The Gamma-Ray Halo from Dark Matter Annihilations

Abstract

A sophisticated analysis of EGRET data has found evidence for gamma-ray emission from the galactic halo. I entertain the possibility that part of the EGRET signal is due to WIMP annihilations in the halo. I show that a viable candidate with the required properties exists in a model with an extended Higgs sector. The candidate has a mass of 2--4 GeV, a relic density $\Omega \sim 0.1$ (for a Hubble constant of 60 km/s/Mpc), and a scattering cross section off nucleons in the range $10^{-5}$--$10^{-1}$ pb. The model satisfies present observational and experimental constraints, and makes strict predictions on the gamma-ray spectrum of the halo emission.

4 pages, 5 figures