Correlated signals of first-order phase transitions and primordial black hole evaporation

TL;DR

This paper explores how first-order phase transitions in the early universe can produce primordial black holes and associated gravitational waves, which may be correlated with X-ray and gamma-ray backgrounds from black hole evaporation.

Contribution

It demonstrates the correlation between phase transition-generated primordial black holes, gravitational waves, and electromagnetic backgrounds, providing a multi-messenger approach to probe early universe physics.

Findings

Phase transitions produce PBHs with specific mass ranges.

Gravitational waves from phase transitions are detectable by future observatories.

X-ray and gamma-ray backgrounds can be linked to PBH evaporation.

Abstract

Fermi balls produced in a cosmological first-order phase transition may collapse to primordial black holes (PBHs) if the fermion dark matter particles that comprise them interact via a sufficiently strong Yukawa force. We show that phase transitions described by a quartic thermal effective potential with vacuum energy, $0.1\lesssim B^{1/4}/{\rm MeV} \lesssim 10^3$, generate PBHs of mass, $10^{-20}\lesssim M_{\rm PBH}/M_\odot \lesssim 10^{-16}$, and gravitational waves from the phase transition (at THEIA/$\mu$Ares) can be correlated with an isotropic extragalactic X-ray/$\gamma$-ray background from PBH evaporation (at AMEGO-X/e-ASTROGAM).