Cross-correlation of the astrophysical gravitational-wave background with galaxy clustering

TL;DR

This paper explores how the gravitational-wave background correlates with galaxy distributions, revealing that cross-correlation on linear scales can constrain the background's evolution and serve as a tool for cosmology and merger physics.

Contribution

It demonstrates that cross-correlation with galaxy catalogs depends only on linear scales, enabling constraints on the gravitational-wave background's evolution over time.

Findings

Cross-correlation depends only on linear scales.

Constraints on the gravitational-wave background are feasible with galaxy surveys.

The method can probe both merger physics and cosmological parameters.

Abstract

We investigate the correlation between the distribution of galaxies and the predicted gravitational-wave background of astrophysical origin. We show that the large angular scale anisotropies of this background are dominated by nearby non-linear structure, which depends on the notoriously hard to model galaxy power spectrum at small scales. In contrast, we report that the cross-correlation of this signal with galaxy catalogues depends only on linear scales and can be used to constrain the average contribution to the gravitational-wave background as a function of time. Using mock data based on a simplified model, we explore the effects of galaxy bias, angular resolution and the matter abundance on these constraints. Our results suggest that, when combined with galaxy surveys, the gravitational-wave background can be a powerful probe for both gravitational-wave merger physics and cosmology.