Measuring the Hubble constant using strongly lensed gravitational wave signals

The measurement of the Hubble constant H-0 plays an important role in the study of cosmology. In this work, we propose a new method to constrain the Hubble constant using the strongly lensed gravitational wave (SLGW) signals. Through reparameterization, we find that the lensed waveform is sensitive to the H-0. Assuming the scenario that no electromagnetic counterpart of the GW source can be identified, our method can still give meaningful constraints on the H-0 with the information of the lens redshift. We then apply Fisher information matrix and Markov Chain Monte Carlo to evaluate the potential of this method. For the space-based GW detector, TianQin, the H-0 can be constrained within a relative error of similar to 1% with a single SLGW event.

Automated summary

This work proposes a new method to constrain the Hubble constant using strongly lensed gravitational wave (SLGW) signals. The lensed waveform is found to be sensitive to H-0 through reparameterization. Even in scenarios where no electromagnetic counterpart of the GW source can be identified, meaningful constraints on H-0 can still be obtained using the information of the lens redshift. The potential of this method is evaluated using Fisher information matrix and Markov Chain Monte Carlo, and it is found that the H-0 can be constrained within a relative error of about 1% with a single SLGW event for the space-based GW detector TianQin.