Is there a dark side to golden dark sirens?*

The golden dark siren strategy for measuring the Hubble constant (H_0) relies on the unique host-galaxy identification associated with gravitational-wave (GW) events that are precisely localized in the sky. In this work, we explore the systematics incurred when measuring H_0 using this approach, with next-generation ground-based GW observatories. Employing real and mock galaxy catalogs, we assess the biases stemming from neglecting faint galaxies that potentially host GW mergers. We also probe if the clustering of galaxies in the catalogs can help relax the stringent sky-localization criteria for golden dark sirens and help increase viable events for H_0 determination.