Measuring the Hubble constant with black sirens

TL;DR

This paper proposes a statistical method to measure the Hubble constant using gravitational wave detections of binary black holes without electromagnetic counterparts, leveraging source distribution models and large datasets from future detectors.

Contribution

It introduces a novel approach to determine the Hubble constant solely from gravitational wave data, avoiding reliance on electromagnetic counterparts or galaxy catalogs.

Findings

Potential to constrain Hubble constant to percent level with future detectors.

Method effective with tens of thousands of black hole merger detections.

Does not depend on electromagnetic counterparts or galaxy catalog completeness.

Abstract

We investigate a recently proposed method for measuring the Hubble constant from gravitational wave detections of binary black hole coalescences without electromagnetic counterparts. In the absence of a direct redshift measurement, the missing information on the left-hand side of the Hubble-Lema\^itre law is provided by the statistical knowledge on the redshift distribution of sources. We assume that source distribution in redshift depends on unknown hyperparameters, modeling our ignorance of the astrophysical binary black hole distribution. With tens of thousands of these "black sirens" -- a realistic figure for the third generation detectors Einstein Telescope and Cosmic Explorer -- an observational constraint on the value of the Hubble parameter at percent level can be obtained. This method has the advantage of not relying on electromagnetic counterparts, which accompany a very small fraction of gravitational wave detections, nor on often unavailable or incomplete galaxy catalogs.