Gamma-Ray Excess from the Galactic Center and Supergravity Models

Abstract

We analyse the effect of the compression of the dark matter due to the infall of baryons to the galactic center on the gamma-ray flux. In addition, we also consider the effect of non-universal supersymmetric soft terms. This analysis shows that neutralino dark matter annihilation can give rise to signals largely reachable by future experiments like GLAST. This is a remarkable result if we realise that direct detection experiments will only be able to cover a small region of the parameter space. Actually, in this SUGRA framework we have also been able to fit present excess from EGRET and CANGAROO using different non-universal scenarios, and even fit the data from both experiments with only one scenario. We have also studied the recent HESS data implying a neutralino heavier than 12 TeV. Because of such a heavy neutralino, it is not natural to find solutions in the SUGRA framework. Nevertheless we have carried out a quite model-independent analysis, and found the conditions required on the particle physics side to fit the HESS data thanks to dark matter annihilation.