Conveners
Cosmic rays: I
- Manuela Vecchi (Universidade de Sao Paulo (BR))
Cosmic rays: II
- Nicola Tomassetti (Centre National de la Recherche Scientifique (FR))
Cosmic rays: III
- Damiano Caprioli (Princeton University)
Cosmic rays: IV
- Philipp Mertsch
We present a precision measurement of the cosmic-ray proton flux at rigidity from 1 GV to 1.8 TV and the helium flux at rigidity from 2 GV to 3 TV. The measurement is based on the data collected by the Alpha Magnetic Spectrometer experiment on the International Space Station. The two fluxes are found to progressively harden at rigidities larger than 100 GV, while the proton-to-helium ratio is...
Precision measurements by the Alpha Magnetic Spectrometer on the International Space Station of the primary cosmic-ray electron flux in the range 0.5 to 700 GeV and the positron flux in the range 0.5 to 500 GeV are presented. The electron flux and the positron flux each require a description beyond a single power-law spectrum. Both the electron flux and the positron flux change their behavior...
A precision measurement by AMS of the antiproton flux and
the antiproton-to-proton flux ratio in primary cosmic rays in the
absolute rigidity range from 1 to 450 GV is presented based on $3.49
\times 10^5$ antiproton events and $2.42 \times 10^9$ proton events. The
antiproton-to-proton flux ratio reaches a maximum at ∼20 GV and is
rigidity independent above 60.3 GV.
Astroparticle physics of Galactic cosmic rays (CR) has entered a new level of precision with the measurements of AMS-02. On the other hand, uncertainties in CR production in the sources and in their propagation are still large. We thus perform a global analysis of injection and propagation parameters testing how the current diffusion models perform in the light of the new precise data. Using...
One of the possible sources of hadronic cosmic rays (CRs) are newborn pulsars. If it is indeed the case, they should feature diffusive gamma-ray halos produced by interactions of CRs with interstellar gas. In my talk I will report on the attempts to identify extended gamma-ray emission around young pulsars making use of the 7-year Fermi-LAT data.
I will describe the method and the selected...
We present a combined analysis of the recent AMS-02 data on electrons, positrons, electrons plus positrons and positron fraction. We consider a self-consistent framework where we realize a theoretical modeling of all the astrophysical components that can contribute to the observed fluxes. The primary electron contribution is modeled through a smooth spatial distribution of distant supernova...
Since June 2006 the PAMELA satellite-borne experiment has presented fundamental results on various aspects of cosmic-ray physics. Above all, PAMELA investigated the features present in the antiparticle component of galactic cosmic rays, which have been interpreted in terms of DM annihilation or pulsar contribution. The combination of a permanent magnet with a silicon-strip spectrometer and a...
The nuclei fluxes with rigidity and their ratios are important for understanding the production, acceleration and propagation mechanisms of cosmic rays. Latest result from the Alpha Magnetic Spectrometer on the International Space Station of the light nuclei measurement will be presented.
In view of the latest publications of the primary CR fluxes, namely proton and helium flux from AMS-02 and CREAM, we aim at re-evaluating the positron flux coming from conventional astrophysical processes, i. e. secondary positrons. Moreover, we plan to estimate how the experimental uncertainties on the primary CR fluxes affect the secondary positron flux, computed by means of a new...
I will present the results of the scan of the parameter space for cosmic ray (CR) injection and propagation of Two-Halo-Model (THM). A Bayesian analysis is performed with Markov Chain Monte Carlo algorithm (MCMC). In THM, the propagation halo is divided into two different regions along the z-axis: inner and outer, where CRs will suffer from different propagation effects. We use proton and...
In the new “precision era” for cosmic ray astrophysics, theoretical predictions cannot content themselves with average trends,
but need to correctly take into account intrinsic uncertainties. The space-time discreteness of the cosmic ray sources, joined with a
substantial ignorance of their precise epochs and locations (with the possible exception of the most recent and close ones) plays...
Antinuclei are a very promising discovery channel for exotic cosmic ray sources such as decaying or annihilating dark matter and evaporating primordial black holes. This talk will present an improved calculation of the antideuteron background including also collisions of primary cosmic rays in supernova remnants and will discuss the discovery potential for antideuterons in the light of present...
I present the results of large kinetic (particle-in-cells) plasma simulations of particle acceleration at non-relativistic collisionless shocks, which in particular allow a first-principles investigation of diffusive acceleration at the blast waves of supernova remnants, the most prominent sources of Galactic cosmic rays (CRs).
Ion acceleration efficiency and magnetic field amplification are...
