Dark-siren cosmology with decihertz gravitational-wave detectors
Published:
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 σ_{H_0}/H_0 ≲ 0.23% when estimating H0 alone, while DECIGO performs better by a factor of 5 with σ_{H_0}/H_0 ≲ 0.043%. Such a good precision of H0 will shed light on the H0 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.