Standard-siren cosmology using gravitational waves from binary black holes.- [PDF] - [Article]

Zhi-Qiang You, Xing-Jiang Zhu, Gregory Ashton, Eric Thrane, Zong-Hong Zhu

Gravitational-wave astronomy provides a unique new way to study the expansion history of the Universe. In this work, we investigate the impact future gravitational-wave observatories will have on cosmology. Third-generation observatories like the Einstein Telescope and Cosmic Explorer will be sensitive to essentially all of the binary black hole coalescence events in the Universe. Recent work by \cite{farr2019future} points out that features in the stellar-mass black hole population break the mass-redshift degeneracy, facilitating precise determination of the Hubble parameter without electromagnetic counterparts or host galaxy catalogues. Using a hierarchical Bayesian inference model, we show that with one year of observation by the Einstein Telescope, the Hubble constant will be measured to $\lesssim0.5\%$. We show that this method can be used to perform Bayesian model selection between cosmological models. As an illustrative example, we show that a decisive statement can be made comparing the $\Lambda$CDM and RHCT cosmic models using just one week of data from the Einstein Telescope.