Tracing the redshift evolution of Hubble parameter with gravitational-wave standard sirens

TL;DR

This paper demonstrates that future space-based gravitational-wave detectors can directly measure the Hubble parameter's evolution with redshift using neutron-star binaries, achieving high precision up to z=1.

Contribution

It introduces a method to measure the Hubble parameter directly from monopole and dipole components of luminosity distances using gravitational-wave standard sirens.

Findings

Measurement accuracy of Hubble parameter improves with observation time.

High precision (0.8-14%) in H(z) measurement up to redshift 1.

Potential to probe cosmological expansion at high redshift.

Abstract

Proposed space-based gravitational-wave detectors such as BBO and DECIGO can detect ~10^6 neutron-star binaries and determine luminosity distance to the binaries with a high precision. Combining the luminosity distance and electromagnetically-derived redshift, one would be able to probe cosmological expansion out to high redshift. In this paper, we show that the Hubble parameter as a function of redshift can be directly measured with monopole and dipole components of the luminosity distance on the sky. As a result, the measurement accuracies of the Hubble parameter in each redshift bin up to z=1 are 3-14 %, 1.5-8 %, and 0.8-4% for the observation time 1 yr, 3 yr, and 10 yr, respectively.