Conveners
Dark matter (indirect detection): I
- Carlos Perez de los Heros (Uppsala University)
Dark matter (indirect detection): II
- Fiorenza Donato
Dark matter (indirect detection): and Gamma-ray Astrophysics: joint session on the GC GeV excess
- Francesca Calore (University of Amsterdam)
- Marco Cirelli (CNRS LPTHE Jussieu)
Dark matter (indirect detection): IV
- Carlos Perez de los Heros (Uppsala University)
Dark matter (indirect detection): V
- Philip Von Doetinchem (University of Hawaii at Manoa)
- Miguel Sánchez-Conde (Oskar Klein Centre, Stockholm University)
One of the most promising way to detect dark matter is to look for its annihilation or decay products among cosmic-rays. Especially, it is found that quite strong constraints can be imposed by the gamma-ray measurements of dwarf spheroidal galaxies. However, recent studies reveal that these constraints are largely affected by the uncertainty of the dark matter halo density. In this talk, we...
We use the Maximum Likelihood technique to derive the density profile parameters of the the dark matter halos containing the Dwarf Spheroidal Galaxies of the Milky Way. This is done using the Jeans equation formalism on the the stellar kinematic data available for such systems. The method is validated on simulated data generated by the Gaia Challenge team.
The Diffuse Gamma-Ray Background (DGRB) collects the radiation produced by all those sources that are not bright enough to be resolved individually. Therefore, it represents an essential tool to study faint gamma-ray emitters, like star-forming or radio galaxies and the exotic Dark Matter. The anisotropy pattern of the DGRB is extremely informative: I will review the recent measurement of the...
Anisotropies in the electromagnetic emission produced by dark matter (DM) annihilation
or decay in the extragalactic sky are a recent tool in the quest for a particle DM evidence.
In particular, the angular two-point cross-correlation signal between non-gravitational DM emissions and the gravitational manifestation of DM has been shown to be a promising novel technique to disentangle a WIMP...
I will discuss a model-independent approach to calculate the spectra arising from dark matter annihilations or decays into intermediary particles with arbitrary spin, which subsequently produce neutrinos or photons via two-body decays. I illustrate this with two examples. First, with the neutrino spectra arising from dark matter annihilations into the massive Standard Model gauge bosons....
The morphology of dark matter annihilation/decay signals offers a handle for discrimination of dark matter against astrophysical backgrounds. Recent advances in N-body simulations allow us to map out the expected distribution of morphological parameters, rather than focusing on a small sample of halos which are assumed to be representative. In this talk, I will use data from the Illustris...
Dwarf spheroidal galaxies are among the most important targets in the search for gamma rays from dark matter annihilation in the cosmos. In fact, joint likelihood analyses using dozens of dwarfs have recently reached the sensitivity necessary to test the putative dark matter signal detected from the Galactic center. While the gamma-ray flux from conventional astrophysical emission processes...
The ISS-based CALET (Calorimetric Electron Telescope) detector is directly measuring the energy spectrum of electron+positron cosmic rays up to 20 TeV with an expected energy resolution of 2%. With an estimated proton rejection capability of 1 : 10$^5$ and an aperture of approximately 1200 cm$^2$ sr, it will provide good statistics even well above one TeV. This precise spectrum is going to be...
We developed a new semi-analytical method to better estimate the propagated cosmic-ray positron flux from a few hundreds MeV to 1 TeV.
It allows us to take into account Galactic convection, energy losses inside the disc and diffusive reacceleration, that are often neglected or badly considered
as most of the analyses concentrate on energies above 10 GeV.
Therefore, we are now able to...
The antiproton-to-proton ratio is about to be published by the AMS collaboration. Any excess with respect to the astrophysical background could potentially be the eagerly awaited signal for the presence of WIMPs inside the Milky Way. These massive and weakly interacting species are natural candidates for the astronomical dark matter. Pervading the Galaxy, they are expected to pair-annihilate...
The GAPS experiment is foreseen to carry out a dark matter search by hunting for low-energy cosmic-ray antideuterons with a novel detection approach. The theoretically predicted antideuteron flux resulting from secondary interactions of primary cosmic rays, e.g. protons, with the interstellar medium is very low. So far not a single cosmic antideuteron has been detected by any experiment, but...
Antideuterons are a potential messenger for dark matter annihilation or decay in our own galaxy, with very low backgrounds expected from astrophysical processes. The standard coalescence model of antideuteron formation, while simple to implement, has potentially large uncertainties from Monte Carlo modelling, and is under considerable strain by recent data from the LHC. We suggest two new...
The Sommerfeld enhancement is an important effect to modify the dark matter annihilation cross section if the dark matter couples with a force mediator whose mass is much smaller than the dark matter mass. Usually, the cross section is estimated as a product of the leading order cross section and the enhancement factor, which is calculated by solving Schrodinger equation with long range...
I will present recent results on the Galactic Center from the Fermi-LAT Collaboration using 6.5 years of LAT Pass 8 data, and comparisons with previous works. My talk will focus on our new analysis of the Galactic Center that includes the Fermi Bubbles in some detail; in particular I will show the effect on the previously reported Galactic excess from low-latitude emission from the Fermi...
