Boosted dark matter from primordial black holes produced in a first-order phase transition

TL;DR

This paper explores how a first-order phase transition in a dark sector can produce primordial black holes from fermionic dark matter, leading to detectable signals in dark matter experiments, gravitational wave observatories, and CMB measurements.

Contribution

It introduces a novel mechanism linking dark sector phase transitions to primordial black hole formation and associated observable signals across multiple experiments.

Findings

Primordial black holes can form from dark matter during a phase transition.

Evaporating PBHs produce a boosted dark matter flux detectable in experiments.

Gravitational wave signals correlate with dark matter and cosmological observations.

Abstract

During a cosmological first-order phase transition in a dark sector, fermion dark matter particles $\chi$ can form macroscopic Fermi balls that collapse to primordial black holes (PBHs) under certain conditions. The evaporation of the PBHs produces a boosted $\chi$ flux, which may be detectable if $\chi$ couples to visible matter. We consider the interaction of $\chi$ with electrons, and calculate signals of the dark matter flux in the XENON1T, XENONnT, Super-Kamiokande and Hyper-Kamiokande experiments. A correlated gravitational wave signal from the phase transition can be observed at THEIA and $\mu$Ares. An amount of dark radiation measurable by CMB-S4 is an epiphenomenon of the phase transition.