Dark matter signatures in a mostly unexplored gamma-ray energy window

Abstract

The energy range 0.3 MeV - 100 MeV between Compton and pair production regimes is unique for studying matter evolution, antimatter generation, very energetic phenomena in compact objects and massive black holes, and for resolving the Galactic Center region, still expected to be the brightest source of dark matter annihilations in the gamma-ray sky. Until now, instruments in this energy range lacked the sensitivity for a breakthrough that would require an efficient instrument working both in the Compton scattering regime, and in the electron-positron pair production regime at higher energies, with excellent background subtraction capability. The e-ASTROGAM Mission (M. Tavani, V. Tatischeff et al.) to be proposed to the 2016 ESA M5 Call for a mediumsize mission will add the as yet unexplored MeV - GeV range to dark matter investigations with excellent angular resolution and exposure. Models will be tested in a spectral range not currently studied in order to disentangle the possible dark matter contribution from the diffuse background, the point sources contribution and the other possible explanations.