Gravitational Wave Cosmology: Be Careful of the Black Hole Mass Spectrum

Abstract

Gravitational waves (GWs) from compact binary coalescences (CBCs) offer insights into the universe expansion. The spectral siren method, used without electromagnetic counterparts (EMC), infers cosmic expansion (Hubble constant) by relating detector and source frame masses of black hole (BH) mergers. However, heuristic mass models (broken power law, power law plus peak, multipeak) may introduce biases in the Hubble constant estimation, potentially up to 3 sigma with 2000 detected GW mergers. These biases stem from the models inability to consider redshift evolution and unexpected mass features. Future GW cosmology studies should employ adaptable source mass models to address these issues.

arXiv comment6 pages, 3 figures, contribution to the 2024 Very High Energy Phenomena in the Universe session of the 58th Rencontres de Moriond