Gravitational waves from burdened primordial black holes dark matter

TL;DR

This paper explores how quantum effects can extend the lifetime of primordial black holes, allowing them to be dark matter candidates, and predicts associated gravitational wave signals from their formation.

Contribution

It introduces a quantum memory burden effect that suppresses PBH evaporation, opening a new mass window for PBM as dark matter and analyzes their gravitational wave signatures.

Findings

Quantum memory burden can significantly delay PBH evaporation.

Distinct gravitational wave signatures are predicted for different PBH formation scenarios.

Future GW detectors could potentially observe these signals.

Abstract

Primordial black holes (PBHs) are the natural candidate of dark matter (DM) as they only interact gravitationally and can evade any experiments on earth. In the standard semiclassical calculation of Hawking radiation, PBHs with mass below $10^{15}\rm g$ evaporated by now and therefore cannot be DM. However, the recently-discovered quantum memory burden effect can significantly suppress the evaporation of PBHs after the half-decay time. This quantum effect could open up a new mass window below $10^{10} \rm g$ where PBHs can still exist today and be DM. In this paper, we compute the gravitational wave (GW) signals associated with the formation of PBHs in this new mass window. We consider two formation scenarios: PBHs formed from inflationary perturbation and PBHs formed from collapse of Fermi-balls in a first-order phase transition (FOPT). GWs produced from these two scenarios have distinct features and, while the GW from inflation peaks at high frequency, the GW from FOPT peaks at lower frequency that can be within the reach of future experiments.