Joint constraints on cosmological parameters using future multi-band gravitational wave standard siren observations

Gravitational waves (GWs) from the compact binary coalescences can be used as standard sirens to explore the cosmic expansion history. In the next decades, it is anticipated that we could obtain the multi-band GW standard siren data (from nanohertz to a few hundred hertz), which are expected to play an important role in cosmological parameter estimation. In this work, we give for the first time the joint constraints on cosmological parameters using the future multi-band GW standard siren observations. We simulate the multi-band GW standard sirens based on the SKA-era pulsar timing array (PTA), the Taiji observatory, and the Cosmic Explorer (CE) to perform cosmological analysis. In the Lambda CDM model, we find that the joint PTA+Taiji+CE data could provide a tight constraint on the Hubble constant with a 0.5% precision. Moreover, PTA+Taiji+CE could break the cosmological parameter degeneracies generated by CMB, especially in the dynamical dark energy models. When combining the PTA+Taiji+CE data with the CMB data, the constraint precisions of Omega(m) and H-0 are 1.0% and 0.3%, meeting the standard of precision cosmology. The joint CMB+PTA+Taiji+CE data give sigma(w)=0.028 in the wCDM model and sigma(w(0))=0.11 and sigma(w(a))=0.32 in the w(0)w(a)CDM model, which are comparable with or close to the latest constraint results by CMB+BAO+SN. In conclusion, it is worth expecting to use the future multi-band GW observations to explore the nature of dark energy and measure the Hubble constant.

Automated summary

Gravitational waves can be used to explore the cosmic expansion history, and future multi-band gravitational wave standard siren data are expected to play a significant role in cosmological parameter estimation.