Fermi-LAT observations have discovered a gamma-ray excess emanating from the Galactic center of the Milky Way. While this excess may be explained by populations of gamma-ray pulsars or by dark matter annihilation, it is worth noting that the intensity of this excess is comparable to the systematic uncertainties in the diffuse astrophysical gamma-ray emission near the Galactic plane. Thus, a...
The nature of the Galactic diffuse gamma-ray emission as measured by the Fermi Gamma-ray Space Telescope has remained an active area of research for the last several years. In particular, the discovery of a GeV excess towards the Galactic center has generated enormous interest in trying to understand its origins, whether astrophysical or more exotic. While most analyses of the GeV excess...
Several groups have demonstrated the existence of an excess in the gamma-ray emission around the Galactic Center (GC) with respect to the predictions from a variety of Galactic Interstellar Emission Models (GIEMs) and point source catalogs. The origin of this excess, peaked at a few GeV, is still under debate. A possible interpretation is that it comes from a population of unresolved...
An excess of diffuse gamma-rays towards the Galactic Center (GC) is usually assumed to originate from the GC with the most exciting interpretations being the contributions from dark matter (DM) annihilation and/or unresolved sources, like millisecond pulsars.
Up to now no studies have been undertaken to see if the excess occurs in other regions of the Galactic plane, which is a challenge,...
We present an interpretation of the excess in the gamma-ray emission from the center of our galaxy observed by Fermi-LAT in terms of dark matter annihilation within the scalar singlet Higgs portal model. In particular, we include the astrophysical uncertainties from the dark matter distribution and allow for unspecified additional dark matter components. We demonstrate through a detailed...
Super-Kamiokande (SK), a large water Cherenkov detector located
underground at the Kamioka Observatory in Japan,
can search for weakly interacting massive particles (WIMPs)
by detecting WIMP-induced neutrinos from the Sun and the Milky Way.
An excess of neutrinos from the Sun and Milky Way direction were
searched for compared to the expected atmospheric neutrino background.
For the...
The IceCube Neutrino Observatory is a cubic kilometer neutrino detector located in the deep clear ice below the surface at the geographic South Pole. In the pursuit of a better understanding of particle physics, IceCube can be used to detect dark matter indirectly through the self-annihilation to neutrinos. In this talk I will discuss the dark matter searches in IceCube, and present the latest results.
IceCube evidence for extraterrestrial neutrinos poses the intriguing puzzle concerning their origin. The 4-years IceCube HESE data show a 2-sigma excess at low energy (60 - 100 TeV) with respect to an astrophysical power-law with spectral index -2, predicted by the standard Fermi mechanism. Moreover, the IceCube MESE data exhibit an excess located in the same energy range in both southern and...
This talk is based on the recent review 1602.04816, which contains contributions from many different authors. Rather than focusing on any particular aspect, I aim to give a condensed summary of the status of the field.
In this talk, I would like to review how the combination of CMB power spectra, spectral distortions and BBN can be used to put stringeant constraints on the lifetime and abundance of exotic particles (such as dark matter but not only) with electromagnetic decay products. I will emphasize that this has the major advantages over cosmic rays of beeing (almost) free of theoritical uncertainties...
Axionlike particles (ALPs) are dark-matter candidates that occur in a variety of extensions of the Standard Model. Signatures of these particles could be detected at gamma-ray energies with the Fermi Large Area Telescope (LAT) due to the coupling of ALPs to photons in external electromagnetic fields. To date, Fermi-LAT observations provide the strongest constraints on the photon-ALP coupling...
VERITAS is an array of imaging atmospheric Cherenkov telescopes devoted to the study of the gamma-ray sky in the energy range between 85 GeV and > 30 TeV. VERITAS observations enable a broad program of scientific inquiry, including the study of extreme astrophysical sources both within and beyond our galaxy, the search for dark matter, and a number of topics in astroparticle physics. We...
The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is a continuously operated, wide field-of-view (FOV) observatory sensitive to 100 GeV - 100 TeV gamma rays. HAWC has been making observations since summer 2012 and officially commenced data-taking operations with the full detector in March 2015. With an instantaneous FOV of 2 steradians, HAWC observes 2/3 of the sky in 24 hours and...
The nature of dark matter (DM) is a longstanding enigma of physics; it may consist of particles beyond the Standard Model that are still elusive to experiments.
Indirect DM searches with the Fermi Gamma-ray Space Telescope and Imaging Atmospheric Cherenkov Telescopes (IACTs) are playing a crucial role in constraining the nature of the DM particle through the study of their annihilation into...
The past two decades have seen a rapid development of $\gamma$-ray astronomy, in particular at energies above a few hundred MeV where Fermi-LAT has revolutionised the field. As a result, extensive studies have been undertaken to characterise gamma-ray annihilation spectra of dark matter with masses above $\sim 1 \mathrm{\,GeV}$. However, due to the lacking sensitivity of current experiments at...
Dark matter decays or annihilations that produce line-like spectra may be smoking-gun signals. However, even such distinctive signatures can be mimicked by astrophysical or instrumental causes. We show that velocity spectroscopy-the measurement of energy shifts induced by relative motion of source and observer-can separate these three causes with minimal theoretical uncertainties. The...
It is well known that a star can capture dark matter (DM) particles, which
condense close to its center and eventually annihilate. In this work, we
trace capture, evaporation and annihilation rates
throughout the life of a massive star and show that it culminates in an
intense annihilation burst coincident with the death of the star in a core
collapse supernova. The reason is...
