Diffuse gamma-ray background and cosmic-ray positrons from annihilating dark matter

摘要

We study the annihilating dark matter contribution to the extra-galacticdiffuse gamma-ray background spectrum, motivated by the recent observations ofcosmic-ray positron/electron anomalies. The observed diffuse gamma-ray fluxprovides stringent constraint on dark matter models and we present upper boundson the annihilation cross section of the dark matter. It is found that for thecase of cored dark matter halo profile, the diffuse gamma-rays give morestringent bound compared with gamma-rays from the Galactic center. The Fermisatellite will make the bound stronger.