Evidence for "sterile neutrino" dark matter?

Abstract

I show that it may be possible to explain the present evidence for a gamma-ray emission from the galactic halo as due to halo WIMP annihilations. Not only the intensity and spatial pattern of the halo emission can be matched but also the relic density of the candidate WIMP can be in the cosmologically interesting domain. After a model-independent analysis to learn about the properties of a suitable candidate, I present a working model: a sterile neutrino in a model with an extended Higgs sector. Two examples indicate the existence of an interesting region in the model parameter space where present observational and experimental constraints are satisfied and the gamma-ray emission is reproduced.