than 60°, while the second consists of events between 60° and 80°, for which azimuthal asymmetries must be accounted for in the energy estimator. The threshold energy is chosen to ensure a trigger efficiency of the surface detector greater than 97%, thus minimizing composition biases. The energy scale is determined using high-quality fluorescence measurements, providing calorimetric estimates without reliance on simulations.

A statistically successful combination is achieved within the uncorrelated systematic uncertainties of the individual spectra. All spectra are consistent when analyzing potential declination dependences, except for a mild modulation expected from the previously reported dipolar anisotropy. In particular, this statement applies to the northernmost declination band [+25°,+45°], where only contribute events with zenith angles between 60° and 80°. Beyond the firmly established ankle and suppression spectral features, the combined spectrum across declinations -90° to +45° provides high-precision measurements of the instep feature with more than 5σ confidence.

Speaker: Diego Ravignani

14:35 Features in the Cosmic Ray Energy Spectrum Observed with Telescope Array Surface Detectors

Ultra-high energy cosmic rays (UHECRs) are extremely energetic charged particles that originate from outer space. The Telescope Array (TA) experiment, the largest UHECR observatory in the Northern Hemisphere, has provided high-precision measurements of the cosmic ray energy spectrum due to its stable operation and efficient data collection. These measurements have revealed three significant spectral features: the ankle, shoulder, and cutoff. Analyzing these features is crucial for understanding the origin and propagation of UHECRs. In this talk, we will present the latest energy spectrum measured by the TA surface detectors and discuss the observed differences in the UHECR energy spectrum between the northern and southern skies.

Speaker: Jihyun Kim

13:20 → 14:50 DM: primordial black-holes & accelerators

13:20 Cosmic antimatter signatures from primordial back holes

In this talk, we present our study of the cosmic antiproton and antideuteron fluxes produced by the evaporation of galactic primordial black holes (PBHs). The antimatter production spectra were obtained using our modified version of the BlackHawk code, which incorporates a state‐of‐the‐art Wigner function coalescence model for antideuteron formation. The propagation of these fluxes throughout the Galaxy is computed with the USINE code, employing the latest cosmic-ray propagation frameworks. Using a realistic treatment of theoretical uncertainties and experimental errors, we compared our predicted antiproton fluxes with AMS‑02 measurements and background predictions and we derived competitive bounds on the abundance of PBHs in the window of critical masses of 10¹² to 10¹⁸ grams, limiting the parameter space for PBHs as Dark Matter candidates. Finally, we compared the predicted antideuteron fluxes with the expected sensitivity of the GAPS experiment, to probe its potential to detect antideuterons of PBH origin.

Speaker: Lorenzo Stefanuto (University of Turin)

13:35 An all-sky search for individual Primordial Black Hole burst with LHAASO

Primordial Black Holes~(PBHs) are hypothetical black holes with a wide range of masses that formed in the early universe. As a result, they may play an important cosmological role and provide a unique probe of the early universe.
A PBH with an initial mass of approximately $10^{15}$~g is expected to explode today in a final burst of Hawking radiation. In this work, we conduct an all-sky search for individual PBH burst events using the data collected from March 2021 to July 2024 by the Water Cherenkov Detector Array of the Large High Altitude Air Shower Observatory. Three PBH burst timescales, 1~s, 10~s, and 100~s, are searched, with no significant PBH bursts observed. The upper limit on the local PBH burst rate density is set to be as low as 202~pc$^{-3}$yr$^{-1}$ at 99$\%$ credibility level, representing the most stringent limit achieved to date.

Speaker: Dr Houbing Jiang (Institute of High Energy Physics, Chinese)

13:50 Revisiting Primordial Black Hole Capture by Neutron Stars

A sub-solar mass primordial black hole (PBH) passing through a neutron star, can lose enough energy through interactions with the dense stellar medium to become gravitationally bound to the star. Once captured, the PBH would sink to the core of the neutron star, and completely consume it from the inside. In our research, we improve previous energy-loss calculations by considering a realistic solution for the neutron star interior, and refine the treatment of the interaction dynamics and collapse likelihood. We then consider the effect of a sub-solar PBH population on neutron stars near the Galactic center. We find that it is not possible to explain the lack of observed pulsars near the galactic center through dynamical capture of PBHs, as the velocity dispersion is too high. We then show that future observations of old neutron stars close to Sgr A* could set stringent constraints on the PBHs abundance. These cannot however be extended in the currently unconstrained asteroid-mass range, since PBHs of smaller mass would lose less energy in their interaction with the neutron star and end up in orbits that are too loosely bound and likely to be disrupted by other stars in the Galactic center.

Speaker: Roberto Caiozzo (SISSA)

14:05 Search for Beyond Standard Model Physics with FASER at the LHC

FASER (the Forward Search Experiment) is a compact detector located about 480 m downstream of the ATLAS interaction point at CERN’s Large Hadron Collider (LHC). It is designed to explore new Beyond the Standard Model (BSM) physics by searching for light, weakly interacting, and long-lived particles (LLPs) produced in the far-forward region. This unique setup—shielded by approximately 100 m of rock and concrete—enables FASER to perform highly sensitive searches for exotic states such as dark photons (A′) and axion-like particles (ALPs), potentially mediating interactions between the visible and dark sectors. During Run 3 (2022–2024), FASER has recorded 190 fb⁻¹ of data with over 97% efficiency, and A dark photon and ALP searches are performed. We will present these physics results, probing previously unexplored mass and coupling ranges. FASER is now planning an upgrade of its preshower sub-detector to improve diphoton resolution and background discrimination, aiming for enhanced sensitivity in upcoming ALP and other new physics searches. With continued data collection through Run 3 and a substantially increased data set during the High-Luminosity LHC era (Run 4), FASER will further extend its discovery potential for long-lived particles and other novel BSM signatures. In this talk, we will present the status of the experiment, including detector design, detector performance, and physics results of new particle searches from Run 3 data.

Speaker: Tomohiro Inada (Kyushu University (JP))

14:20 Searching for massive, non-relativistic particles in space with the SQM-ISS detector

SQM-ISS is a detector that will look for massive particles among cosmic rays from the International Space Station. Some of these candidates include strange quark matter, Q-balls, lumps of fermionic exotic compact stars, primordial black holes, mirror matter, Fermi balls and others. These compact and dense objects are expected to be much heavier than normal nuclei, to travel at speeds typical of objects on their way to the centre of a galaxy, and to be able to penetrate deeply.
Some of these particles might account for all or part of the non-baryonic dark matter inferred by cosmology without requiring new fundamental physics.
The SQM-ISS detector is made up of a layer of scintillator and piezoelectric elements that provide information on both charge state and mass.
Experimental tests have validated its ability to discriminate between particle types based on charge and velocity measurements (v $<$ 250 km/s), with timing data further supporting velocity determination.
The experiment was already chosen by ESA through the Open Space Innovation Platform.
The integration of advanced data acquisition and real-time processing systems further enhances operational reliability, ensuring accurate measurements in the challenging space environment.
This effort not only advances detector technology, but also opens the way to explore fundamental questions about the composition and evolution of the universe.
The experimental results are expected to provide crucial insights into the dynamics of non-standard cosmic ray components, potentially revising our understanding of high-energy astrophysics and the search for new states of matter beyond the Standard Model.
In this work I will describe the detector, its observational capabilities and its potential for advancing our understanding of exotic cosmic particles.

Speaker: Zbigniew Plebaniak (INFN Rome and University of Rome, Tor Vergta, Italy)

14:35 Search for Sub-Relativistic Magnetic Monopoles with the IceCube Neutrino Observatory

Magnetic monopoles are beyond standard model particles, predicted by Grand Unified Theories (GUTs) to be created during the early universe. At typical masses of the GUT-scale - above $10^{14}$ GeV - these particles would move at sub-relativistic speeds. The Rubakov-Callan effect predicts that magnetic monopoles can catalyze nucleon decays, in particular the decay of protons. This results in a unique signature of small particle cascades along the trajectory of the slow moving magnetic monopole. Since 2012, a dedicated Slow-Particle Filter has been implemented in the IceCube Neutrino Observatory for the detection of magnetic monopoles. Current limits set an upper bound for the monopole flux at $\Phi_{\mathrm{90}}\leq 10^{-17}$ to $10^{-18} \mathrm{cm}^{-2}\mathrm{s}^{-1}\mathrm{sr}^{-1}$ depending on the catalysis cross section for the proton decay. A detection of the monopole flux thus requires exceptional background rejection and signal efficiency. This is accomplished using machine learning methods. In this analysis, we use a multi-level boosted decision tree classifier. We present the strategy behind the background and signal simulation, the classification efficiency, and IceCube’s projected sensitivity for the detection of sub-relativistic magnetic monopoles.

Speaker: Jonas Häußler (RWTH Aachen University | IceCube Collaboration)

13:20 → 14:50 GA: IACT

13:20 Overcoming the physical limits of Cherenkov telescopes

Imaging with Cherenkov telescopes was a breakthrough for gamma ray astronomy. However, by pushing Cherenkov telescopes to ever higher precision and ever larger sizes our upcoming generation of telescopes has reached the intrinsic limits of imaging itself. Aberrations limit our field-of-view and the angular resolution in the gamma-ray sky. The square-cube-law escalates the costs to construct rigid structures for the optics of ever larger telescopes. A narrowing depth-of-field in larger telescopes prevents us from lowering the energy threshold for cosmic gamma rays as it blurs the images irrecoverably. While aberrations can be mitigated by more complex and costly optical surfaces, and while the square-cube-law can be mitigated by spending disproportionally more resources, the narrowing depth-of-field is a physical limitation of imaging and the telescope itself which can not be overcome by spending resources. We will show that all these limitations can be overcome by not only measuring the direction of a photon, as the telescope does it, but by additionally measuring the position where the same photon is reflected on the telescope's mirror. With a groundbreaking optics, our proposed Cherenkov plenoscope does exactly this without blocking or losing any light. The plenoscope can tolerate deformations and misalignments of its mirror and camera what postpones the square-cube-law and lowers the costs. The plenoscope can compensate aberrations of its mirror what widens its field-of-view. And the plenoscope turns the telescope's narrow depth-of-field into the perception of this depth giving the plenoscope intrinsic stereoscopic reconstruction power. Plenoptic perception has far reaching consequences for gamma- and cosmic-ray astronomy. We will present one possible consequence which is a Cherenkov plenoscope that aims for an energy threshold of one giga electronvolt for cosmic gamma rays. The plenoscope allows for the first time the high-resolution imaging of low energy gamma ray air showers using a huge (71m) mirror. For the first time we might be able to collect the more abundant low energetic gamma rays, for which the universe is still transparent up to high red shifts, in the large collecting areas of the atmospheric Cherenkov method. With astronomy pivoting towards the time domain, the Cherenkov plenoscope might become the next generation's timing explorer in the gamma ray sky to clock the emission from gravitational mergers, bursts, recurring novas, flaring jets, pulsars, and many more.

