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.

MODEL-INDEPENDENT STUDIES OF DARK MATTER

2011 ◽  
Vol 20 (08) ◽  
pp. 1441-1451 ◽  
Author(s):  
CHUAN-REN CHEN
Keyword(s):  
Dark Matter ◽  
Gamma Ray ◽  
Direct Detection ◽  
Cosmic Ray ◽  
Initial Energy ◽  
Tree Level ◽  
Negative Results ◽  
Adopted Model ◽  
Model Independent ◽  
Relic Abundance

The excess in cosmic-ray positrons and electrons observed by PAMELA, ATIC, PPB-BET and Fermi can be explained by dark matter decay or annihilation. On the other hand, the negative results from CDMS II and XENON direct detections of dark matter put an upper limit on the elastic-scattering cross section between dark matter and nucleon. We adopted model-independent approaches to study dark matter in cosmic-ray electrons, gamma-ray, relic density, direct detection experiments and LHC. We studied the distribution of the cosmic-ray electron flux observed at the Earth and found that it can reflect the initial energy spectrum of electrons generated from dark matter decay or annihilation even after propagation. We also derive constraints on the decay rate of dark matter into various two-body final states using Fermi and HESS gamma-ray data. We found that the μ+μ- or τ+τ- final state is favored in order to simultaneously explain electron excess and meet all gamma-ray constraints. Finally, we examined various tree-level induced operators of dimension six and constrain them using the current experimental data, including the WMAP data of the relic abundance and CDMS II direct detection of the spin-independent scattering. The implication of LHC search is also explored.

scholarly journals A MODEL-INDEPENDENT METHOD TO STUDY DARK MATTER INDUCED LEPTONS AND GAMMA RAYS

2012 ◽  
Vol 27 (35) ◽  
pp. 1250206 ◽  
Author(s):  
MINGXING LUO ◽  
LIUCHENG WANG ◽  
GUOHUAI ZHU
Keyword(s):  
Dark Matter ◽  
Compton Scattering ◽  
Gamma Rays ◽  
Particle Physics ◽  
Cosmic Ray ◽  
Propagation Model ◽  
Strong Constraint ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Model Independent

By using recent data, we directly determine the dark matter (DM)-induced e± spectrum at the source from experimental measurements at the earth, without reference to specific particle physics models. The DM-induced gamma rays emitted via inverse Compton scattering are then obtained in a model-independent way. However, the results depend on the choice of the astrophysical e± background, which is not reliably known. Nevertheless, we calculate, as an illustration, the fluxes of gamma rays from the Fornax cluster in the decaying DM scenario with various astrophysical e± backgrounds. Without any assumptions on details of the DM model, the predictions turn out to be either in disagreement with or only marginally below the upper limits measured recently by the Fermi-LAT Collaboration. In addition, these DM-induced ICS gamma rays in the GeV range are shown to be almost independent of choices of cosmic ray propagation model and of DM density profile, when a given astrophysical e± background is assumed. This provides a strong constraint on decaying DM scenario as the gamma rays may be produced in other processes besides inverse Compton scattering, such as the bremsstrahlung and neutral pion decays.

scholarly journals Study on the escape timescale of high-energy particles from supernova remnants through thermal X-ray properties

2020 ◽  
Vol 72 (5) ◽  
Author(s):  
Hiromasa Suzuki ◽  
Aya Bamba ◽  
Ryo Yamazaki ◽  
Yutaka Ohira
Keyword(s):  
Power Law ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
High Energy ◽  
Spectral Shape ◽  
X Ray ◽  
Galactic Cosmic Ray ◽  
High Energy Particles ◽  
Accelerated Particles

Abstract In the current decade, GeV/TeV gamma-ray observations of several supernova remnants (SNRs) have implied that accelerated particles are escaping from their acceleration sites. However, when and how they escape from the SNR vicinities are yet to be understood. Recent studies have suggested that the particle escape might develop with thermal plasma ages of the SNRs. We present a systematic study on the time evolution of particle escape using thermal X-ray properties and gamma-ray spectra using 38 SNRs associated with GeV/TeV gamma-ray emissions. We conducted spectral fittings on the gamma-ray spectra using exponential cutoff power-law and broken power-law models to estimate the exponential cutoff or the break energies, both of which are indicators of particle escape. Plots of the gamma-ray cutoff/break energies over the plasma ages show similar tendencies to those predicted by analytical/numerical calculations of particle escape under conditions in which a shock is interacting with thin interstellar medium or clouds. The particle escape timescale is estimated as ∼100 kyr from the decreasing trends of the total energy of the confined protons with the plasma age. The large dispersions of the cutoff/break energies in the data may suggest an intrinsic variety of particle escape environments. This might be the cause of the complicated Galactic cosmic ray spectral shape measured on Earth.

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 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 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.

Sign in / Sign up

Export Citation Format

Share Document