Constraints on WIMP and Sommerfeld-Enhanced Dark Matter Annihilation from HESS Observations of the Galactic Center

Abstract

We examine the constraints on models of weakly interacting massive particle (WIMP) dark matter from the recent observations of the Galactic center by the High Energy Spectroscopic System (HESS) telescope. We analyze canonical WIMP annihilation into Standard Model particle final states, including b/b-bar, t/t-bar and W^+ W^-. The constraints on annihilation into b/b-bar is within an order of magnitude of the thermal cross section at ~3 TeV, while the tau^+/tau^- channel is within a factor of ~2 of thermal. We also study constraints on Sommerfeld-enhanced dark matter annihilation models, and find that the gamma-ray observational constraints here rule out all of the parameter space consistent with dark matter annihilation interpretations of PAMELA and the Fermi-LAT e^+/e^- spectrum, in specific classes of models, and strongly constrains these interpretations in other classes. The gamma-ray constraints we find are more constraining on these models, in many cases, than current relic density, cosmic microwave background, halo shape and naturalness constraints.