Constraints on primordial black holes in dSphs using radio observations

TL;DR

This paper uses radio observations of dwarf spheroidal galaxies to set new constraints on primordial black holes as dark matter candidates, employing synchrotron self-Compton effects and projecting improvements with future telescopes.

Contribution

It introduces a novel method using radio data and SSC effects to constrain PBH abundance in dwarf galaxies, achieving tighter bounds at certain mass ranges.

Findings

Constraints on PBH fraction down to ~10^{-3} for Segue I and ~10^{-5} for Fornax.

Future SKA observations could match the strictest current limits for PBHs below 5×10^{15} g.

Including inverse Compton scattering could further improve constraints.

Abstract

Primordial black holes (PBHs) are hypothetical objects formed at the early epoch of the universe, which could be a type of dark matter (DM) candidate without the need for new particles. The abundance of PBH DM has been constrained strictly by many observations.In this work, with the radio observations of Fornax and Segue I, we constrain the abundance of PBH in dwarf spheroidal galaxies through the synchrotron self-Compton (SSC) effect of Hawking radiation electrons. By selecting optimal sources, we obtain the constraints on the fraction of PBH DM down to $\sim10^{-3}$ for Segue I and $\sim10^{-5}$ for Fornax at asteroidal mass. We also predict that, with 100 hours of future observation by the Square Kilometer Array, the SSC approach could place constraints comparable to the current strictest results for PBHs of $<5\times10^{15}\,{\rm g}$. Better projected constraints can be obtained by including the inverse Compton scattering on cosmic microwave background photons.