Anisotropy probe of galactic and extra-galactic dark matter annihilations
- University of Padova and INFN sezione di Padova, via Marzolo 8, 35131 Padova, Italy and Institut d'Astrophysique de Paris, boulevard Arago 89bis, 75014 Paris (France)
We study the flux and the angular power spectrum of gamma rays produced by dark matter (DM) annihilations in the Milky Way (MW) and in extra-galactic halos. The annihilation signal receives contributions from: (a) the smooth MW halo, (b) resolved and unresolved substructures in the MW, (c) external DM halos at all redshifts, including (d) their substructures. Adopting a self-consistent description of local and extra-galactic substructures, we compute the angular power spectrum of gamma-ray anisotropies and show that, quite independently from the prescription used for the concentration parameters c(M,z), an interesting signature of DM annihilations could soon be discovered by the Fermi LAT satellite at low multipoles, l{approx}100, assuming a particle physics scenario that does not violate gamma-ray constraints from the Galactic center. The DM contribution to the angular power spectrum is dominated by MW substructures (with mass M{>=}10{sup 4}M{sub {center_dot}}), while, at least for the substructures' models that we have adopted, the contribution of extra-galactic annihilations is negligible at all scales. MW subhalos also dominate the annihilation flux in the majority of the sky, with the smooth galactic halo being brighter only in the very central region.
- OSTI ID:
- 21316206
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 80, Issue 2; Other Information: DOI: 10.1103/PhysRevD.80.023518; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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