A model-independent constraint on the Hubble constant with gravitational waves from the Einstein Telescope

TL;DR

This paper explores how future gravitational wave observations from the Einstein Telescope can precisely measure the Hubble constant without relying on specific cosmological models, using simulated data from binary neutron star mergers.

Contribution

It demonstrates the potential of third-generation gravitational wave detectors to constrain the Hubble constant independently of cosmological assumptions, with high precision from simulated data.

Findings

Hubble constant can be constrained to ~1% precision with 20 BNS mergers.

Additional GW sources improve the measurement accuracy.

Future GW measurements will outperform current constraints.

Abstract

In this paper, we investigate the expected constraints on the Hubble constant from the gravitational-wave standard sirens, in a cosmological-model-independent way. In the framework of the well-known Hubble law, the GW signal from each detected binary merger in the local universe ($z<0.10$) provides a measurement of luminosity distance $D_L$ and thus the Hubble constant $H_0$. Focusing on the simulated data of gravitational waves from the third-generation gravitational wave detector (the Einstein Telescope, ET), combined with the redshifts determined from electromagnetic counter parts and host galaxies, one can expect the Hubble constant to be constrained at the precision of $\sim 10^{-2}$ with 20 well-observed binary neutron star (BNS) mergers. Additional standard-siren measurements from other types of future gravitational-wave sources (NS-BH and BBH) will provide more precision constraints of this important cosmological parameter. Therefore, we obtain that future measurements of the luminosity distances of gravitational waves sources will be much more competitive than the current analysis, which makes it expectable more vigorous and convincing constraints on the Hubble constant in a cosmological-model-independent way.