Systematic bias in dark siren statistical methods and its impact on Hubble constant measurement (2503.18887v1)

Abstract: The advent of the multimessenger cosmology marked by the detection of GW170817, gravitational waves from compact objects at cosmological distances demonstrated Standard Sirens as a relevant cosmological probe. In the absence of an electromagnetic counterpart identification, GWs carry valuable information through the dark siren approach, where the source redshift is estimated using galaxy catalogs of potential hosts within the localization volume. However, the dark siren analysis can be affected by galaxy catalog incompleteness at the limits of gravitational-wave detectability, potentially introducing biases in the constraints on cosmological parameters. Focusing on GWs from binary black holes detected by the LIGO, Virgo, and KAGRA collaboration, we explore the possible systematic biases in the measurement of the Hubble constant. These biases may arise from 1) the incompleteness of catalogs due to the apparent magnitude thresholds of optical telescope sensitivity, and 2) the use of incorrect weighting schemes (using star formation or stellar mass as tracers of the host galaxy) for each potential host. We found that an unbiased estimate of $H_0$ can be obtained when the corrected weighting scheme is applied to a complete or volume-limited catalog. The results using stellar mass as a tracer indicate that a percent-level measurement of $H_0$, with a precision of approximately 3%, can be achieved with 100 binary black hole detections by the LVK at O4 and O5 sensitivity. The O5 run provides a slight improvement, reducing the $H_0$ uncertainty by 0.07 km/s/Mpc compared to the O4-like configuration. This precision is achievable by using a complete galaxy catalog that covers the 90% of the localisation probability for each GW detection, with A$_{90\%}$<10 deg$^2$. The $H_0$ precision increases to approximately 6% when it is assumed that every galaxy has an equal probability of being the host.