Speaker: Sebastian Achim Mueller (Max Planck Institute for Nuclear Physics)

13:35 Hadron Collider Measurements for IACT Background Modeling

Ground based gamma ray measurements with IACTs suffer from irreducible backgrounds from a specific type of cosmic-ray induced air showers. These air showers are characterized by a large electromagnetic component which is mostly due to highly energetic neutral pions produced in the primary interaction of cosmic rays with atmospheric nuclei. Current event generators that model these hadronic interactions show significant discrepancies in their predictions, especially for high energetic pion production, which translate into the dominant source of systematic uncertainties for gamma-ray analyses. In this talk, we identify regions of phase space in which current collider experiments, such as LHCf and RHICf, are sensitive to these processes. The corresponding measurements should lead to significant improvement of hadronic interaction modeling in general and reduce the systematic uncertainties for gamma-ray astronomy with IACTs.

Speaker: Clara Elisabeth Leitgeb (Humboldt University of Berlin (DE))

13:50 Stellar Intensity Interferometry observations at the Cherenkov Telescope Array Observatory with the Medium-Sized Telescopes

The current generation of Imaging Atmospheric Cherenkov Telescopes (IACTs: HESS, VERITAS and MAGIC) has led to a renaissance in the use of stellar intensity interferometry for sub-milliarcsecond optical astronomy. This technique, used over distances of O(100 m) between telescopes, enabled the measurement of stellar radii on the order of a few hundred micro-arcseconds with a ~10% resolution (assuming disk-like emission) for about 30 stars and binary systems. The new generation of IACTs, the Cherenkov Telescope Array Observatory (CTAO), is starting to follow this path. In particular, an SII observing system has been implemented in the camera of the first large-sized telescope at the CTAO North site, in conjunction with the MAGIC telescopes at La Palma (Spain).

The larger the number and extent of the baselines, the better the angular resolution of SII measurements for smaller and/or fainter stellar objects. Thus, the addition of the medium-sized telescopes (MSTs) to SII observations at the CTAO sites will improve angular resolution to a few percent for the stars already measured. In addition, a relative precision comparable to that of previous generation IACTs will be achieved for a few hundred stars. SII observations with CTAO will also allow limb and gravity darkening, stellar ellipticity, etc., to be measured with a precision unattainable with previous generation IACTs.

But the larger the extent of the baselines, the more difficult it is to combine the signals from telescopes up to a kilometer apart. Previous SII projects with IACTs and hardware from radio interferometry experiments provide the necessary technology to equip the NectarCAM camera of the MSTs with an SII observing system. Two technological solutions are investigated. One is a digital acquisition system integrating an improved WhiteRabbit node (IDROGEN), and the other is an analog acquisition system based on a vertical cavity surface emitting laser employed in the current-generation gamma-ray observatories.

In this contribution, we present the dedicated equipment for SII observations that is proposed for the NectarCAM. We also showcase the expected improvements in the constraints of disk-like and limb-darkened stellar extensions by including the MSTs in the CTAO proposed SII arrays. The addition of SII capabilities to CTAO promises to fully open a window left ajar by Hanbury-Brown and Twiss half a century ago.

Speaker: Quentin LUCE (Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay (France))

14:05 Bayesian approach to signal estimation in gamma-ray astronomy with Gammapy

A fundamental challenge for observations with Imaging Atmospheric Cherenkov Telescopes is the treatment of the dominant background of cosmic-ray initiated air showers. Traditional frequentist methods for signal estimation rely on gamma-hadron separation cuts to remove a large fraction of background events (reducing the efficiency of gamma-ray detection). In this work we adopt and extend a method known as Bayesian Analysis including Single-event Likelihoods (BASiL), in which these separation cuts are avoided by including into the likelihood function the probabilities of observed events originating from gamma or cosmic rays. With this approach, we retain 10 to 20% more signal throughout the analysis, particularly improving low signal-to-noise regimes and lowering the energy threshold. From the posterior probability of the source signal, credible intervals can be used to derive statistical uncertainties on flux points, while the computation of the Bayes factor allows the assessment of the probability of source detection. By adapting the open-source package Gammapy, we combine BASiL and the forward folding method to fit models and extract source spectra even from highly background-dominated data. This has potential applications to weak-source analyses or transient phenomena. We present results from simulated sources in the context of the H.E.S.S. telescopes, both in the 1-dimensional (data binned in energy) and a novel 3-dimensional analysis extension (data binned in energy and spatial coordinates), investigating how the method performs under distinct observation conditions and source characteristics.

Speaker: Matheus Genaro Dantas Xavier (Erlangen Centre for Astroparticle Physics (ECAP), Friedrich-Alexander-Universität Erlangen-Nürnberg)

14:20 First IACT Waveform Analysis Based on Deep Convolutional Neural Networks Using CTLearn

Imaging atmospheric Cherenkov telescopes (IACTs) detect extended air showers (EASs) generated when very-high-energy (VHE) gamma rays or cosmic rays interact with the Earth's atmosphere. Cherenkov photons produced during an EAS are captured by fast-imaging cameras, which record both the spatial and temporal development of the shower, along with calorimetric data. By analyzing these recordings, the properties of the original VHE particle—such as its type, energy, and direction of arrival—can be reconstructed through machine learning techniques. This contribution focuses on the Large-Sized Telescopes (LSTs) of the Cherenkov Telescope Array Observatory, a next-generation ground-based gamma-ray observatory. LSTs are responsible for reconstructing lower-energy gamma rays in the tens of GeV range. We explore a novel event reconstruction technique based on deep convolutional neural networks (CNNs) applied on calibrated and cleaned waveforms of the IACT camera pixels using CTLearn. Our approach explicitly incorporates the time development of the shower, enabling a more accurate reconstruction of the event. This method eliminates the need for charge integration or handcrafted feature extraction, allowing the model to directly learn from waveform data.

Speaker: Tjark Miener (Universite de Geneve (CH))

14:35 Classifying Waveform MAGIC Telescope Data Using Graph Neural Networks

Deep learning techniques have continued to evolve and find novel applications across scientific disciplines, and Graph Neural Networks (GNNs) have emerged as a high-performance architecture particularly suited for datasets with irregular topology. The MAGIC Telescope, comprising a pair of 17 m Imaging Atmospheric Cherenkov Telescopes (IACTs) located at Roque de Los Muchachos Observatory in La Palma, Spain, is designed to detect gamma rays from around 50 GeV to over 50 TeV. IACT arrays rely on a multilayered pipeline in which each particle registered by the detectors creates a stereo signal which must be calibrated, converted to an image, cleaned, parameterized, and ultimately labeled by several machine learning algorithms. In recent years, Convolutional Neural Networks (CNNs) have shown great promise in performing both classification and regression tasks, demonstrating a comparable performance on calibrated IACT images. In contrast, this study leverages raw data, consisting of a 30 ns waveform signal in each pixel and covering the entire camera. Due to the unconventional geometry of the MAGIC cameras and uneven time-slicing across pixels, we represent raw-level MAGIC data as a point cloud graph and employ GNNs for the classification algorithm for the first time in an IACT. Our preliminary trials indicate that GNNs not only represent a robust method for analyzing raw MAGIC data, but also show potential for fast on-site data reduction and even direct telescope triggering.

Speaker: Jarred Green

13:20 → 14:50 GA: microquasars & binaries

13:20 Resolved gamma-ray emission around the microquasar V4641 Sgr

Microquasars have been shown to be capable to accelerate particles to energies well above 100~TeV. The reported presence of hadronic particles in their jets makes them one of the most convincing PeVatron candidates. Their proximity to Earth allows detailed studies of their morphology, providing unique laboratories for the study of particle acceleration in jets. The LHAASO Observatory has reported the detection of TeV emission from 5 microquasar systems, and in particular, photons of up to 800 TeV from the microquasar V4641 Sgr. In this contribution we present the result of several years of H.E.S.S. observation of this source. While it is clear that V4641 Sgr is one of the most powerful and efficient particle accelerators in our Galaxy, many questions remain around the system. It is unclear whether the emission is leptonic or hadronic, how the extended gamma-ray emission relates to the reported low-inclination jets and where exactly in the system does particle acceleration take place. With the increased angular resolution of H.E.S.S. we are able to study in detail the spectral and morphological properties of the TeV emission around this intriguing system and tackle these questions. Understanding how particles are accelerated in the jets of V4641 Sgr would not only provide valuable insights to the study of particle acceleration in jets in general but also constrain the relative contribution of microquasars as a class to the observed cosmic ray spectrum.

Speaker: Laura Olivera Nieto (Max-Planck Institut für Kernphysik)

13:35 Observation of Cygnus X-1 and Cygnus X-3 with LHAASO

The detection of very high-energy (VHE) and ultra-high-energy (UHE) emissions associated with micro-quasars has unveiled a new class of powerful particle accelerators. The particles are suggested to be accelerated within their jets or surrounding environments. Cygnus X-1 and Cygnus X-3 are two prominent micro-quasars located in the Cygnus region. Significant efforts have been dedicated to searching for gamma-ray emissions from these systems. In this presentation, I will provide a brief overview of the recent findings from the Large High Altitude Air Shower Observatory (LHAASO) regarding these two micro-quasars.

Speaker: Cong Li (The Institute of High Energy Physics of the Chinese Academy of Sciences)

13:50 Multimessenger emission from the microquasar V4641 Sgr

Very high-energy gamma-ray emission from the microquasar V4641 Sgr with energy up to beyond 100 TeV has been recently detected with the H.E.S.S., HAWC, and LHASSO observatories. The gamma-ray emission reveals a puzzling 200-parsec-long structure significantly misaligned with its radio jet. We propose that this gamma-ray structure is produced by high-energy cosmic-ray particles escaping from the microquasar along ordered field lines of the Galactic Magnetic Field and interacting with the interstellar medium. If the gamma-ray emission is produced by interactions of high-energy cosmic ray nuclei, the system is detectable by future multi-km3 neutrino detectors. Finally, we argue that gamma-ray observations of jet-like features adjacent to high-energy sources in the Milky Way provide a new method to measure the regular and turbulent components of the Galactic magnetic field at different locations in the Milky Way.

Speaker: Prof. Foteini Oikonomou (NTNU)

14:05 Exploring the Intriguing Ultra-High-Energy Microquasar V4641 Sgr with HAWC

Microquasars are powerful cosmic particle accelerators within our galaxy, known for emitting gamma rays at energies beyond the multi-teraelectronvolt (TeV) range. Whether they can accelerate particles to PeV energies and qualify as PeVatrons remains an open question, with SS 433 being the only confirmed TeV-emitting microquasar. The High-Altitude Water Cherenkov (HAWC) Observatory has first detected ultra-high-energy (UHE) gamma rays from another microquasar, V4641 Sagittarii (V4641 Sgr), revealing previously unknown particle acceleration processes. Known for its rapid outbursts and relativistic jets, V4641 Sgr provides a key laboratory to study particle acceleration, jet formation, and black hole accretion. The detection of UHE gamma-ray emission by HAWC offers valuable insights into the extreme environment near the black hole, supporting theories of jet-driven particle acceleration and highlighting the complex interactions between the jets and surrounding matter. These findings not only enhance our understanding of microquasars but also shed light on their role in cosmic-ray production and accelerations, providing a fresh perspective on high-energy astrophysical processes.

