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