Forecasts for ΛCDM and Dark Energy Models through Einstein Telescope Standard Sirens

Abstract

Gravitational wave (GW) astronomy provides an independent way to estimate cosmological parameters. The detection of GWs from a coalescing binary allows a direct measurement of its luminosity distance, so these sources are referred to as “standard sirens” in analogy to standard candles. We investigate the impact of constraining cosmological models on the Einstein Telescope, a third-generation detector which will detect tens of thousands of binary neutron stars. We focus on non-flat ΛCDM cosmology and some dark energy models that may resolve the so-called Hubble tension. To evaluate the accuracy down to which ET will constrain cosmological parameters, we consider two types of mock datasets depending on whether or not a short gamma-ray burst is detected and associated with the gravitational wave event using the THESEUS satellite. Depending on the mock dataset, different statistical estimators are applied: one assumes that the redshift is known, and another marginalizes it, taking a specific prior distribution.

Keywords

• cosmological parameters
• gravitational waves
• neutron star mergers
• Einstein Telescope