Dark-siren Cosmology with Decihertz Gravitational-wave Detectors

TL;DR

This paper evaluates how decihertz gravitational-wave detectors, DO-Optimal and DECIGO, can precisely measure cosmological parameters like the Hubble constant using dark sirens, significantly aiding in resolving current cosmological tensions.

Contribution

It demonstrates the high potential of decihertz GW detectors to constrain cosmological parameters with unprecedented precision using simulated dark siren data.

Findings

DO-Optimal constrains H_0 with less than 0.23% uncertainty.

DECIGO constrains H_0 with less than 0.043% uncertainty.

DECIGO achieves under 7% uncertainty in multi-parameter cosmological estimation.

Abstract

Gravitational waves (GWs) originated from mergers of stellar-mass binary black holes (SBBHs) are considered as dark sirens in cosmology since they usually do not have electromagnetic counterparts. In order to study cosmos with these events, we not only need the luminosity distances extracted from GW signals, but also require the redshift information of sources via, say, matching GW sky localization with galaxy catalogs. Based on such a methodology, we explore how well decihertz GW detectors, DO-Optimal and DECIGO, can constrain cosmological parameters. Using Monte-Carlo simulated dark sirens, we find that DO-Optimal can constrain the Hubble parameter to ${\sigma_{H_0}} / {H_0}\, \lesssim 0.23\%$ when estimating $H_0$ alone, while DECIGO performs better by a factor of 5 with ${\sigma_{H_0}} / {H_0}\lesssim 0.043\%$. Such a good precision of $H_0$ will shed light on the $H_0$ tension. For multiple-parameter estimation, DECIGO can still reach a level of relative uncertainty smaller than $7\%$. The reason why decihertz detectors perform well is explained by their large numbers of SBBH GW events with good distance and angular resolution.