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, $H_0$. Employing gravitational-wave observations from the Third Gravitational-Wave Transient Catalogue in conjunction with the GLADE+ galaxy catalogue, we show that restricting to bright galaxy subsets can enhance the precision of the $H_0$ estimate by up to 80 per cent 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 and luminous red galaxies – in gravitational-wave cosmology, particularly at redshifts where conventional galaxy catalogues offer limited coverage.