Searching for Primordial Black Holes in the radio and X-ray sky

Abstract

We model the accretion of gas onto a population of massive primordial black holes in the Milky Way, and compare the predicted radio and X-ray emission with observational data. We show that under conservative assumptions on the accretion process, the possibility that ${\cal O}(10) \, M_\odot$ primordial black holes can account for all of the dark matter in the Milky Way is excluded at $5\sigma$ by a comparison with a VLA radio catalog at $1.4$ GHz, and at $\simeq 40\sigma$ by a comparison with a Chandra X-ray catalog ($0.5 - 8$ keV). We argue that this method can be used to identify such a population of primordial black holes with more sensitive future radio and X-ray surveys.