Gravitational wave background as a probe of the primordial black hole abundance

TL;DR

This paper explores how gravitational wave background measurements can constrain the abundance of primordial black holes across different mass ranges, linking cosmological density fluctuations to observational data.

Contribution

It demonstrates the potential of pulsar timing and space-based interferometers to detect or rule out primordial black holes of various masses based on gravitational wave signals.

Findings

Pulsar timing can detect primordial black holes around 100 solar masses.

Future space-based interferometers could probe black holes with masses 10^{20-26} g.

Gravitational wave background is a key probe for primordial black hole abundance.

Abstract

Formation of significant number of primordial black holes (PBHs) is realized if and only if primordial density fluctuations have a large amplitude, which means that tensor perturbations generated from these scalar perturbations as a second order effect are also large and comparable to the observational data. We show that pulsar timing observation could find/rule out PBHs with \sim 10^2 M_solar which are considered as a candidate of intermediate-mass black holes and that PBHs with mass range 10^{20-26} g, which serves as a candidate of dark matter, may be probed by future space-based laser interferometers and atomic interferometers.