MeV Dark Matter: Has It Been Detected?

Abstract

We discuss the possibility that the recent detection of 511 keV $\gamma$ rays from the galactic bulge, as observed by INTEGRAL, is a consequence of low mass ($1–100\mathrm{MeV}$) particle dark matter annihilations. We discuss the type of halo profile favored by the observations as well as the size of the annihilation cross section needed to account for the signal. We find that such a scenario is consistent with the observed dark matter relic density and other constraints from astrophysics and particle physics.