Ruling out ~100–300 GeV thermal relic annihilating dark matter by radio observation of the andromeda galaxy

Over the past few years, some studies have claimed that annihilating dark matter with mass ~10–100 GeV can explain the GeV gamma-ray excess in our Galaxy. However, recent analyses of Fermi-LAT and radio observational data have ruled out the possibility of the thermal relic annihilating dark matter with mass m ≤ 100 GeV for some popular annihilation channels. By using the new observed radio data of the Andromeda galaxy, we rule out the existence of ~100–300 GeV thermal relic annihilating dark matter for 10 annihilation channels. The lower limits of annihilating dark matter mass are improved to larger than 330 GeV for the most conservative case, which is a few times larger than the current best constraints. Moreover, these limits strongly disfavor the benchmark model of weakly interacting massive particles produced through the thermal freeze-out mechanism. Copyright © 2019 The American Astronomical Society. All rights reserved.