Stochastic Gravitational-Wave Background due to Primordial Binary Black Hole Mergers

TL;DR

This paper calculates the gravitational-wave background from primordial binary black holes, compares it to stellar-origin black holes, and explores how future detectors could use this to constrain dark matter in black holes.

Contribution

It provides the first detailed computation of the stochastic gravitational-wave background from primordial black hole mergers and assesses its detectability and implications for dark matter.

Findings

Primordial black hole background could be detectable with future detectors.

The stochastic background can help constrain the fraction of dark matter in black holes.

Comparison shows differences between primordial and stellar black hole backgrounds.

Abstract

Recent Advanced LIGO detections of binary black hole mergers have prompted multiple studies investigating the possibility that the heavy GW150914 binary system was of primordial origin, and hence could be evidence for dark matter in the form of black holes. We compute the stochastic background arising from the incoherent superposition of such primordial binary black hole systems in the universe and compare it to the similar background spectrum due to binary black hole systems of stellar origin. We investigate the possibility of detecting this background with future gravitational wave detectors, and discuss the possibility of using the stochastic gravitational-wave background measurement to constrain the dark matter component in the form of black holes.