Probing Interacting Dark Sector with the next generation of gravitational-wave detectors

TL;DR

This paper evaluates the potential of next-generation gravitational-wave detectors to constrain models of an interacting dark sector, highlighting challenges due to parameter degeneracies and the benefits of external priors.

Contribution

It demonstrates the capability of third-generation GW detectors to probe dark sector interactions and analyzes how external priors can mitigate parameter degeneracies.

Findings

Degeneracies bias cosmological parameter estimation.

External priors on matter density improve dark sector parameter accuracy.

Third-generation GW detectors can effectively constrain interacting dark sector models.

Abstract

We have probed the capability of third-generation Gravitational Waves (GW) interferometers, such as the Einstein Telescope and Cosmic Explorer, to constrain a cosmological model with an interacting dark sector. We focused on GW events with a detected electromagnetic counterpart being the $\gamma$ or X emission of Gamma-Ray Burst, and a Kilonova emission. We assume the first one to be detected by the THESEUS satellite, while the second one to be detected by the Vera Rubin Observatory. We probed three different interaction kernels and found that the posterior estimation of the cosmological parameters is biased due to the existing degeneracies between the dark and matter sectors. We also found that introducing an external prior on the matter density parameter breaks the degeneracy, removes the bias results, and improves the accuracy on the dark sector parameters.