Gravitational wave backgrounds and the cosmic transition from Population III to Population II stars

TL;DR

This paper models the evolution of gravitational wave backgrounds from Population III and II stars, assessing their potential as foregrounds for primordial signals in upcoming gravitational wave detectors.

Contribution

It introduces a comprehensive simulation-based prediction of gravitational wave backgrounds from early stars, linking stellar evolution to observable gravitational signals.

Findings

Predicted gravitational wave backgrounds from Population III and II stars.

Compared background amplitudes with detector sensitivities.

Assessed potential interference with inflationary gravitational wave signals.

Abstract

Using the results of a numerical simulation which follows the evolution, metal enrichment and energy deposition of both Population III and Population II stars, we predict the redshift dependence of the formation rate of black hole remnants of Population III stars with masses 100- 500Msun and of neutron stars(black holes) remnants of Population II stars with masses 8-20Msun (20-40Msun). We describe the gravitational wave spectrum produced by Population III and Population II sources adopting the most appropriate signals available in the literature and we compute the stochastic backgrounds resulting from the cumulative emission of these sources throughout the history of the Universe. With the aim of assessing whether these backgrounds might act as foregrounds for signals generated in the Inflationary epoch, we compare their amplitudes with the sensitivity of currently planned and future ground/space-based interferometers.