Dark matter annihilation in the local group

Abstract

Under the hypothesis of a dark matter composed by supersymmetric particles such as neutralinos, we investigate the possibility that their annihilation in the halos of nearby galaxies could produce detectable fluxes of $\ensuremath{\gamma}$ photons. Expected fluxes depend on several, poorly known quantities such as the density profiles of dark matter halos, the existence and prominence of central density cusps and the presence of a population of subhalos. We find that, for all reasonable choices of dark matter halo models, the intensity of the \ensuremath{\gamma}-ray flux from some of the nearest extragalactic objects, such as M31, is comparable to or higher than the diffuse galactic foreground. We show that next generation ground-based experiments could have the sensitivity to reveal such fluxes which could help us to unveil the nature of dark matter particles.