A new target object for constraining annihilating dark matter

Abstract: In the past decade, gamma-ray observations and radio observations of our Milky Way and the Milky Way dwarf spheroidal satellite galaxies put very strong constraints on annihilation cross sections of dark matter. In this article, we suggest a new target object (NGC 2976) that can be used for constraining annihilating dark matter. The radio and x-ray data of NGC 2976 can put very tight constraints on the leptophilic channels of dark matter annihilation. The lower limits of dark matter mass annihilating via $e^+e^-$, $\mu^+\mu^-$ and $\tau^+\tau^-$ channels are 200 GeV, 130 GeV and 110 GeV respectively with the canonical thermal relic cross section. We suggest that this kind of large nearby dwarf galaxies with relatively high magnetic field can be good candidates for constraining annihilating dark matter in future analysis.