The EGRET excess of diffuse gamma rays and the galactic dark matter halo

Abstract

The public data from the EGRET space telescope on diffuse galactic gamma rays in the energy range from 0.1 to 10 GeV are reanalyzed with the purpose of searching for signals of dark matter annihilation (DMA). The analysis confirms the previously observed excess for energies above 1 GeV in comparison with the expectations from conventional galactic models. In addition, the excess was found to show all the key features of a signal from DMA: (a) the excess is observable in all sky directions and has the same shape everywhere, thus pointing to a common source; (b) the shape corresponds to the expected spectrum of the annihilation of non-relativistic massive particles (50–90 GeV) into neutral π0 mesons, which decay into photons; (c) the excess traces the dark matter (DM) distribution in our galaxy, as proven by the reconstruction of the rotation curve from the intensity of the gamma ray excess. These signals of DMA are compatible with supersymmetry for boost factors of 20 upwards and have a statistical signifi...