Gravitational wave cosmology and astrophysics with large spectroscopic galaxy surveys

During the next decade, gravitational waves will be observed from hundreds of binary inspiral events. When the redshifts of the host galaxies are known, these events can be used as “standard sirens”, sensitive to the expansion rate of the Universe. Measurements of the Hubble constant H0 from standard sirens can be done independently of other cosmological probes, and events occurring at z < 0.1 will allow us to infer H0 independentently of cosmological models. The next generation of spectroscopic galaxy surveys will play a crucial role in reducing systematic uncertainties in H0 from standard sirens, particularly for the numerous “dark sirens” which do not have an electromagnetic counterpart. In combination with large spectroscopic data sets, standard sirens with an EM counterpart are expected to constrain H0 to ∼ 1 − 2% precision within the next decade. This is competitive with the best estimates of H0 obtained to date and will help illuminate the current tension between existing measurements.