Speaker: Sabrina Casanova (IFJ PAN Krakow)

14:20 Microquasars as the main Galactic PeVatrons

Recently, LHAASO published its measurement of the Galactic diffuse gamma-ray emission in the $\rm{TeV}-\rm{PeV}$ range, which seemed to be $2$ to $3$ times higher than theoretical expectations. To explain the apparent discrepancy, an important contribution from a population of unresolved pulsars or important spatial variations in the cosmic-ray density have been proposed. We show through a robust data-driven approach based on the ATNF and LHAASO catalogs that the contribution of unresolved pulsars can hardly reach $50\%$ around $30\,\rm{TeV}$ and is smaller than $25\%$ of the flux of LHAASO at $100\,\rm{TeV}$ [1]. On the other hand, we find that forecasting a small number of $\sim10$ microquasars acting as powerful PeVatrons [2] leads to a self-consistent description of our Galaxy at very-high-energy. In this scenario, the cosmic-ray spectrum and the LHAASO data in the $\rm{TeV}-\rm{PeV}$ range are well-fitted owing to the important fluctuations in the cosmic-ray density induced by the small number of sources, while the number of detectable microquasars above $100\,\rm{TeV}$ remains consistent with the latest LHAASO detections. We conclude that our findings support the picture in which the high-energy end of the Galactic cosmic-ray spectrum is dominantly, if not entirely, contributed by a small subset of very powerful microquasars.

[1] S. Kaci, G. Giacinti, D. Semikoz, ApJ. Lett. 975, L6 (2024).
[2] S. Kaci, G. Giacinti, J-S. Wang (2025). To be submitted very soon.

Speaker: Samy Kaci (Tsung-Dao Lee Institute, Shanghai Jiao Tong University)

14:35 Results of the historical observations of the microquasar Cygnus X-3 with the MAGIC telescopes.

Cygnus X-3 is a microquasar consisting of a compact object of unknown nature and a Wolf-Rayet star, which orbit each other with a very short period of 4.8 hours. The compact object launches powerful jets that are an excellent site for particle acceleration up to relativistic energies. The presence of these relativistic particles, combined with the proximity to the star and its high luminosity, make the conditions in the source very favorable for inverse Compton scattering of stellar photons by the jet electrons, resulting in gamma-ray emission. Cygnus X-3 has been detected in a broad frequency range, from radio to gamma rays above 100 MeV, although it has never been confirmed as a very-high-energy (VHE, above 100 GeV) gamma-ray emitter. Studies of microquasars in gamma rays have recently become a hot topic in the community after the LHAASO detection of four microquasars above 100 TeV, establishing these sources as potential contributors to the Galactic cosmic-ray spectrum at energies above the PeV.
Due to the scientific interest of the source, the MAGIC telescopes have observed Cygnus X-3 in the VHE band since they became operational. In this contribution, we will present a long-term analysis of 130 h collected by MAGIC between 2013 and 2024. This represents the largest available dataset (in both exposure and time coverage) at VHE to date, resulting in the strongest VHE upper limits of the source between 100 GeV and a few TeV. Both the temporal and spectral constraints of Cygnus X-3 during this 11-year period will be interpreted within the multi-wavelength context, providing meaningful constraints to the source properties based on its (lack of) emission in gamma rays at different energies.

Speaker: Luis Barrios Jiménez (IAC, ULL)

13:20 → 14:50 GWMS

13:20 THE DIFFUSE HIGH ENERGY NON-AGN NEUTRINO EMISSION

The diffuse astrophysical neutrino flux measured in the very high energy range introduced unresolved issues about the origin of these events and underlined as a viable solution the multi-component scenario. Recent studies show that galaxies with high star formation rate (above teens Mo/year) can be responsible of a seizable fraction of the observed astrophysical flux. Despite their low luminosity, they can be considered as guaranteed “factories”of high energy neutrinos, being “reservoirs”of accelerated cosmic rays and hosting a high density target gas in the central region. On the other hand, in the same range of energies, recent measurements of IceCube and Antares telescopes set the contribution correlated with the diffuse Galactic emission. The Milky Wayis a prominent astrophysical lab to correlate the high-energy diffuse emission with the physics of cosmic-ray injection and propagation as well as with the measured molecular gas distribution. In this contribution we describe in details these two diffuse astrophysical components and we show that the associated non-AGN diffuse neutrino flux can represent a sizeable portion of the flux observed by high-energy neutrino telescopes.

Speaker: Antonio Marinelli (Università di Napoli, Federico II)

13:35 Constraints on the ultra-high-energy Galactic gamma-ray emission from neutrino data

We have shown in [1] that at ultra-high-energy (UHE) the Galactic diffuse gamma-ray emission is very patchy, due to the short residence time of cosmic rays in the Galaxy and the scarcity of Galactic PeVatrons. However, such a patchiness remains hard to firmly attribute to the diffuse component of the Galactic emission due to the presence of a population of unresolved pulsars whose contribution remains poorly constrained. Moreover, the same population of unresolved pulsars is also suspected of being responsible for an increase (up to a factor $3$) of the diffuse flux measured by LHAASO, making the interpretation of gamma-ray observations very challenging. However, neutrino observations, which exclusively track interactions of hadronic cosmic rays, can provide reliable answers to these questions. In particular, using our code incorporating stochastic distributions of cosmic-ray sources [1], we constrain the hadronic contribution to the diffuse gamma-ray background of LHAASO based on a fit of the IceCube neutrino data in a self-consistent way. While the diffuse gamma-ray background has a leptonic contribution that may reach a few tens of percent at few tens of $\rm{TeV}$, above $\sim100\,\rm{TeV}$ we find that it is largely dominated by its hadronic component with a minimal leptonic contribution [2]. Moreover, we show how future $\sim10\,\rm{km}^3$ neutrino observatories can provide unequivocal proofs of the patchy morphology of the UHE diffuse gamma-ray background and help to constrain the number of Galactic hadronic PeVatrons, their number, and the propagation of cosmic-rays around them.

[1] S. Kaci, G. Giacinti, JCAP 01, 049 (2025).
[2] S. Kaci, G. Giacinti, In prep. (2025).

Speaker: Samy Kaci (Tsung-Dao Lee Institute, Shanghai Jiao Tong University)

13:50 Search for Neutrinos from the Galactic 4FGL Sources with the Pion-bump Signature with IceCube

The IceCube Neutrino Observatory, located at the South Pole, covers a cubic kilometer of Antarctic ice, designed to detect astrophysical neutrinos in the TeV-PeV energy range. While IceCube has recently identified a diffuse flux of neutrinos originating from the Galactic Plane, specific sources of astrophysical neutrinos within the Milky Way remain elusive. Hadronic gamma-rays, produced through the decay of neutral pions, display a characteristic “pion bump” or “spectral break” around 200 MeV. Recent studies by the Fermi-LAT Collaboration highlight 56 sources from the 4FGL Catalog exhibiting a spectral break in the MeV energy range. Detecting astrophysical neutrinos from these sources would provide compelling evidence for cosmic-ray acceleration in their vicinity. In this analysis, we search for astrophysical neutrino emission from 56 sources showing characteristics of a pion bump using 13 years of IceCube data. Our findings could enhance our understanding of potential cosmic-ray acceleration sites in the galaxy.

Speaker: Alejandra Maria Granados Hernandez (Michigan State University)

14:05 IceCube population constraints on neutrino emission by Fermi-LAT detected active galactic nuclei

Gamma-ray bright active galactic nuclei (AGN) have been one of the most promising source classes of high-energy astrophysical neutrinos detected by IceCube. The first evidence of an IceCube point source was a blazar detected by the Fermi Large Area Telescope (LAT), TXS 0506+056. Previous analyses have ruled out GeV-bright blazars as the predominant contributor to the high-energy astrophysical neutrino flux under simple assumptions about the relationship between the fluxes of gamma rays and neutrinos. We present results from a more general and more sensitive search for correlation between neutrinos and GeV-selected AGN using improvements in the IceCube statistical methods and 13 years of data. We detect no correlation, and set stringent constraints on neutrino emission by populations of GeV-detected AGN. These include constraints on the neutrino emission from subclasses of GeV-detected AGN, including BL Lacs, flat-spectrum radio quasars and non-blazar AGN, using stacking analyses testing a variety of hypothesized relationships between neutrino and gamma-ray flux. We also present results from an analysis that is sensitive to a wider range of relationships between the gamma-ray and neutrino signal.

Speaker: SAMUEL HORI

14:20 Mergers of binary-neutron-stars as production sites of high-energy neutrinos

The merging of binary-neutron-stars (BNS) could host regions where high-energy neutrino production is possible. In this talk, we consider a population of BNS mergers that accelerate cosmic-ray (CR) particles to energies of the ankle of the CR measured spectrum. Taking inspiration by the event GW170817, detected in gravitational waves and in several wavelengths, we model the CR interactions and the consequent neutrino production in the thermal and non-thermal photon environment. The dependence of the target photons fields as a function of the time after the merger is also taken into account. The expected neutrino and CR fluxes at Earth are compared to experimental data, and an estimate of the corresponding diffuse gamma-ray background is provided. The source-propagation model here proposed shows the requested conditions in terms of source properties to satisfy both the measured neutrino and CR flux, and allows to constraining the fraction of accelerated baryons in the source site given the BNS merger rate per volume.

Speaker: Denise Boncioli

14:35 Joint Detection Prospects of Binary Neutron Star Mergers using CTA - Gravitational-Wave Detectors and high energy neutrino emission scenarios

Binary neutron star (BNS) mergers are the source of most ultrahigh-energy cosmic rays, making them key astrophysical events for multi-messenger studies. The joint detection of gravitational waves (GW170817 by GW detectors) along with spatially coincident short gamma-ray burst (sGRB) GRB170817A has established a clear connection between BNS mergers and sGRBs. In our recent study, we investigate the joint detection probabilities of BNS mergers by GW detectors, specifically for observing run O5 of the LIGO/Virgo/Kagra (LVK) network, with the synergy of upcoming ground-based very-high-energy (VHE) gamma-ray instrument, the Cherenkov Telescope Array (CTA) within 300~Mpc BNS horizon. Assuming the Gaussian structured jet profile and ignoring large sky localization constraints of GW detectors, we estimated VHE afterglow detection probability by CTA. We have comprehensively explored the multi-dimensional afterglow parameter space to identify conditions favourable for detecting GRB afterglow synchrotron self-Compton emission by CTA. The estimated joint detection event rate varies significantly with afterglow parameter distributions, ranging from 0.003 to 0.5 per year. We also estimate the high-energy neutrino flux from afterglow emissions of those events jointly detected by CTA and LIGO. Further, we calculate the rate of neutrino detection from individual sGRBs at the luminosity distance and the total kinetic energy of the blast wave, which is most probable for joint detection. Finally, we determine the detection upper limit for neutrino flux for the currently operating neutrino detectors.

Speaker: Ms Tanima Mondal (IIT Kharagpur, India)

13:20 → 14:50 NU: atmospheric interpretations & MM studies

13:20 Selecting Hadronic Supernova Remnants for Targeted Galactic Neutrino Searches

Neutrinos provide unambiguous evidence of cosmic-ray (CR) acceleration in supernova remnants (SNRs), as they are produced exclusively in hadronic interactions. Detecting neutrinos from a SNR would offer direct confirmation of CR proton interactions and energy distributions. In this work, we conduct a comprehensive survey of Galactic SNRs to identify the most promising hadronic candidates. For this subset, we model the expected neutrino spectra and compile a prioritized source list for a future IceCube stacking analysis. Excluding leptonic-dominated SNRs from IceCube analyses is crucial for improving the signal-to-noise ratio and has the potential to enable the first detection of Galactic SNRs in neutrinos.

