Measurement of Hubble constant with stellar-mass binary black holes

TL;DR

This paper proposes a method to measure the Hubble constant using a small subset of binary black hole mergers with precisely localized sky positions, enabling redshift determination and high-precision cosmological measurements.

Contribution

It introduces a novel approach leveraging GW detections with small localization volumes to accurately determine the Hubble constant independently of other methods.

Findings

Hubble constant can be measured with better than 1% precision using this method.

A small number of BBH events with precise localization are sufficient for accurate measurement.

This approach offers an independent way to resolve the Hubble constant discrepancy.

Abstract

The direct detections of gravitational waves (GW) from merging binary black holes (BBH) by aLIGO have brought us a new opportunity to utilize BBH for a measurement of the Hubble constant. In this paper, we point out that there exists a small number of BBH that gives significantly small sky localization volume so that a host galaxy is uniquely identified. Then a redshift of a BBH is obtained from a spectroscopic follow-up observation of the host galaxy. Using these redshift-identified BBH, we show that the Hubble constant is measured at a level of precision better than 1% with advanced detectors like aLIGO at design sensitivity. Since a GW observation is completely independent of other astrophysical means, this qualitatively new probe will help resolve a well-known value discrepancy problem on the Hubble constant from cosmological measurements and local measurements.