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Dark matter annihilation or unresolved astrophysical sources? Anisotropy probe of the origin of the cosmic gamma-ray background

Ando, Shin'ichiro and Komatsu, Eiichiro and Narumoto, Takuro and Totani, Tomonori (2007) Dark matter annihilation or unresolved astrophysical sources? Anisotropy probe of the origin of the cosmic gamma-ray background. Physical Review D, 75 (6). Art. No. 063519. ISSN 2470-0010. doi:10.1103/PhysRevD.75.063519.

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The origin of the cosmic gamma-ray background (CGB) is a longstanding mystery in high-energy astrophysics. Possible candidates include ordinary astrophysical objects such as unresolved blazars, as well as more exotic processes such as dark matter annihilation. While it would be difficult to distinguish them from the mean intensity data alone, one can use anisotropy data instead. We investigate the CGB anisotropy both from unresolved blazars and dark matter annihilation (including contributions from dark matter substructures), and we find that the angular power spectra from these sources are very different. We then focus on detectability of dark matter annihilation signals using the anisotropy data by treating the unresolved blazar component as a known background. We find that the dark matter signature should be detectable in the angular power spectrum of the CGB from two-year all-sky observations with the Gamma Ray Large Area Space Telescope (GLAST), as long as the dark matter annihilation contributes to a reasonable fraction, e.g., >~0.3, of the CGB at around 10 GeV. We conclude that the anisotropy measurement of the CGB with GLAST should be a powerful tool for revealing the CGB origin, and potentially for the first detection of dark matter annihilation.

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Komatsu, Eiichiro0000-0002-0136-2404
Additional Information:© 2007 The American Physical Society. (Received 16 December 2006; revised 1 February 2007; published 27 March 2007) S.A. and E.K. would like to thank Jennifer Carson for useful discussions. S.A. is also grateful to Edward Baltz, Marc Kamionkowski, Stefano Profumo, and Lawrence Wai for comments. S.A. was supported by Sherman Fairchild Foundation at Caltech. E.K. acknowledges support from the Alfred P. Sloan Foundation. T.N. and T.T. were supported by a Grant-in-Aid for the 21st Century COE "Center for Diversity and Universality in Physics" from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
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Sherman Fairchild FoundationUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Ministry of Education, Culture, Sports, Science and Technology (MEXT)UNSPECIFIED
Issue or Number:6
Record Number:CaltechAUTHORS:ANDprd07
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ID Code:8106
Deposited By: Archive Administrator
Deposited On:30 Jul 2007
Last Modified:08 Nov 2021 20:48

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