scholarly journals Diffuse gamma-ray background and cosmic-ray positrons from annihilating dark matter

2009 ◽  
Vol 80 (2) ◽  
Author(s):  
Masahiro Kawasaki ◽  
Kazunori Kohri ◽  
Kazunori Nakayama
Keyword(s):  
Dark Matter ◽  
Gamma Ray ◽  
Cosmic Ray

scholarly journals Astroparticle Physics with H.E.S.S.: recents results and nearfuture prospects

2019 ◽  
Vol 209 ◽  
pp. 01054
Author(s):  
Emmanuel Moulin
Keyword(s):  
Dark Matter ◽  
Gamma Ray ◽  
Lorentz Invariance ◽  
Cosmic Ray ◽  
High Energy ◽  
New Physics ◽  
Galactic Centre ◽  
Astroparticle Physics ◽  
Dark Matter Search ◽  
Physics Program

H.E.S.S. is an array of five Imaging Atmospheric Cherenkov Telescopes located in Namibia. It is designed for observations of astrophysical sources emitting very-high-energy (VHE) gamma rays in the energy range from a few ten GeVs to several ten TeVs. The H.E.S.S. instrument consists of four identical 12 m diameter telescopes and a 28 m diameter telescope placed at the center of the array. An ambitious Astroparticle Physics program is being carried out by the H.E.S.S. collaboration searching for New Physics in the VHE gamma-ray sky. The program includes the search for WIMP dark matter and axion-like particles, tests of Lorentz invariance, cosmic-ray electron measurements, and search for intergalactic magnetic fields. I will present the latest results on dark matter search from the observations of the Galactic Centre region, the search for Lorentz invariance violation with the 2014 flare observation of Markarian 501, and the first measurement of the cosmic-ray electron spectrum up to 20 TeV. The future of the H.E.S.S. Astroparticle Physics program will be discussed.

scholarly journals Indirect searches for dark matter with the Fermi LAT instrument

2014 ◽  
Vol 29 (22) ◽  
pp. 1430030 ◽  
Author(s):  
M. N. Mazziotta ◽  
Keyword(s):  
Dark Matter ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
Weakly Interacting Massive Particles ◽  
Current Status ◽  
Large Area ◽  
Weakly Interacting ◽  
Electron Positron ◽  
Massive Particles ◽  
Particle Dark Matter

In this review the current status of several searches for particle dark matter with the Fermi Large Area Telescope instrument is presented. In particular, the current limits on the weakly interacting massive particles, obtained from the analyses of gamma-ray and cosmic ray electron/positron data, will be illustrated.

scholarly journals Cosmic Gamma Ray Constraints on the Indirect Effects of Dark Matter

Particles ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 336-344 ◽  
Author(s):  
Konstantin M. Belotsky ◽  
Airat Kh. Kamaletdinov ◽  
Ekaterina S. Shlepkina ◽  
Maxim L. Solovyov
Keyword(s):  
Dark Matter ◽  
Gamma Radiation ◽  
Indirect Effects ◽  
Gamma Ray ◽  
Indirect Evidence ◽  
Cosmic Ray ◽  
High Energy ◽  
Observational Constraint ◽  
Atom Model ◽  
Suppression Effects

The observed anomalous excess of high-energy cosmic ray (CR) positrons is widely discussed as possible indirect evidence for dark matter (DM). However, any source of cosmic positrons is inevitably the source of gamma radiation. The least model dependent test of CR anomalies interpretation via DM particles decays (or annihilation) is connected with gamma-ray background due to gamma overproduction in such processes. In this work, we impose an observational constraint on gamma ray production from DM. Then, we study the possible suppression of gamma yield in the DM decays into identical final fermions. Such DM particles arise in the multi-component dark atom model. The influence of the interaction vertices on the gamma suppression was also considered. No essential gamma suppression effects are found. However, some minor ones are revealed.

scholarly journals Polynomial spectrum of gamma ray from dark matter

2017 ◽  
Vol 32 (33) ◽  
pp. 1745001 ◽  
Author(s):  
Yong Tang
Keyword(s):  
Dark Matter ◽  
Power Law ◽  
Wide Class ◽  
Degrees Of Freedom ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
Gamma Line ◽  
Polynomial Type ◽  
Model Independent ◽  
Positive Index

In this paper, we present some general features of gamma-ray spectra from dark matter (DM). We find that the spectrum with sharp features could appear in a wide class of DM models and mimic the gamma line signals. If all other physical degrees of freedom are heavy or effectively decoupled, the resulting gamma ray from DM decay or annihilation would generally have polynomial-type spectra or power-law with positive index. We illustrate our findings in a model-independent framework with generic kinematic analysis. Similar results can also apply for cosmic ray or neutrino cases.

scholarly journals Constraining primordial black hole fraction at the galactic centre using radio observational data

2020 ◽  
Vol 497 (1) ◽  
pp. 1212-1216
Author(s):  
Man Ho Chan ◽  
Chak Man Lee
Keyword(s):  
Dark Matter ◽  
Gamma Ray ◽  
Minor Component ◽  
Cosmic Ray ◽  
Galactic Centre ◽  
Primordial Black Hole ◽  
Primordial Black Holes ◽  
Mass Distributions ◽  
Large Parameter Space ◽  
Hole Fraction

ABSTRACT Recent gamma-ray and cosmic-ray observations have put strong constraints on the amount of primordial black holes (PBHs) in our universe. In this paper, we use the archival radio data of the inner Galactic Centre to constrain the PBH to dark matter ratio for three different PBH mass distributions including monochromatic, lognormal, and power law. We show that the amount of PBHs only constitutes a very minor component of dark matter at the Galactic Centre for a large parameter space.

scholarly journals Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth

Science ◽  
2017 ◽  
Vol 358 (6365) ◽  
pp. 911-914 ◽  
Author(s):  
A. U. Abeysekara ◽  
A. Albert ◽  
R. Alfaro ◽  
C. Alvarez ◽  
J. D. Álvarez ◽  
...  
Keyword(s):  
Dark Matter ◽  
High Altitude ◽  
Secondary Production ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
High Flux ◽  
Emission Profile ◽  
Electron Volt ◽  
Local Sources ◽  
Positron Flux

The unexpectedly high flux of cosmic-ray positrons detected at Earth may originate from nearby astrophysical sources, dark matter, or unknown processes of cosmic-ray secondary production. We report the detection, using the High-Altitude Water Cherenkov Observatory (HAWC), of extended tera–electron volt gamma-ray emission coincident with the locations of two nearby middle-aged pulsars (Geminga and PSR B0656+14). The HAWC observations demonstrate that these pulsars are indeed local sources of accelerated leptons, but the measured tera–electron volt emission profile constrains the diffusion of particles away from these sources to be much slower than previously assumed. We demonstrate that the leptons emitted by these objects are therefore unlikely to be the origin of the excess positrons, which may have a more exotic origin.

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