Progress toward the detection of the gravitational-wave background from stellar-mass binary black holes: a mock data challenge

TL;DR

This paper demonstrates a more sensitive coherent search method for detecting the gravitational-wave background from stellar-mass binary black holes using realistic data, advancing the potential for future discoveries.

Contribution

It provides a practical implementation of the coherent search approach, highlighting its feasibility and benefits over traditional methods in realistic data scenarios.

Findings

Coherent search method improves sensitivity to gravitational-wave background.

Realistic data analysis confirms the method's practical applicability.

Sets the stage for future high-sensitivity gravitational-wave background searches.

Abstract

While the third LIGO--Virgo gravitational-wave transient catalog includes 90 signals, it is believed that ${\cal O}(10^5)$ binary black holes merge somewhere in the Universe every year. Although these signals are too weak to be detected individually with current observatories, they combine to create a stochastic background, which is potentially detectable in the near future. LIGO--Virgo searches for the gravitational-wave background using cross-correlation have so far yielded upper limits. However, Smith \& Thrane (2017) showed that a vastly more sensitive ``coherent'' search can be carried out by incorporating information about the phase evolution of binary black hole signals. This improved sensitivity comes at a cost; the coherent method is computationally expensive and requires a far more detailed understanding of systematic errors than is required for the cross-correlation search. In this work, we demonstrate the coherent approach with realistic data, paving the way for a gravitational-wave background search with unprecedented sensitivity.