Speaker: Emily Simon

13:35 Investigating the Origin of the Neutrino Excess in the Cygnus Bubble Core

The Large High Altitude Air Shower Observatory (LHAASO) observed a giant $\gamma$-ray bubble from the direction of the Galactic star-forming region Cygnus-X. The morphology and the energy spectrum of the bubble suggest that these $\gamma$-rays are correlated to the interactions between cosmic rays and gas clumps, indicating the expectation of an extended neutrino counterpart. Using public IceCube muon-track data, we found hints of neutrino signals exceeding both the atmospheric background and isotropic astrophysical neutrinos within the bubble, with a post-trial significance of $1.7\sigma$. Interestingly, within $0.7^{\circ}$ of the bubble center, the neutrino signals show a notable excess over expectations, even if all $\gamma$-rays of Cygnus bubble are of hadronic origin. To explain observations, we proposed that neutrinos primarily originate from a central $\gamma$-ray hidden source, with the microquasar Cygnus X-3 dominating the excess. This finding hints at microquasars as potential sources of high-energy neutrinos. Next-generation neutrino telescopes at the $10\,{\rm km^3}$ scale could have the capability to identify these sources.

Speaker: Tian-Qi Huang

13:50 Multimessanger study of the Cygnus region: the local hadronic component and the Galactic cosmic-rays sea.

The Cygnus-X star forming complex is a very active and interesting region of the Galaxy with massive molecular clouds and candidate PeVatron sources, such as the young massive stellar association Cygnus OB2.
Indeed, a gamma-ray emission from this region has been initially observed by Milagro, and subsequently by Fermi-LAT (HE), Argo (VHE), HAWC (VHE) e LHAASO (VHE-UHE). This emission was only hinted in neutrinos, so far.
Motivated by these recent claims, we investigate a possible neutrino excess from the Cygnus-X region by analyzing the IceCube public track-like data sample which comprise 10 years (2008-2018) of data taking.
We model both gamma-ray and neutrino emission assuming a pure hadronic scenario, where CRs are accelerated by Cygnus OB2. When performing a multi-messanger fit, we also account for the effect of particle propagation in the environment surrounding the association. Finally, when comparing to the neutrino data, we model the emission related to the diffuse cosmic-ray sea in this region by using the KRA-gamma model.

Speaker: Riccardo Maria Bozza (INFN Napoli)

14:05 Neutrinos as a new tracer of the gas distribution in the Milky Way Centre

The centre of the Milky Way hosts the most massive and dense clouds of molecular hydrogen gas in our Galaxy. The inferred star formation efficiency at the Galactic Centre is however surprisingly low given the large gas reservoir. Yet the huge uncertainty in the measurement makes the comparison between observations and theories difficult. Measurements of the gas density based on different mass tracers yield inconsistent results, even when using conventional probes such as CS and dust. We propose using neutrinos as an alternative, independent gas tracer to resolve this ambiguity. Neutrinos are produced when cosmic rays interact with the cloud gas, with their surface brightness directly proportional to the cloud's density integrated along the line of sight. In this talk, we quantify the impact of future neutrino data from the next generation of telescopes—KM3NeT, Baikal-GVD, and P-ONE—which offer angular resolutions better than a tenth of a degree for detecting muon neutrinos from the Galactic Centre. We show how neutrinos will improve the measurement on the gas density, allowing for more robust test of star formation theories.

Speaker: Paul Chong Wa Lai (University College London)

14:20 Interacting Supernova Remnants as Sources of High-Energy Gamma Rays and Neutrinos

Multiwavelength observations indicate that supernova remnant (SNR) shocks are sites of effective particle acceleration, playing a crucial role in the origin of cosmic rays. When supernovae (SNe) explode in complex environments containing dense structures—such as molecular clouds, clumps, or stellar winds—these dynamics can significantly enhance hadronic interaction processes, leading to distinctive modifications in the gamma-ray spectrum and the production of high-energy neutrinos. The detection of such neutrinos would provide direct evidence of cosmic-ray interactions with ambient matter, offering crucial insights into particle acceleration in astrophysical shocks.
Hydrodynamic (HD) and magnetohydrodynamic (MHD) models serve as powerful tools to investigate the impact of environmental conditions on the hadronic gamma-ray emission and to predict the associated neutrino flux. In this work, we present HD/MHD models for selected SNRs considered promising neutrino source candidates. We derive their expected hadronic gamma-ray and neutrino emissions and assess their detectability with the next-generation KM3NeT neutrino telescope.

Speaker: Sabina Ustamujic

14:35 Multi-messenger emission from choked jets in collapsars

The death of massive stars is accompanied by the formation of central and accreting compact objects and the subsequent launch of relativistic jets. However, not all jets successfully drill their way out of the stellar envelope, which would result in gamma-ray emission. Unsuccessful jets, also known as choked jets, might still produce radiation at lower frequencies by dissipating the jet energy into a pressurized cocoon, which expands within the stellar envelope and eventually breaks out as a mildly relativistic outflow. In order to investigate the radiation output of choked jets, we perform radiative relativistic non-resistive MHD simulations of jets launched into collapsars and derive in post-processing analysis the secondary emission by accelerated particles at shocks, including multi-wavelength and neutrino spectra. Our results are shown for different configurations of the system.

Speaker: Matteo Pais (INAF - Osservatorio astronomico di Padova (OAPD))

13:20 → 14:50 NU: highlights & analysis

13:20 Search for UHE neutrinos from GRBs with the Pierre Auger Observatory

We report on the search for ultra-high-energy neutrinos from the prompt emission of gamma-ray bursts (GRBs) using Surface Detector (SD) data from Phase One of the Pierre Auger Observatory (2004–2021). A total of 570 GRBs occur within the most neutrino-sensitive field of view of the SD, considering both Earth-skimming and downward-going detection channels. For this purpose, GRB neutrino emission has been modeled using the numerical software NeuCosmA, incorporating gamma-ray measurements and inferred parameters such as the jet Lorentz factor and the minimum variability time scale. No neutrino candidates were found, and upper limits were obtained by stacking the individual GRB neutrino fluences. These limits are complementary to those of IceCube and ANTARES and provide the strongest constraints on prompt GRB neutrino fluence above $10^{18}$ eV. Additionally, limits on GRB luminosity in alternative models of neutrino production have been derived using Auger data.

Speaker: YAGO LEMA CAPEANS

13:35 High-Fidelity Simulations of the Full Askaryan Radio Array and its Sensitivity to Ultra-High Energy Neutrinos

The Askaryan Radio Array (ARA) is a five-station, in-ice radio detector located at the South Pole searching for particle cascades from cosmogenic and astrophysical neutrinos with >1e17 eV of energy. Cascades in this energy regime emit radio-wavelength Askaryan radiation that can be observed by one or more ARA stations. With the recent Km3Net observation of an approximately 2e17 eV neutrino, there is renewed, urgent interest in further unlocking the ultra-high energy (UHE) neutrino sky. This work delivers updated calculations of ARA’s array-wide effective volume, sensitivity, and expected event rates for UHE neutrino-induced cascades. Notably, results now account for the contributions of secondary particles from neutrino interactions (such as muon tracks) and multi-station detections within a detailed detector simulation framework. Previous work has shown these secondary interactions and multi-station coincidences compose 25% and 8% of the detector’s effective area, respectively. We intend to extend these results towards a novel analysis estimating the degree to which secondary cascades and multi-station observations are detectable in a real neutrino search. This will inform future UHE neutrino searches as it will characterize the feasibility of detecting such events.

Speaker: Abby Bishop (University of Wisconsin - Madison)

13:50 Construction, commissioning and operation of the Radio Neutrino Observatory in Greenland (RNO-G)

The Radio Neutrino Observatory Greenland (RNO-G) is searching for Askaryan radio signals from ultra-high-energy neutrinos ($E \ge 100\,$PeV) interacting in ice. RNO-G is currently under construction near the apex of the Greenland ice sheet with 8 stations already operational and collecting science data. The constructed observatory will consist of 35 autonomously operating stations deployed over an area of about 50$\,$km$^2$. Its projected sensitivity will allow to test several models of astrophysical and cosmogenic neutrinos with the potential to detect neutrinos above 100$\,$PeV.

Each RNO-G station features 24 radio antennas installed in 3 100$\,$m-deep-boreholes with a diameter of 30$\,$cm and shallow trenches beneath the surface. The stations are powered by solar and wind energy and are each equipped with low-power electronics for data readout and wireless communication to a central server at the nearby NFS-operated Summit Station. RNO-G is the first experiment probing the large-scale in-ice radio detection with tens of stations and hundreds of channels over a large area. It is designed to withstand the harsh conditions of an Arctic environment, with scalability in mind. As such, its construction and operation provides invaluable insights for the development and construction of the planned 500$\,$km$^2$ radio detector of the IceCube-Gen2 facility.

In this contribution, I will give an overview of recent deployment activities, the operation of the 8 deployed stations and discuss the hardware performance over the past 4 years.

Speaker: Felix Schlüter

14:05 Status of RNO-G's First Neutrino Search

The Radio Neutrino Observatory in Greenland (RNO-G) is located at Summit Station and is designed to detect Askaryan emission from ultra-high energy (UHE) neutrinos above 100 PeV. The detector is proposed to have 35 stations of which 8 have been built so far. Each station is made up of antennas that are buried at a depth of 100 meters with the purpose of triggering on and reconstructing neutrino-like signals. The partially completed detector has been collecting data since 2021 and this data is being used for RNO-G’s first neutrino search. This talk will outline progress towards this search, such as the data processing pipeline, analysis variables, initial reconstructions, and background/signal separation. We will also present a projected sensitivity.

Speaker: Brian Clark (University of Maryland)

14:20 Search for neutrino emission from Microquasars with KM3NeT/ORCA detector

Microquasars are galactic binary systems that present non-thermal acceleration mechanisms. These systems are thought to consist of a compact object and a companion star, leading to the formation of an accretion disk similar to those in quasars.
The composition of microquasar jets remains uncertain. However, neutrino production becomes a possible outcome if protons are present in situ. Detecting neutrinos from microquasars would not only provide insights into their jet composition but also establish them as potential sources of galactic cosmic rays.

KM3NeT/ORCA, a neutrino telescope located at the bottom of the Mediterranean Sea near La Seyne-sur-Mer, France, is capable of detecting such neutrinos in the GeV-multiTeV energy range. Data collection began in early 2020 and will continue throughout its construction until it reaches full detection capability.

This study presents a search for neutrinos emitted by microquasars using the full KM3NeT/ORCA dataset, leveraging multiwavelength observations. The analysis focuses on outburst periods to minimize atmospheric background, employing machine-learning techniques to filter out likely atmospheric events. Finally, the results are compared with theoretical expected fluxes and upper limits given by other neutrino experiments.

