Detecting gamma-ray anisotropies from decaying dark matter: Prospects for Fermi LAT

被引:45
作者
Ibarra, Alejandro [1 ]
Tran, David [1 ]
Weniger, Christoph [2 ]
机构
[1] Tech Univ Munich, Phys Dept T30D, D-85748 Garching, Germany
[2] Deutsch Elektronen Synchrotron DESY, D-22607 Hamburg, Germany
来源
PHYSICAL REVIEW D | 2010年 / 81卷 / 02期
关键词
COMPTON-SCATTERING; EGRET OBSERVATIONS; POSITRON; RADIATION; PROBE; PROPAGATION; SPECTRUM;
D O I
10.1103/PhysRevD.81.023529
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Decaying dark matter particles could be indirectly detected as an excess over a simple power law in the energy spectrum of the diffuse extragalactic gamma-ray background. Furthermore, since the Earth is not located at the center of the Galactic dark matter halo, the exotic contribution from dark matter decay to the diffuse gamma-ray flux is expected to be anisotropic, offering a complementary method for the indirect search for decaying dark matter particles. In this paper we discuss in detail the expected dipolelike anisotropies in the dark matter signal, taking also into account the radiation from inverse Compton scattering of electrons and positrons from dark matter decay. A different source for anisotropies in the gamma-ray flux are the dark matter density fluctuations on cosmic scales. We calculate the corresponding angular power spectrum of the gamma-ray flux and comment on observational prospects. Finally, we calculate the expected anisotropies for the decaying dark matter scenarios that can reproduce the electron/positron excesses reported by PAMELA and the Fermi LAT, and we estimate the prospects for detecting the predicted gamma-ray anisotropy in the near future.
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页数:15
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