Lower bound on the primordial black hole merger rate

TL;DR

This paper establishes a conservative lower bound on the primordial black hole merger rate, providing robust constraints on their abundance and highlighting the potential of LIGO/Virgo to detect PBHs across a wide mass range.

Contribution

It introduces a new lower bound on PBH merger rates based on perturbed binaries, improving constraints on PBH abundance and their spatial distribution.

Findings

Derived a lower bound on PBH merger rate from perturbed binaries.

Constraints on PBH abundance in the 1-100 M_sun range.

LIGO/Virgo sensitivity can probe PBHs from 10^-2 to 10^3 M_sun.

Abstract

We derive a lower bound on the merger rate of primordial black hole (PBH) binaries by estimating the maximal fraction of binaries that were perturbed between formation in the early Universe and merger, and computing a conservative merger rate of perturbed binaries. This implies robust constraints on the PBH abundance in the range $1-100 M_\odot$. We further show that LIGO/Virgo design sensitivity has the potential to reach the PBH mass range of $10^{-2}-10^3 M_\odot$. The constraint from the merger rate of perturbed binaries is stronger if PBHs are initially spatially clustered.