Speaker: Francesco Magnani

14:35 Prospects of neutrino observations of the Central Molecular Zone and Cygnus cocoon with KM3NeT/ARCA

In this contribution, a search for neutrino emission from the Central
Molecular Zone (CMZ) and the Cygnus Cocoon is presented exploiting
KM3NeT/ARCA capabilities. The CMZ extends for a few hundred par-
secs around the Galactic center, containing the massive molecular clouds
Sgr A, Sgr B, and Sgr C. The Cygnus Cocoon is a massive star-forming
region of a few hundred parsecs in the constellation of Cygnus. It con-
tains regions with high gas densities and a rich stellar population. The
high energy emission from these regions is expected to be dominated by
the interactions of cosmic-rays with the molecular gas, which translate
into gamma-ray and neutrinos production. Here we present a search for
neutrino emission from these two regions. We explored the sensitivities of
the current KM3NeT/ARCA geometry as well as the case of the complete
future detector.

Speaker: Marouane Benhassi (University of Campania Luigi Vanvitelli (Italy))

14:50 → 15:19 Coffee

15:19 → 16:50 CRI: spectrum

15:19 Advances in reconstructing the cosmic-ray energy spectrum with IceTop

The IceTop array at the surface of the IceCube Neutrino Observatory measures extensive air showers produced by cosmic-ray particles with energies from PeV up to EeV, covering the transition region from galactic to extragalactic sources. This contribution presents significant improvements that will enhance the measurement of the IceTop energy spectrum. (I) To analyze more than a decade of data with increasing snow overburdens on the detector, an improved method to handle the time-dependent attenuation of the detector signals was developed. (II) New analysis cuts have been developed to increase the measured event rate while improving the reconstruction quality. (III) A new reconstruction that separately fits the electromagnetic and muonic components and includes information from the in-ice detector to reconstruct the geometry of an air shower allows for the reconstruction of more air showers than was previously possible: those landing outside of IceTop’s boundaries up to distances of 2300m and zenith angles up to 60°. These improvements will significantly increase the event statistics and extend the IceTop spectrum towards higher energies.

Speaker: Lilly Pyras (University of Utah)

15:34 The Cosmic Ray Event Spectrum in the Knee Region measured by the NICHE Array at Telescope Array

The NICHE array at Telescope Array is a non-imaging Cherenkov light detector situated close to the Telescope Array Middle Drum fluorescence detector site. It has been operating since September 2017. Data collected between June 2020 and July 2024 has been analyzed and we will present the energy spectrum of the cosmic rays observed. The threshold energy of the detector is about 1 PeV and the data collected gives significant statistics up to about 100 PeV. The energy reconstruction used in this analysis uses the CHASM model, a model which incorporates extensive air shower universality and Cherenkov photon production.

Speaker: Douglas Bergman (University of Utah)

15:49 Highlights of LHAASO Cosmic Ray Energy Spectrum and Composition Measurements

The Large High-Altitude Air Shower Observatory (LHAASO) is a hybrid detector experiment, including one square kilometer array of scintillator detectors and muon detectors, a 78,000 square meter water Cherenkov detector array and 18 wide field of view Cherenkov telescopes. This multi-parameter observation of air showers enables LHAASO to measure the energy spectrum and composition of individual cosmic ray elements with high resolution, providing a unique opportunity to explore the origin, acceleration, and propagation of high-energy cosmic rays. In this presentation, we will focus on the main results regarding the energy spectra of protons, helium, the combined spectrum of proton and helium, and the all-particle spectrum in the knee region as accurately measured by LHAASO.

Speaker: Shoushan Zhang

16:04 Measurement of All-Particle Energy Spectrum and Mean Logarithmic Mass of Cosmic Rays until hundreds of PeV

The Large High Altitude Air Shower Observatory (LHAASO) provides unprecedented capabilities for measuring cosmic-ray (CR) properties in the high energy regime. The LHAASO experiment has achieved unprecedented precision in measuring the cosmic ray all-particle energy spectrum and its mean logarithmic mass in the "knee" region. As statistics accumulate, it becomes feasible to accurately assess the cosmic ray all-particle energy spectrum and mean logarithmic mass at energies reaching hundreds of PeV. It is the transition region between the Galactic and extragalactic cosmic rays as proposed by most theoretical models. This study focuses on the cosmic ray all-particle energy spectrum up to hundreds of PeV, utilizing inclined incidence cases to measure cosmic ray energies at the maximum of atmospheric showers, ensuring high energy reconstruction precision. By optimizing the shower core position and zenith angle range, we enhance the cosmic ray observation aperture and improve the statistical yield. Combining information from the electromagnetic particle detectors and muon detectors of the LHAASO experiment, we develop an energy reconstruction method that is independent of the cosmic ray composition, thus eliminating the composition dependence on the energy spectrum and achieving high-precision cosmic ray energy spectrum measurements. Moreover, we accurately measure the mean logarithmic mass distribution of cosmic rays using the muon contents from air showers. Preliminary findings indicate “second knee” in the energy spectrum at around 100 PeV, and the mean logarithmic mass exhibits a gradual increase with energy, suggesting a transition toward heavier nuclear dominance across hundreds of PeV.

Speaker: Hengying Zhang (Yunnan University)

16:19 Highlights from the GRAPES-3 Experiment on Galactic Cosmic Ray Measurements

The GRAPES-3 experiment, located in Ooty, India (11.0^{o}N, 76.7^{o}E, 2200 m a.s.l.), uses a dense array of 400 plastic scintillator detectors and a 560 m^{2} tracking muon detector to measure all charged particles and the muonic components of cosmic ray showers, respectively. The experiment has measured the cosmic ray proton spectrum in the energy range of 50 TeV to 1.3 PeV, and the relative composition of proton was determined using muon multiplicity distributions. A spectral hardening was observed beyond 166 TeV, challenging the simple power-law description extending to the knee energy. Machine learning techniques are being explored to extract composition for other elements using composition sensitive parameters such as multiplicity distributions, shower age and other less discriminating parameters. Various high energy hadronic interaction models existing in the framework of CORSIKA including QGSJET-II-04, SIBYLL 2.3d, EPOS-LHC were studied including muon multiplicity distributions and lateral distributions and compared with the observed data. Furthermore, two significant small-scale anisotropic structures in the cosmic ray arrival distribution were detected at a median energy of 16 TeV, consistent with results from the HAWC and ARGO-YBJ experiments. With the same data set, large-scale anisotropy has been observed including dipolar structures with an iterative maximum likelihood method with a statistical significance exceeding 10 standard deviations. A second muon detector of 560 m^{2} area is in the advanced stage of its construction with 40% of modules are operational. The expanded muon detector will enhance the sensitivity for detection of gamma ray sources. This presentation will highlight these findings, along with updates on the status of the detector upgrades and future plans.

Speaker: Pravata Kumar Mohanty (Tata Institute of Fundamental Research)

16:34 Measurement of the Iron Spectrum with the MAGIC Telescopes

Iron cosmic rays represent the most abundant heavy nuclei at energies above 1 TeV, with their production thought to be primarily originated by astrophysical sources. Therefore, measuring the iron spectrum provides crucial insights into the origin, acceleration, and propagation mechanisms of cosmic rays. Recent results from space-based detectors have revealed unexpected energy dependences in the GeV-TeV range, but these measurements are limited by low statistics at higher energies. At energies above a few TeV, ground-based detectors, such as the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes, become more effective due to their large collection areas, enabling them to extend and complement the capabilities of space-borne instruments. In this work, we apply the so-called direct Cherenkov technique with MAGIC to identify iron-induced air showers and distinguish them from those produced by lighter cosmic-ray species. By using this technique, which accounts for the radiation emitted by charged particles before the cascade develops in the atmosphere, we are able to measure the energy spectrum of cosmic-ray iron nuclei above 10 TeV.

Speaker: Miguel Molero Gonzalez (Institute of Astrophysics of the Canary Islands (ES))

15:19 → 16:50 GA: microquasars & binaries

15:19 Study on Gamma-ray binaries with the LHAASO WCDA data

The study of gamma-ray binaries using LHAASO data provides crucial insights into high-energy astrophysics. These binaries, consisting of a massive star and a compact object, emit radiation primarily in the MeV to TeV range. LHAASO’s sensitivity enables detailed observations of key sources, including HESS J0632+057, PSR J2032+4127, GRS 1915+105, SS 433 (w1 & e1), and LS I +61 303, each exhibiting unique emission characteristics, periodic variability, and orbital modulations. SS 433, a micro quasar, provides a valuable case for studying relativistic jets, while HESS J0632+057’s wind-wind interactions highlight its eccentric orbit. PSR J2032+4127 and GRS 1915+105 contribute to understanding pulsar-driven and accretion-powered emissions, while LS I +61 303 reveal complex particle acceleration mechanisms. LHAASO’s WCDA and KM2A detectors provide high-significance detections of these sources, enabling precise spectral and temporal monitoring to enhance models of high-energy emissions in extreme astrophysical environments.

Speaker: Ms MARIAM HASAN (IHEP)

15:34 Deep observation of the gamma-ray binary LS 5039 with H.E.S.S.

LS 5039 is a High Mass X-ray Binary (HMXRB) comprising a compact object in an eccentric 3.9 day orbit around a massive O6.5V star. It is one of the most studied object in the field. A first HESS publication in 2004 established multi-TeV emission from the system (first ever TeV binary system). A second publication in 2006 , based on a deeper data set of ∼ 70h of observation, established the TeV orbital variability of the source. The period was measured to 3.9078 ± 0.0015 days, compatible with the ephemeris value of 3.90603 ± 0.00017 days, and spectral variability attributed to phase-dependent absorption by pair creation on the stellar photon field was reported.

Since 2006, a rather large amount of data was collected by H.E.S.S. with varying offset, in particular in the framework of the HESS Galactic Plane Survey, and for various neighboring sources. The available archival data set of ∼ 200 live hours and the improved analysis techniques developed since the early days of H.E.S.S. allows revisiting the source with unprecedented accuracy. With more than 5000 collected gamma-ray, detailed measurement of the spectral variability in bins of width of 0.1 in phase are now possible.

Detailed results on the orbital variability of LS 5039 and its interpretation will be presented at the conference.

Speaker: Dr Mathieu JACOBE DE NAUROIS (Laboratoire Leprince Ringuet IN2P3/CNRS - Ecole Polytechnique)

15:49 Searching for common emission mechanisms in seventeen years of VERITAS, Fermi-LAT, and Swift-XRT observations of LS I+61 303

The binary LS I +61$^{\circ}$ 303 was discovered as a gamma ray emitter nearly fifty years ago and has since been the subject of extensive observations across the electromagnetic spectrum. Composed of a primary Be star and a neutron star, LS I +61$^{\circ}$ 303 exhibits complex periodic behavior and variability from radio wavelengths to very-high-energy gamma rays (VHE, E>100 GeV), with timescales between 0.27s and four years. With the orbital inclination only loosely constrained and multiple orbital models, the origin of the VHE variability remains unknown. We present VERITAS’ extensive set of observations with coincident observations from Swift-XRT and Fermi-LAT. We explore the binary’s VHE characteristics throughout its entire 26.5 day orbit and use Swift-XRT and Fermi-LAT data to search for correlations between x-ray, high-energy gamma ray, and VHE gamma ray emission to reveal common emission mechanisms.

