Hubble parameter estimation via dark sirens with the LISA-Taiji network

TL;DR

This paper demonstrates that the LISA-Taiji space gravitational wave network can independently measure the Hubble parameter with sub-percent accuracy within five years, providing a crucial cosmological probe.

Contribution

It introduces a method to estimate the Hubble parameter using dark sirens from the LISA-Taiji network, achieving unprecedented precision in a model-independent way.

Findings

LISA-Taiji can constrain Hubble parameter within 1% accuracy in 5 years

The network could improve measurements to 0.5% or better

Gravitational wave observations provide an independent cosmological probe

Abstract

The Hubble parameter is one of the central parameters in modern cosmology, which describes the present expansion rate of the universe. Their values inferred from the late-time observations are systematically higher than those from the early-time measurements by about $10\%$. To come to a robust conclusion, independent probes with accuracy at percent levels are crucial. Gravitational waves from compact binary coalescence events can be formulated into the standard siren approach to provide an independent Hubble parameter measurement. The future space-borne gravitational wave observatory network, such as the LISA-Taiji network, will be able to measure the gravitational wave signals in the Millihertz bands with unprecedented accuracy. By including several statistical and instrumental noises, we show that within 5 years operation time, the LISA-Taiji network is able to constrain the Hubble parameter within $1\%$ accuracy, and possibly beats the scatters down to $0.5\%$ or even better.