The mechanism through which cosmic rays (CRs) propagate away from their accelerators still remains an open issue. The main difficulty is the high non-linearity of the problem: CRs themselves excite the magnetic turbulence that confines them close to their sources. We solve numerically the coupled differential equations describing the evolution in space and time of the escaping particles and of...
The discovery of the Fermi bubbles - a huge bi-lobular structure seen in GeV gamma-rays above and below the Galactic center - implies the presence of a large reservoir of cosmic rays up to ~ 10 kpc from the disk. Diffuse shock acceleration, which is at work in known sources of cosmic rays, cannot explain the cosmic rays in the bubbles since there is no evidence for the presence of a strong...
We present DRAGON2, the new version of the well-known numerical package designed to simulate all processes related to cosmic-ray (CR) transport: diffusion (treated in a general, position-dependent way), reacceleration, advection, energy losses, nuclear processes.
This talk is focused on the propagation of hadrons, both from steady-state and transient sources in the Galaxy, discussing in...
The nature and the origin of ultra-high energy cosmic rays (UHECRs), above 10^{17} eV, is still unknown. The Pierre Auger Observatory has been operating for more then 10 years obtaining a number of major breakthroughs. To answer the open questions on UHECRs the Observatory was conceived as an hybrid detector consisting of fluorescence telescopes overlooking an array of water Cherenkov stations...
The Telescope Array (TA) is an observatory for the study of the highest energy cosmic rays (HECR). Located in Utah, U.S.A., TA consists of a surface scintillator array and a set of nitrogen fluorescence detectors which jointly allow hybrid reconstruction of cosmic ray induced extensive air showers. In this talk we will describe the cosmic ray energy spectrum as measured by TA over five orders...
Ultra high energy cosmic rays (UHECRs) are expected to be accelerated in astrophysical sources and to travel through extragalactic space before hitting the Earth atmosphere. They interact both with the environment in the source and with the intergalactic photon fields they encounter, causing different processes at various scales depending on the photon energy in the nucleus rest...
We fit the recent UHECR spectrum measurements from the Telescope Array
experiment under the assumption of pure proton composition, as assumed by the proton dip model.
We present a a full scan of the three main physical model parameters of
UHECR-injection: source redshift evolution, injected maximal proton energy
and spectral power-law index. We discuss how the result...
The HAWC Observatory in Sierra Negra, Mexico has recently recorded its trillionth cosmic-ray air shower in just over 1 year of operation. Using this high statistics data set, we have studied the arrival direction distribution of ~1-100 TeV cosmic rays. The sub-degree angular resolution of the air shower reconstruction allows us to examine the known features of the Northern TeV cosmic-ray sky...
The IceCube Neutrino Observatory has accumulated a total of 318 billion cosmic-ray induced muon events between May 2009 and May 2015. This data set was used for a detailed analysis of the cosmic-ray arrival direction anisotropy in the TeV to PeV energy range. The observed global anisotropy features large regions of relative excess and deficit, with amplitudes on the order of $10^{-3}$ up to...
The search for cosmic positron anisotropy has been performed using particles collected by the Alpha Magnetic Spectrometer on the International Space Station. The positron to electron ratio is consistent with isotropy at all energies and angular scales. The analysis of the positron to proton ratio yields consistent results.
Recent measurements of the dipole anisotropy in the arrival directions of Galactic cosmic rays (CRs) indicate a strong energy dependence of the dipole amplitude and phase in the TeV-PeV range. We argue here that these observations can be well understood within standard diffusion theory as a combined effect of (i) one or more local sources at Galactic longitude 120deg < l < 300deg dominating...
High energy cosmic ray electrons and positrons probe the local properties of
our Galaxy. In fact, regardless of the production mechanism, electromagnetic
energy losses limit the typical propagation scale of GeV-TeV electrons and
positrons to a few kpc.
In the diffusion model, the presence of nearby and dominant sources may produce
an observable dipole anisotropy in the cosmic ray...
IceTop and IceCube have observed a mysterious cold spot in the angular distribution of high energy ($\ge 100$ TeV) cosmic rays (CR), thereby placing interesting constraints on their transport properties. We examine here these constraints by comparing the observations with the predictions of pitch-angle diffusion in various kinds of turbulence. In the case of Alfvenic turbulence with a...
The Alpha Magnetic Spectrometer (AMS-02) has published the unprecedentedly precise measurement of the cosmic electron and positron spectra， as well as the positron fraction and anti-proton fraction. We have given a quantitative study on the AMS-02 results by a global fitting to the electron and positron spectra, together with the positron fraction data. The primary electron spectrum and the...
