Effect of metallicity on the gravitational-wave signal from the cosmological population of compact binary coalescences

TL;DR

This study investigates how metallicity influences the gravitational-wave background from extragalactic compact binaries, revealing that metallicity affects the spectrum's peak and that the background is mainly from binary black holes detectable by current and future detectors.

Contribution

It introduces models linking metallicity to gravitational-wave background predictions, highlighting the impact of stellar environment properties on gravitational-wave signals.

Findings

Background dominated by binary black holes across models

Detectability of the background with advanced detectors

Metallicity influences the spectral peak of gravitational waves

Abstract

Recent studies on stellar evolution have shown that the properties of compact objects strongly depend on the metallicity of the environment in which they were formed. Using some very simple assumptions on the metallicity of the stellar populations, we explore how this property affects the unresolved gravitational-wave background from extragalactic compact binaries. We obtained a suit of models using population synthesis code, estimated the gravitational-wave background they produce, and discuss its detectability with second- (advanced LIGO, advanced Virgo) and third- (Einstein Telescope) generation detectors. Our results show that the background is dominated by binary black holes for all considered models in the frequency range of terrestrial detectors, and that it could be detected in most cases by advanced LIGO/Virgo, and with Einstein Telescope with a very high signal-to-noise ratio. The observed peak in a gravitational wave spectrum depends on the metallicity of the stellar population.