Dark standard siren cosmology with bright galaxy subsets

Abstract In this short paper, we investigate the impact of selecting only a subset of bright galaxies to provide redshift information for a dark standard siren measurement of the Hubble constant H0. Employing gravitational-wave observations from the Third Gravitational-Wave Transient Catalogue (GWTC-3) in conjunction with the GLADE+ galaxy catalogue, we show that restricting to bright galaxy subsets can enhance the precision of the H0 estimate by up to 80 % in the most favourable scenario. A comprehensive assessment of systematic uncertainties is still required. This work lays the foundation for employing alternative tracers — such as brightest cluster galaxies (BCGs) and luminous red galaxies (LRGs) — in gravitational-wave cosmology, particularly at redshifts where conventional galaxy catalogues offer limited coverage.