Anisotropy probe of galactic and extra-galactic Dark Matter annihilations

Abstract

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 show that the annihilation flux from substructures in the MW dominates over all the other components for angles larger than O(1) degrees from the Galactic Center, unless an extreme prescription is adopted for the substructures concentration. We also compute the angular power spectrum of gamma-ray anisotropies and find that, for an optimistic choice of the particle physics parameters, an interesting signature of DM annihilations could soon be discovered by the Fermi LAT satellite at low multipoles, l<100, where the dominant contribution comes from MW substructures with mass M>10^4 solar masses. For the substructures models we have adopted, we find that the contribution of extra-galactic annihilations is instead negligible at all scales.

14 pages, 7 figures

References in corpus (6)

• New Gamma-Ray Contributions to Supersymmetric Dark Matter Annihilation
• Dark Matter Annihilation in Substructures Revised
• Dark matter annihilation or unresolved astrophysical sources? Anisotropy probe of the origin of cosmic gamma-ray background
• The Likely Cause of the EGRET GeV Anomaly and its Implications
• Angular Signatures of Annihilating Dark Matter in the Cosmic Gamma-Ray Background
• Angular power spectrum of gamma-ray sources for GLAST: blazars and clusters of galaxies

Cited by in corpus (2)

• The Gamma-Ray-Flux Probability Distribution Function from Galactic Halo Substructure
• The angular power spectrum of the diffuse gamma-ray background as a probe of Galactic dark matter substructure