Speaker: Anne Duerr (University of Utah)

16:04 High-energy gamma rays from cosmic rays escaping from microquasars

HAWC and LHASSO reported very high energy (VHE) gamma rays with energies exceeding 100 TeV from five Galactic black hole binaries. The spatial extent of the VHE gamma rays is several tens of pc, which is much larger than the size of a black hole binary system. Some black hole binaries have different gamma-ray spectra, some of which are steeper than predicted by the standard shock acceleration model. Although individual interpretations of the VHE gamma rays from the SS 433 and V4641 Sgr were discussed, a unified explanation for the five microquasars that emit VHE gamma rays has not yet been attempted. In this work, we try to understand the origin of the VHE gamma rays from microquasars in a unified way by considering CRs escaping from microquasars. To understand the distribution of escaping CRs around a microquasar, we solve the diffusion equation taking into account the finite size of the CR source and the continuous CR injection. We show that the energy spectrum in the emission region is described by a broken power law spectrum with one or two spectral breaks even though the total spectrum of escaping CRs is a single power law spectrum. We then show that the VHE gamma-ray spectra of five microquasars can be explained in a unified way, in which all five microquasars have the same energy spectrum of the escaping CRs without the high energy cutoff, $dN/dE\propto E^{-2}$, the same diffusion coefficient, and the same emission region.

Speaker: Yutaka Ohira (The University of Tokyo)

16:19 VERITAS observations of the Microquasar SS 433

Microquasars are increasingly recognized as efficient particle accelerators, potentially contributing to the cosmic-ray flux up to the knee. Among them, SS 433 stands out as a unique system with precessing relativistic jets embedded within the W50 supernova remnant. Recent detections of very-high- and ultra-high-energy (UHE) gamma rays from SS 433 have solidified its role as a key laboratory for studying particle acceleration in jet-powered astrophysical sources.
We present results from over 100 hours of observations of SS 433 with VERITAS, spanning more than a decade. These high-resolution measurements allow for a detailed morphological study of the eastern and western jet lobes with an angular resolution of <0.1°. By analyzing the spatial and spectral characteristics of the gamma-ray emission, we investigate the particle acceleration mechanisms within the jets or at the interaction between jets and ISM of W50.

Speaker: Tobias Kai Kleiner

16:34 X-ray Insights into Knot Dynamics and Particle Acceleration in the PeVatron Microquasar SS 433/W50

Since the recent detection of very-high-energy (VHE; $E>0.1$ TeV) gamma rays, microquasars have gained more and more attention as potential PeVatron candidates. Among them, the microquasar SS 433 and its nebula W50 stand out as the first to be detected in VHE gamma rays. HAWC and H.E.S.S. reported TeV gamma-ray emission from knot-like structures in the outer lobes, likely powered by jets launched from SS 433, suggesting that particle acceleration takes place in these knots. Motivated by these gamma-ray observations, an extensive X-ray observation campaign is currently underway. In particular, new Chandra observations of the western and eastern knots have been performed in 2023 and 2024. Combined with archival data from 2000-2003, this allows us to investigate, for the first time, proper motion and flux variations over a 20-year interval.
Our proper motion measurements revealed a hint of outward motion in these knots; however, the detected motion is dominated by the systematic uncertainty. Thus, we conservatively derived a velocity upper limit of $<0.04c$ at the innermost knots for a distance of 5.5 kpc. Assuming this apparent velocity corresponds to a shock speed, the upper limit is converted to an upstream velocity of $\gtrsim 5,000$ km/s in the shock rest frame, indicating efficient particle acceleration similar to that observed in young supernova remnants.
We also conducted detailed spectral analyses. Spatially resolved spectral analysis confirmed spectral softening from the innermost knots to the outer lobes, which is consistent with previous findings. Compared to the archival data in 2003, the spectral parameters (photon index and flux) remain almost constant over the 20-year period, except for a ~20% flux decrease found at the western head knot (w1). If this flux decrease is attributed to synchrotron cooling, the magnetic field would be locally enhanced to tens of $\mu$G at w1.
In this talk, I will present detailed analysis, results, and interpretation of these findings.

Speaker: Naomi Tsuji (University of Tokyo/ICRR)

15:20 → 16:50 .

15:20 → 16:50 DM: developments

15:20 The Cross-Disciplinary Hunt for Dark Matter: Machine Learning and Material Science Meet Astroparticle Physics

The age of WIMP-like dark matter direct detection is drawing to a close due to their non-detection at exquisitely sensitive liquid-noble detectors. However, models where the dark matter is lighter than the mass of a proton remain largely inaccessible to existing probes. Recently, molecular targets have emerged as particularly well-suited detector materials to look for this sub-GeV dark matter. In this talk, I will show how theoretical techniques from chemistry and material science can be used to design searches that are sensitive to the best-motivated models of sub-GeV dark matter. I will review the latest development in molecule-based direct detection techniques and introduce how machine learning can be used to explore the vast and intractable space of potential materials, optimizing for theoretically-motivated electronic properties relevant to dark matter interactions. I will then present new constraints on sub-GeV dark matter from searches of molecular UV and IR signatures in gas and ice giants in the solar system. These astrophysical searches provide powerful new probes of unexplored parameter space and complement existing strategies for detecting dark matter.

Speaker: Carlos Blanco

15:35 A novel low-background photomultiplier tube R12699 developed for xenon based detectors

We present the development and performance of a novel 2-inch low-background R12699 PMT for the next-generation xenon detectors. Developed through collaboration between the PandaX team and Hamamatsu Photonics K.K., this PMT exhibits low radioactivity, with approximately 0.08 mBq/PMT for $^{60}$Co and 0.06 mBq/PMT for the $^{238}$U late chain, achieving a 15-fold reduction compared to R11410 PMT used in PandaX-4T. The radon emanation rate is below 3.2 $\mu$Bq/PMT (@90% confidence level) and surface $^{210}$Po activity of less than 18.4 $\mu$Bq/cm$^2$. Cryogenic testing at -100 $^{\circ}$C showed an average gain of $4.23 \times 10^6$ at -1000 V and an average dark count rate of 2.5 Hz per channel. Compactness, low radioactivity, and robust electrical performance in the cryogenic temperature make the R12699 well-suited for rare-event searches, including dark matter and neutrino studies.

Speaker: Zhou Zhizhen

15:50 Design and Validation of Cryogenic Readout Electronics at 165K

This study presents the design of a cryogenic electronics system intended for use in liquid-xenon dark matter detectors. In conventional cryogenic experiments, analog signals are transmitted from low-temperature detectors to room-temperature electronics via coaxial cables and multiple feedthroughs. As the scale of detectors increases, the growing number of signal channels complicates engineering and raises costs. We propose a cryogenic electronics architecture that directly performs front-end amplification, analog-to-digital conversion (ADC), and digital signal processing at low temperatures (~165 K). This design drastically reduces the number of signal channels and the complexity of cabling, thereby alleviating integration challenges and cutting costs. Test results demonstrate that the power modules, preamplifiers, and digital systems function stably in a cryogenic environment. The ADC's performance under cryogenic conditions is currently undergoing experimental validation.

Speaker: Ms yang liu

16:05 Development of a GAGG-based low-background neutron detector

In rare events experiments, such as those devoted to the direct search of dark matter, a precise knowledge of the environmental gamma and neutron backgrounds is crucial for the design of appropriate shieldings. The neutron component is often poorly known due to the lack of a scalable detector technology for the measurement of low-flux neutron spectra in a short time.
Thanks to their high gadolinium content, we are investigating the possibility of using scintillating Gd$_3$Al$_2$Ga$_3$O$_{12}$ (GAGG) crystals as portable neutron detectors, in alternative to $^3$He counters. GAGG features a high scintillation light yield, good timing performance, and the capability of particle identification via pulse-shape discrimination. In a low-background environment, the distinctive signature produced by neutron capture on gadolinium, namely a $\gamma$-ray cascade releasing $\sim$8 MeV of total energy, and the efficient particle identification provided by GAGG would yield a background-free neutron capture signal.
In this contribution, we will present the characterization of a first GAGG detector prototype in terms of particle discrimination performance, intrinsic radioactive contamination, and neutron response. We will then discuss possible further developments of this detector technology towards the realization of a portable setup for the neutron spectrum measurement in various locations at the INFN Gran Sasso National Laboratory (LNGS).

Speaker: Yingjie Chu (Gran Sasso Science Institute)

16:20 Searching for Dark Matter with the RES-NOVA detector

The RES-NOVA project detects cosmic neutrinos (i.e., Supernovae) via coherent elastic neutrino-nucleus scattering (CEνNS) using archaeological Pb-based cryogenic detectors. The high CEνNS cross-section, due to the Pb's large atomic mass, and ultra-high radiopurity of archaeological Pb enable a highly sensitive, cm-scale observatory equally sensitive to all neutrino flavors. These features are also key for dark matter (DM) direct detection. RES-NOVA plans to conduct a direct detection campaign while waiting for neutrinos of astrophysical origin. Its sensitivity to low-energy nuclear recoils makes it excellent for detecting DM from our galactic halo. Under conventional WIMPs assumptions we project the expected sensitivity to DM particles with masses spanning over 4 orders of magnitude, revealing a complementary role to other existing ton-scale direct searches. Additionally, the relatively high natural abundance of Pb-207 enables RES-NOVA to detect spin-dependent interactions, making it suitable for a wide range of theoretical well-motivated dark matter candidates.

This dual capability allows for the search of dark matter particles directly scattering off nuclei in earth-based detectors and, at the same time, their possible imprint in astrophysical neutrinos, opening new intriguing possibilities for the search and characterization of dark matter particles.

Speaker: Nahuel Ferreiro Iachellini (University of Milano-Bicocca)

16:35 Characterization of the Piedicastello Tunnels as a Potential Underground Laboratory for Astroparticle Physics in Trento, Italy

In the context of astroparticle physics, nuclear astrophysics, and quantum computing projects, identifying underground laboratories where cosmogenic background is suppressed is crucial.
Located approximately 500 meters from the center of Trento, Italy, the Piedicastello tunnels are covered by 100 meters of limestone rock from the Doss Trento hill. The site spans over 6,000 square meters and is currently used for events, temporary exhibitions, and educational activities. The cosmogenic background was measured at different locations within the Piedicastello tunnels using three portable scintillator telescopes with varying geometrical acceptances. In the deepest section, the measured muon flux was found to be approximately two orders of magnitude lower than at the surface. This preliminary measurement suggests that the site could serve as a facility requiring low environmental background conditions.

Speaker: Francesco Nozzoli (Universita degli Studi di Trento and INFN-TIFPA (IT))

15:20 → 16:50 GA: extensive air shower detectors

15:20 Classification of Unidentified Extended LHAASO Sources based on their Gamma-Ray Morphology: Prospects for Future IACTs.

While Supernova Remnants (SNRs) are widely considered the primary accelerators of cosmic rays (CRs) up to hundreds of TeV, they struggle to account for the CR flux at PeV energies, suggesting the existence of additional PeVatrons. Observations from LHAASO have identified several PeVatron candidates, including some SNRs, pulsar wind nebulae, TeV halos and young massive star clusters (YMSCs). These objects accelerate particles that interact with the surrounding interstellar medium and radiation fields, producing very-high-energy gamma rays (>100 TeV), a key signature of both leptonic and hadronic PeVatrons.

