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 $1–100M_{\odot }$. 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.

• Received 29 August 2019
• Accepted 30 January 2020

DOI:https://doi.org/10.1103/PhysRevD.101.043015

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society