Stochastic Gravitational-Wave Background from Binary Black Holes and Binary Neutron Stars and Implications for LISA

TL;DR

This paper calculates the stochastic gravitational-wave background from binary black holes and neutron stars, highlighting the stronger contribution from primordial black holes and implications for detection by LIGO/Virgo and LISA.

Contribution

It provides a comparative analysis of astrophysical and primordial black hole scenarios for the SGWB and assesses their impact on future gravitational wave observations.

Findings

PBHs contribute a stronger SGWB than stellar-origin black holes.

The combined SGWB may be detectable by LIGO/Virgo and LISA.

SGWB acts as confusion noise, reducing LISA's detection sensitivity for other sources.

Abstract

The advent of gravitational wave (GW) and multi-messenger astronomy has stimulated the research on the formation mechanisms of binary black holes (BBHs) observed by LIGO/Virgo. In literature, the progenitors of these BBHs could be stellar-origin black holes (sBHs) or primordial black holes (PBHs). In this paper we calculate the Stochastic Gravitational-Wave Background (SGWB) from BBHs, covering the astrophysical and primordial scenarios separately, together with the one from binary neutron stars (BNSs). Our results indicate that PBHs contribute a stronger SGWB than that from sBHs, and the total SGWB from both BBHs and BNSs has a high possibility to be detected by the future observing runs of LIGO/Virgo and LISA. On the other hand, the SGWB from BBHs and BNSs also contributes an additional source of confusion noise to LISA's total noise curve, and then weakens LISA's detection abilities. For instance, the detection of massive black hole binary (MBHB) coalescences is one of the key missions of LISA, and the largest detectable redshift of MBHB mergers can be significantly reduced.