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

TL;DR

This paper investigates how annihilating dark matter could contribute to the extragalactic gamma-ray background and uses observations to constrain dark matter properties, especially the annihilation cross section.

Contribution

It provides new upper bounds on dark matter annihilation cross sections based on diffuse gamma-ray observations, considering different halo profiles.

Findings

Diffuse gamma-rays impose stringent constraints on dark matter models.

Cored halo profiles yield stronger bounds than Galactic center gamma-ray observations.

Future Fermi data will tighten these constraints further.

Abstract

We study the annihilating dark matter contribution to the extra-galactic diffuse gamma-ray background spectrum, motivated by the recent observations of cosmic-ray positron/electron anomalies. The observed diffuse gamma-ray flux provides stringent constraint on dark matter models and we present upper bounds on the annihilation cross section of the dark matter. It is found that for the case of cored dark matter halo profile, the diffuse gamma-rays give more stringent bound compared with gamma-rays from the Galactic center. The Fermi satellite will make the bound stronger.