2021/08/20 by Zi-Qing Xia, Zhao-Qiang Shen, Xia, Zi-Qing +7
Physics and Astronomy · #Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Gravitation Theories #Dark Matter and Cosmic Phenomena #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #High Energy Astrophysical Phenomena (astro-ph.HE)
paper · pdf · doi:10.48550/arxiv.2108.09204
openalex publication_date 2021/08/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Recently, the evidence for gamma-ray emission has been found in the Fermi-LAT observation for the outer halo of Andromeda galaxy (M31). The dark matter (DM) annihilation offers a possible explanation on the gamma-ray radiation. In this work, we focus on the dark matter annihilation within minispikes around intermediate-mass black holes (IMBHs) with masses ranging from 100~M_\odot to 106~M_\odot. When the thermal annihilation relic cross section ⟨ σv ⟩ = 3 × 10-26~\mathrm cm 3 \mathrm s -1 is adopted, we conduct an investigation on the population of IMBHs in the spherical halo area of M31. We find that there could be more than 65 IMBHs with masses of 100~ M_\odot surrounded by the DM minispikes as the remnants of Population III stars in the M31 spherical halo, and it is almost impossible for the existence of minspikes around IMBHs with masses above 104~ M_\odot which could be formed by the collapse of primordial cold gas, for both dark matter annihilation channels bb and τ+τ-. The properties of dark matter have been further explored with the simulation of these two scenarios for IMBHs formation.