We simulate and model the emission of TeV halos and YMSCs, adopting radial emission profiles derived from observational data. Given the current angular resolution of gamma-ray instruments, these profiles often appear similar, making it challenging to distinguish between source classes. We explore how next-generation Imaging Atmospheric Cherenkov Telescopes (IACTs), namely the CTAO and the ASTRI Mini-Array, can classify these sources based on their morphology. We test our classification methods, derived from the profile features of known sources, on simulated CTAO and ASTRI Mini-Array observations of unidentified extended sources from the first LHAASO catalog.

We present the results of our analysis to highlight the potential of future IACT observations in identifying the nature of extended gamma-ray sources, refining PeVatron candidate classifications, and improving our understanding of cosmic-ray accelerators.

Speaker: Alberto Bonollo

15:35 The AdvCam project: Designing the future cameras for the Large-Sized Telescope of the Cherenkov Telescope Array Observatory.

An international collaboration composed of Italian, Japanese, Spanish and Swiss institutes, is developing the advanced camera (AdvCam), the next-generation camera for Imaging Atmospheric Cherenkov Telescopes, designed specifically for the Large-Sized Telescopes (LST) of the Cherenkov Telescope Array Observatory. AdvCam incorporates cutting-edge Silicon Photomultipliers (SiPMs) and a fully digital readout system, setting new standards for performance and efficiency.

The upgraded camera will feature four times more pixels for the same field of view as the existing PMT-based camera, enabling finer image resolution and significantly improving angular precision and background noise rejection. To cope with the increase in number of pixels, many technological challenges are being tackled, from low power and high speed integrated chip design to real-time data processing on hardware accelerators.

This technological leap will lower the energy threshold by allowing operation at lower observation threshold and providing brighter images. The increase in effective area, angular resolution and energy resolution will enhance the sensitivity, unlocking new potential for gamma-ray astronomy. In this work, we present the performance of the AdvCam’s core building blocks and its innovative architecture capable of enabling unprecedented triggering capabilities. We also showcase the latest performance results based on Monte-Carlo data that has been tuned to reflect the latest stages of the on-going technological developments, highlighting the transformative capabilities of this next-generation instrument.

Speaker: Matthieu Heller (Universite de Geneve (CH))

15:50 The trigger design for AdvCam

The AdvCam is a next-generation camera for the Large-Sized Telescopes of the Cherenkov Telescope Array Observatory, based on silicon photomultipliers. Its fully digital readout system enables the design of new, sophisticated trigger logic.

The Large-Sized Telescopes aim to cover the low-energy range of the cosmic gamma-ray spectrum, with a threshold starting at about 20 GeV, using the existing photomultiplier tube camera. The AdvCam, along with the new trigger logic, as shown by simulations, lowers the detectable energy
threshold to 13 GeV.

The proposed trigger logic has a multilevel structure. The first level involves fast coincidences among small pixel regions at a rate of approximately 1 GHz, while the second level processes all camera pixels within an approximately 10-nanosecond time window. Different families of machine learning algorithms optimized for FPGAs form the second-level trigger. In this work, we consider two main approaches: Deep Neural Networks and Density-Based Spatial Clustering of Applications with Noise, both running with latencies below 1 microsecond at a 1 MHz rate. This work provides a detailed description of the trigger chain and its performance, as studied through simulation.

Speaker: Dr Leonid Burmistrov (University of Geneva)

16:05 First observational results with the prototype experiment of stereoscopic water Cherenkov detector in Tibet

We have built a prototype of stereoscopic water Cherenkov detector array (SWCDA) inside the Tibet ASgamma air-shower array (Tibet-III array) by the end of 2024. The SWCDA project is the next generation of innovative ground-based stereoscopic water Cherenkov detection array, its main scientific goal is to observe 100GeV-10TeV high-energy gamma-ray astronomy, such as observation of blazars, active galactic nuclei (AGN/ AGN flare) and gamma-ray bursts (GRBs). This report will describe the observation results of prototype experiments of stereoscopic water Cherenkov detection array in detail.

Speaker: Prof. Huang Jing huangjing (Institute of High Energy Physics, CAS)

16:20 PEPS: Probing Extreme PeVatron Sources

The project Probing Extreme PeVatron Sources (PEPS) aims at measuring the most energetic $\gamma$-rays from our Galaxy in the energy range between $10^{15}$ eV and $5\times 10^{16}$ eV, opening a new energy window for multimessenger astroparticle physics. PEPS will consist of an array of 10 km$^2$ placed in the southern hemisphere, at the location of the Pierre Auger Observatory. It will be built in two phases. Already the first phase, with a surface of 2 km$^2$, will be the largest detector for $\gamma$-rays compared to the existing experiments. The location offers an excellent view of the Galactic Plane and the Galactic Center while taking advantage of the existing infrastructure of the Pierre Auger Observatory. The design is based on an array of water-Cherenkov particle detectors with a horizontal segmentation of the optical volume in two. We present the performances of two prototype detectors that are functioning in the field. The science case for PEPS will be detailed with an emphasis on the expected sensitivities to point sources, diffuse flux, and super-heavy dark matter.

Speaker: Ioana Maris

16:35 Results and plans to apply interferometry to air shower observations at the Pierre Auger Observatory

By analyzing the radio emissions from air showers using interferometry, we can estimate their properties. In this contribution, we apply interferometry to reconstruct air-shower parameters based on measurements taken with the Auger Engineering Radio Array (AERA) at the Pierre Auger Observatory. This reconstruction method is achievable at AERA through precise clock synchronization with a beacon and an accurate survey of the station locations. Interferometry has been applied to several thousand inclined air-shower observations for the first time, which allows for tests on the performance of air-shower geometry reconstruction, recovery of the radio signal from low-energy air showers, and methods to study the polarization of the radio-emission mechanisms. Additionally, in this contribution, we will also provide an overview of efforts to enable interferometry for the recently installed radio detectors that are part of the AugerPrime upgrade.

Speaker: Harm Schoorlemmer (Radboud University)

15:20 → 16:50 GWMS: intensity interferometry

Convener: Dr Nicolas Produit (Universite de Geneve (CH))

15:20 Observations of Fast Rotating Stars with the VERITAS Stellar Intensity Interferometer (VSII)

Abstract: The VERITAS Stellar Intensity Interferometer (VSII) uses an intensity interferometric technique to measure the angular extent of stellar envelopes of hot (OBA) stars and binary systems. VSII has previously demonstrated the ability to reconstruct the sub-milliarcsecond angular diameters of individual stellar photospheres (eps Ori, bet CMa, bet Uma) with a precision better than 5%. Recent improvements in instrumentation and analysis have enabled VSII to reconstruct highly deformed 2-D stellar photospheres of fast-rotating stars, such as gam Cas. In this talk, I will describe recent VSII observations of fast-rotating stars and the VSII sensitivity for measuring the equatorial elongation and orientation of deformed stellar photospheres. We compare the reconstructed VSII photosphere with a simulated PHOENIX model of a fast rotator.

Speaker: Dave Kieda

15:35 Prospects and first optical intensity interferometry results with the MAGIC and CTAO-North LST telescopes

Along with their gamma-ray observations at very high energies (VHE, 20 GeV - 100 TeV), the two 17-m MAGIC telescopes (at Roque de los Muchachos Observatory, La Palma, Spain) have also been utilized as an optical stellar intensity interferometer (SII) for the last six years. The calibration and validation of the setup, alongside the first measurement of the stellar angular diameter of 13 early-type stars, were published in a performance paper in early 2024. Around the same time, the technical advancements developed for MAGIC were applied to the first Large-Sized Telescope of the northern hemisphere array of the Cherenkov Telescope Array Observatory (CTAO-North LST-1), a 23-m diameter telescope located near MAGIC. Three more LSTs should be completed beginning of 2026 and they may be equipped in the same manner as LST-1. We will focus on our first measurements with the MAGIC+LST-1 SII and our prospects for this and the MAGIC+LST1-4 SII for the study of several objects that are also known to emit in gamma rays: novae, such as T CrB; winds from early-type stars, particularly colliding-wind binaries; and Be stars which are typical companions of compact objects in VHE gamma-ray binaries.

Speaker: Irene Jiménez Martínez (Max Planck Institute for Physics)

15:42 Resolving Binary Systems down to Milli-Arcsecond Precision through Stellar Intensity Interferometry with MAGIC and LST-1

The MAGIC telescopes are two imaging atmospheric Cherenkov telescopes (IACTs) located at the Roque de los Muchachos Observatory (La Palma, Spain). Many observations performed with a high night-sky background have been dedicated to stellar intensity interferometry (SII), since very-high-energy (VHE, 20 GeV - 100 TeV) gamma-ray observations have reduced sensitivity during these periods. The observations performed between 2021 and 2023 resulted in the measurement of 13 new angular diameters of stars in the blue band, as reported in a performance paper published in 2024. In early 2024, the neighboring first Large-Sized Telescope (LST-1) of the Cherenkov Telescope Array Observatory was added to the optical interferometer. The high angular resolution and the broad simultaneous UV coverage achieved with this setup can be exploited to study binary systems, targeting massive stars with angular separations of the order of a few milli-arcseconds. These high-resolution observations can potentially resolve the orbital parameters of the binary system, the angular size of each component, and their brightness ratio. These observational properties are directly related to the physical components of the system and can be used to understand their stellar evolution. Furthermore, some of these binary systems are known to produce VHE gamma-ray emission via colliding stellar winds, making them perfect candidates to be studied with IACTs. Following the growing interest in SII in recent years, we present the status and detection capabilities for binary stellar systems using the MAGIC+LST-1 optical interferometer.

Speaker: Aramis Raiola (Universite de Geneve (CH))

15:49 Intensity Interferometry prospects with the CTAO

A resolved optical image of a gamma-ray emitter would be of enormous scientific interest. For gamma-ray sources associated with interacting stars (colliding winds or novae), stellar intensity interferometry (SII), envisioned as a second observing mode at the Cherenkov Telescope Array Observatory (CTAO), could yield images of the systems in visible light. Recent radius measurements of massive stars with the current generation of Cherenkov telescopes demonstrate that SII is practical, but a timely and intensive effort is needed before images of interacting stars are possible. Fortunately there is also much interesting stellar astrophysics to do along the way: simultaneous mass and radius measurements, resolving stellar oscillations, and imaging outflows from stars. This contribution will present a matrix of the challenges and scientific opportunities for SII at the CTAO.

Speaker: Prasenjit Saha (University of Zurich)

16:04 Reaching 10 microarcsec in the optical to resolve accretion disks

The quantum properties of a gas of bosons were predicted by Einstein 100 years ago. The first experimental measurements of its consequences were performed by Hanbury-Brown & Twiss in 1954, when measuring the size of bright stars by correlating the arrival times of photons detected by two optical telescopes. Extremely large telescopes, 10ps resolution single photon detectors bring the key improvements to reach, in the optical, angular resolutions better than these achieved in the radio by the Event Horizon Telescope and to obtain the first images of accretion disks around galactic compact objects, active galactic nuclei and quasars.

