Gravitational-wave cosmology with dark sirens: state of the art and perspectives for 3G detectors

TL;DR

This paper reviews how gravitational-wave observations of black hole mergers can constrain cosmological parameters and tests of gravity, discusses current methods, and explores future prospects with third-generation detectors using Fisher matrix analysis.

Contribution

It presents a comprehensive review of using binary black hole populations for cosmology and gravity tests, and evaluates future capabilities with 3G detectors employing Fisher matrix techniques.

Findings

Models with multiple features fit current data better.

Population studies suggest complex mass distributions.

Fisher matrix forecasts for 3G detectors show promising constraints.

Abstract

A joint fit of the mass and redshift distributions of the population of Binary Black Holes detected with Gravitational-Wave observations can be used to obtain constraints on the Hubble parameter and on deviations from General Relativity in the propagation of Gravitational Waves. We first present applications of this technique to the latest catalog of Gravitational-Wave events, focusing on the comparison of different parametrizations for the source-frame mass distribution of Black Hole Binaries. We find that models with more than one feature are favourite by the data, as suggested by population studies, even when varying the cosmology. Then, we discuss perspectives for the use of this technique with third generation Gravitational-Wave detectors, exploiting the recently developed Fisher information matrix Python code GWFAST.