Prospects of discovering sub-solar primordial black holes using the stochastic gravitational wave background from third-generation detectors

TL;DR

This paper explores how third-generation gravitational wave detectors can detect sub-solar mass primordial black holes through the stochastic gravitational wave background, enabling constraints on their abundance and formation scenarios.

Contribution

It demonstrates the potential of future detectors to identify sub-solar PBHs, distinguish their formation channels, and constrain their dark matter fraction with high precision.

Findings

Can constrain PBH dark matter fraction to ≤1% at 68% CL

Will measure PBH merger rate evolution with about 1% accuracy

Can distinguish between Poisson and clustered PBH scenarios

Abstract

Primordial black holes (PBHs) are dark matter candidates that span broad mass ranges from $10^{-17}$ $M_\odot$ to $\sim 100$ $M_\odot$. We show that the stochastic gravitational wave background can be a powerful window for the detection of sub-solar mass PBHs and shed light on their formation channel via third-generation gravitational wave detectors such as Cosmic Explorer and the Einstein Telescope. By using the mass distribution of the compact objects and the redshift evolution of the merger rates, we can distinguish astrophysical sources from PBHs and will be able to constrain the fraction of sub-solar mass PBHs $\leq 1$ $M_\odot$ in the form of dark matter $f_{PBH}\leq 1\%$ at $68\%$ C.L. even for a pessimistic value of a binary suppression factor. In the absence of any suppression of the merger rate, constraints on $f_{PBH}$ will be less than $0.001\%$. Furthermore, we will be able to measure the redshift evolution of the PBH merger rate with about $1\%$ accuracy, making it possible to uniquely distinguish between the Poisson and clustered PBH scenarios.