# Stochastic background of gravitational waves generated by pre-galactic black holes

## TL;DR

This paper models the stochastic gravitational wave background from pre-galactic black holes formed by early stars, predicting signals that could be detectable by future advanced interferometers, providing insights into early universe structure formation.

## Contribution

It introduces a hierarchical structure formation model to estimate the gravitational wave background from pre-galactic black holes, linking star formation history with gravitational wave detectability.

## Key findings

- Predicted gravitational wave signals are below current detector sensitivity but detectable by next-generation interferometers.
- Correlation of advanced LIGO detectors could achieve high S/N ratios for signals from early star formation.
- Future detectors like EGO could detect signals with lower efficiency, enabling astrophysical insights.

## Abstract

In this work, we consider the stochastic background of gravitational waves (SBGWs) produced by pre-galactic stars, which form black holes in scenarios of structure formation. The calculation is performed in the framework of hierarchical structure formation using a Press-Schechter-like formalism. Our model reproduces the observed star formation rate at redshifts z < 6.5. The signal predicted in this work is below the sensitivity of the first generation of detectors but could be detectable by the next generation of ground-based interferometers. Specifically, correlating two coincident advanced LIGO detectors (LIGO III interferometers), the expected signal-to-noise-ratio (S/N) could be as high as 90 (10) for stars forming at redshift z ~ 20 with a Salpeter initial mass function with slope x=0.35 (1.35), and if the efficiency of generation of gravitational waves is close to the maximum value ~ 7 x 10^{-4}. However, the sensitivity of the future third generation of detectors as, for example, the European antenna EGO could be high enough to produce (S/N)}>3 same with efficiency ~ 2 x 10^{-5}. We also discuss what astrophysical information could be derived from a positive (or even negative) detection of the SBGWs investigated here.