A Multi-frequency analysis of dark matter annihilation interpretations of recent anti-particle and gamma-ray excesses in cosmic structures (1508.01386v6)

Abstract: The Fermi-LAT observation of a gamma-ray excess from the galactic-centre, as well as the PAMELA, AMS, and AMS-2 anti-particle excesses, and the recent claim of a Fermi-LAT excess in the Reticulum-2 dwarf galaxy have been put forward as signatures compatible with of neutralino dark matter. These are of particular interest as the neutralino annihilation models which fit these observations might have observable consequences from radio to gamma-ray emission. Since dark matter is expected to be a major matter constituent of cosmic structure, these multi-frequency consequences should also be common to structures across the mass spectrum. Thus, in this work we make predictions for the multi-frequency spectra of three well-known sources dominated by dark matter, e.g. the Coma cluster, the galaxy M81, and the Draco dwarf galaxy using models favoured by dark matter interpretations of the aforementioned observations. We pay special attention to the consequences for these models when their cross-sections are renormalised to reproduce the recent gamma-ray excess observed in the Reticulum-2 dwarf galaxy, which throw a dark matter interpretation of this excess into doubt. We find that the multi-frequency data of Coma and Draco disfavour the dark matter interpretation of the AMS, PAMELA and Fermi anti-particle excess. Models derived from Fermi-LAT galactic centre observations present somewhat lesser conflicts. We determine the detection prospects of the Square Kilometre Array, the Cherenkov Telescope Array, as well as the ASTROGAM and ASTRO-H satellites for the studied models. This demonstrates that ASTRO-H is well positioned to probe the X-ray emissions from neutralino annihilation. Thus, multi-frequency observation with the next generation experiments will allow for unprecedented sensitivity to the neutralino parameter space.