Constraining ?CDM cosmological parameters with Einstein Telescope mock data

We investigate the capability of Einstein Telescope to constrain the cosmological parameters of the non-flat lambda CDM cosmological model. Two types of mock data sets are considered depending on whether or not a short gamma-ray burst is detected, and associated with the gravitational wave emitted by binary neutron stars merger, using the THESEUS satellite. Depending on the mock data set, two statistical estimators are applied: one assumes that the redshift is known, while the other marginalizes o v er it assuming a specific redshift prior distribution. We demonstrate that (i) using mock catalogues collecting gravitational wave signals emitted by binary neutron stars systems to which a short gamma-ray burst has been associated, Einstein Telescope may achieve an accuracy on the cosmological parameters of sigma(H0) asymptotic to 0 . 40 km s(-1) Mpc -1, sigma(omega k,0) asymptotic to 0.09, and sigma(omega lambda,0) asymptotic to 0 . 07; while (ii) using mock catalogues collecting all gravitational wave signals emitted by binary neutron stars systems for which an electromagnetic counterpart has not been detected, Einstein Telescope may achieve an accuracy on the cosmological parameters of sigma(H0) asymptotic to 0 . 04 km s(-1) Mpc (-1), sigma(omega k,0) asymptotic to 0 . 01, and sigma(omega lambda,0) asymptotic to 0.01, once the redshift probability distribution of GW events is known from from population synthesis simulations and/or the measure of the tidal deformability parameter. These results show an impro v ement of a factor 2-75 with respect to earlier results using complementary data sets.

Automated summary

We investigate the capability of Einstein Telescope to constrain the cosmological parameters of the non-flat lambda CDM cosmological model. Two types of mock data sets are considered depending on whether or not a short gamma-ray burst is detected, and associated with the gravitational wave emitted by binary neutron stars merger, using the THESEUS satellite. The results show that Einstein Telescope can achieve high accuracy in constraining the cosmological parameters.