Diffuse cosmic gamma-rays at 1-20 MeV: A trace of the dark matter?

Abstract

Several independent observations of the galactic core suggest hitherto unexplained sources of energy. The most well known case is the 511 keV line which has proven very difficult to explain with conventional astrophysical positron sources. A similar, but less well known mystery is the excess of gamma-ray photons detected by COMPTEL across a broad energy range 1-20 MeV. Such photons are found to be very difficult to produce via known astrophysical sources. We show in this work that dark matter in the form of dense antimatter droplets provides a natural explanations for the observed flux of gamma-rays in the 1-20 MeV range. We argue thatsuch photons must always accompany the 511 keV line as they produced by the same mechanism within our framework. We calculate the spectrum and intensity of the 1-20 MeV gamma-rays, and find it to be consistent with the COMPTEL data.