Speaker: Roland Walter (University of Geneva)

16:19 Development of sub 50 picosecond intensity interferometry for astrophysics

Recent developments in single-photon avalanche diodes (SPADs) have lowered detector time resolution to under tens of picoseconds full width half maximum (FWHM). In 1956, the pioneer experiment of Hanbury Brown and Twiss (HBT) on measuring the sizes of bright stars was limited by the time resolution of their detectors and their telescope size. The QUASAR project aims at building SPAD-based multichannel intensity interferometer to be installed on large optical telescopes with kilometers-long baselines, improving the S/N obtained by Hanbury Brown and Twiss by one million and aiming to reach EHT like resolution but in visible light.

In this work we report the results of laboratory test of SPAD detectors to observe the HBT effect in photon-counting mode. Using a simple laboratory setup, and cutting edge SPAD detectors we deduce a time accuracy of <50ps FWHM. Additionally, using thermal sources and narrow spectral filters we analyze the second order correlation function obtained from different light sources of continuous and lined spectrum. Results are discussed and compared with quantum optic models. Furthermore, we report on a setup, allowing to simulate and estimate the size of an artificial star of known size to verify the analysis and data correlation techniques employed in QUASAR project.

Speaker: Gilles Koziol

16:34 Limits on Atmospheric Broadening of the HBT Peak Using High-Speed Single-Photon Detectors

Recent advancements in single-photon detection, such as Single-Photon Avalanche Diodes (SPADs), have enabled picosecond-resolution measurements of photon arrival times. These technologies are crucial for applications like Satellite Laser Ranging (SLR) and Intensity Interferometry (II), where atmospheric effects on photon propagation remain a key limiting factor. Previous studies predicted 30-ps temporal fluctuations in photon arrival times due to atmospheric turbulence, potentially impacting high-precision timing experiments.

In this work, we investigate effects of the atmospheric broadening on zero-baseline intensity interferometry measurements in the lab and on a telescope with the Sun. We establish an upper limit of 6-ps RMS on the broadening of the Hanbury Brown and Twiss (HBT) peak induced by the atmosphere during observations of the Sun. Using a simple laboratory setup we show that the atmosphere should not affect the HBT peak for zero-baseline just because of time delays in the propagation time. We discuss techniques to measure non-zero baseline effects of atmosphere widening and provide estimations from theoretical considerations.

Speaker: Dr Vitalii Sliusar (University of Geneva)

15:20 → 16:50 NU: highlights & analysis

15:20 Recent Upgrades to TAROGE-M: Antarctic High-Mountain Radio Antenna Array for Detecting Near-Horizontal Ultra-High Energy Air Showers

TAROGE-M comprises autonomous radio antenna arrays operating at 180--450 MHz frequencies on top of ~2.7 km-high Mt. Melbourne in Antarctica, designed to detect near-horizontal ultra-high-energy (UHE) air showers with energies >0.3 EeV. The primary goal is to detect more of the so-called ANITA anomalous events — air-shower-like events from below the horizon, which cannot be explained by tau neutrinos in the Standard Model, so as to address their origins. Like ANITA, TAROGE-M is at high altitude with a broad view toward the horizon, and operates in radio-quiet Antarctica with strong and near-vertical geomagnetic field which enhances the radio signal. However, TAROGE-M's mountain-based setup makes the design simpler, the duty cycle higher, and the expansion easier, and thus achieves a comparable exposure to ANITA experiments within a few station-years of operation.
Since its initial detection of UHE cosmic rays (CRs) in 2020, TAROGE-M has undergone two major system upgrades. The first upgrade to a single station in February 2023 fulfilled a long-term operation extended until January 2024, including occasional operation powered by a small wind turbine in polar winter. It achieved ~195-day live time, corresponding to a 56% duty cycle. More detailed calibrations using drone-borne pulsers were conducted, complemented by the installation of a ground-based pulser for long-term calibration. The initial analysis result of 148-day data identified about 34 UHECR candidates, in agreement with simulations. With the second upgrade completed in January 2025, two stations are now operating with a more robust design to achieve reliable year-round functionality, and thus will enhance the search for ANITA anomalous events significantly. We present these system upgrades along with initial results from the CR search.

Speaker: Shih-Hao Wang (Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taiwan)

15:35 Unfolding the Muon Neutrino Spectrum with Eleven Years of IceCube Data

The IceCube Neutrino Observatory, a cubic-kilometre detector embedded in the glacial ice of the South Pole, is designed to detect neutrinos across a broad energy range, from a few GeV to several PeV. This enables precise measurements of the neutrino energy spectrum, comprising the diffuse astrophysical flux, the conventional atmospheric flux from pion and kaon decays, and the not yet detected prompt neutrino flux from charmed hadron decays. Investigating the prompt component, expected to dominate in the crossover region between the other two, is a critical focus for understanding neutrino interactions, atmospheric processes, and cosmic ray composition.

This analysis determines the muon neutrino energy spectrum in the sensitive energy range between 500 GeV and 4 PeV with eleven years of IceCube data. We used an unfolding technique, which allows for model-independent determination and re-bins the observable space to ensure sufficient statistics at the highest energies. In addition to improving the precision of intermediate-energy spectral measurements, it provides the first reconstruction of the muon neutrino flux across five zenith angle bins from 86° to 180°, increasing IceCube’s energy range and enabling comparisons with theoretical models and prior measurements.

Speaker: Ms Lene van Rootselaar (TU Dortmund University)

15:50 Measuring the Astrophysical Neutrino-Antineutrino Ratio with IceCube

Recent measurements of astrophysical neutrinos have expanded our understanding of their nature and origin. However, very little is still known about the astrophysical $\nu/\bar{\nu}$ ratio. The only prior measurement is the recent, single Glashow event seen by IceCube. Understanding the astrophysical $\nu/\bar{\nu}$ ratio has a bearing on multiple questions, including the astrophysical spectral shape and neutrino production mechanisms. This analysis uses a new approach to measuring the astrophysical muon $\nu/\bar{\nu}$ ratio at various energies. It uses inelasticity, the fraction of the initial neutrino energy carried away by the hadronic shower. Inelasticity probes the $\nu/\bar{\nu}$ ratio due to the fact that at energies below roughly 100 TeV, valence quarks dominate in deep inelastic scattering interactions, leading to different neutrino and antineutrino inelasticities and cross-sections. We use 10.3 years of IceCube data consisting of starting tracks at energies between 1 TeV and 1 PeV with a self-veto selection that enhances astrophysical event purity in the down-going direction. Based on this sample and analysis method, we present the first measurement of the astrophysical $\nu/\bar{\nu}$ ratio at sub-PeV energies.

Speaker: Barbara Skrzypek (UC Berkeley)

16:05 Bayesian neutrino oscillation analysis with 715 kton-yr of KM3NeT/ORCA

KM3NeT/ORCA is a water-Cherenkov neutrino telescope currently under construction in the Mediterranean Sea, aimed at measuring atmospheric neutrino oscillations and determining the neutrino mass ordering. The detector consists of a three-dimensional array of detection units, each equipped with 18 digital optical modules, which house 31 photomultiplier tubes. The Cherenkov light induced by charged particles produced in neutrino interactions is used to reconstruct the parent neutrino’s direction and energy, allowing for constraints on the oscillation parameters $\Delta m^{2}_{31}$ and $\theta_{23}$.

This work presents the first Bayesian neutrino oscillation analysis performed with KM3NeT, using 715 kton-years of exposure from the ORCA detector. An adaptive Metropolis-Hastings algorithm is employed to construct a Markov Chain Monte Carlo, which samples the posterior probability density function (PDF) in the multidimensional space spanned by oscillation and nuisance parameters. The credible region at 90\% Confidence Level for the oscillation parameters, $\Delta m^{2}_{31} \in [-2.61,-1.80]\times 10^{-3} \ \mathrm{eV^2}$ assuming Inverted Ordering ( $\Delta m^{2}_{31} \in [1.92,2.73]\times 10^{-3} \ \mathrm{eV^2}$ for Normal Ordering) and $\sin^2 \theta_{23} \in [0.37,0.62]$, are inferred from the marginal posterior PDF in what constitutes a novel statistical approach in the field of atmospheric neutrino oscillations. Moreover, the Bayesian approach is applied to perform inference on the higher-dimensional model of Non-Standard Neutrino Interactions.

Speaker: Alfonso Lazo (IFIC-Universitat de València)

16:20 Search for cosmic neutrino point sources and extended sources with 6-21 lines of KM3NeT/ARCA

The identification of cosmic objects emitting high energy neutrinos provides new insights about the Universe and its active sources. The existence of cosmic neutrinos has been proven by the IceCube Neutrino Observatory, however the big question of where these neutrinos originate from remains largely unanswered. The KM3NeT detector for Astroparticle Research with Cosmics in the Abyss (ARCA) is currently being built in the Mediterranean Sea. It will have an instrumented volume of a cubic kilometre, and will excel at identifying cosmic neutrino sources due to its unprecedented angular resolution (< 0.1 degree for muon neutrinos with E > 300 TeV). KM3NeT has a view of the sky complementary to IceCube, and is sensitive to neutrinos across a wide range of energies. Currently more than 10% of the detector is installed in the deep sea. This contribution will present the results of point source and extended catalogue sources, as well as an all-sky scan looking for potential neutrino sources, with KM3NeT/ARCA data taken between May 2021 and September 2023 with an evolving detector geometry up to 21 lines.

Speaker: Vittorio Parisi (University of Genova)

16:35 Measuring the galactic plane and searching for galactic PeVatrons using the IceCube Multi-Flavor Astrophysical Neutrino sample

The IceCube Neutrino Observatory has provided new insights into the high-energy universe, in particular, unveiling neutrinos from the galactic plane. However, galactic neutrino sources are still unresolved. The recent detection of multi-PeV photons by LHAASO from the Cygnus region highlights its potential as a galactic neutrino source. Additionally, LHAASO, HAWC, and HESS have reported over forty galactic gamma-ray sources with energies above 100 TeV. Detecting neutrinos correlated with high-energy gamma-ray sources would provide compelling evidence of cosmic-ray acceleration in these galactic sources. In this work, we compile a 12.3-year, full-sky, all-flavor dataset, the IceCube Multi-Flavor Astrophysics Neutrino sample (ICEMAN). ICEMAN is the combination of three largely independent neutrino samples of different event morphologies, and builds upon the previous work of the DNN-based cascade sample, Enhanced Starting Track Event Selection, and the Northern Track sample. Recent improvements in ice modeling and detector calibration are also incorporated into the cascade reconstruction. In addition to revisiting the galactic plane, we adopt two different analysis methods to search for galactic PeVatrons. First, we use a template-based approach to probe the Cygnus Cocoon region. Second, we use a point source hypothesis to find correlations between IceCube neutrinos and gamma-ray sources detected at energies greater than 100 TeV.

Speaker: Matthias Thiesmeyer (University of Wisconsin - Madison)

16:51 → 17:00 Break

17:00 → 18:30 PO-2

Thursday 24 July

08:30 → 09:00 Registration

09:00 → 10:20 Rapporteur Talks: CRI/SH

10:20 → 10:50 Coffee

10:50 → 12:10 Rapporteur Talks: CRD/DM

12:10 → 13:10 Lunch

13:10 → 14:30 Rapporteur Talks: GA/GW

14:30 → 15:00 Coffee

15:00 → 16:20 Rapporteur Talks: NU/OE

16:20 → 16:50 Rapporteur Talks: Diversity, Inclusion & Early Career

16:50 → 17:10 Closing: Poster awards

17:10 → 17:40 Closing