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

TL;DR

This paper highlights potential biases in gravitational wave-based measurements of the universe's expansion due to simplistic black hole mass models, emphasizing the need for more adaptable models to improve accuracy.

Contribution

It demonstrates that heuristic black hole mass models can bias Hubble constant estimates and advocates for more flexible models in future GW cosmology research.

Findings

Biases up to 3 sigma in Hubble constant estimates with 2000 GW detections

Heuristic mass models fail to account for redshift evolution and unexpected mass features

Flexible source mass models are necessary for accurate cosmological inferences

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.