# Listening to the sound of dark sector interactions with gravitational wave standard sirens

## TL;DR

This paper investigates how future gravitational wave observations can significantly improve constraints on dark matter-dark energy interactions, potentially detecting such interactions with high significance.

## Contribution

It demonstrates that gravitational wave standard sirens can enhance current limits on dark sector interactions and help identify them if they exist.

## Key findings

- Gravitational wave data can reduce uncertainty in interaction strength by a factor of 5.
- GW data can distinguish interacting dark sector models from non-interacting ones at over 3σ significance.
- Forecasts show potential to detect dark sector interactions with upcoming GW observations.

## Abstract

We consider two stable Interacting Dark Matter -- Dark Energy models and confront them against current Cosmic Microwave Background data from the \textit{Planck} satellite. We then generate luminosity distance measurements from ${\cal O}(10^3)$ mock Gravitational Wave events matching the expected sensitivity of the proposed Einstein Telescope. We use these to forecast how the addition of Gravitational Wave standard sirens data can improve current limits on the Dark Matter -- Dark Energy coupling strength ($\xi$). We find that the addition of Gravitational Waves data can reduce the current uncertainty by a factor of $5$. Moreover, if the underlying cosmological model truly features Dark Matter -- Dark Energy interactions with a value of $\xi$ within the currently allowed $1\sigma$ upper limit, the addition of Gravitational Wave data would help disentangle such an interaction from the standard case of no interaction at a significance of more than $3\sigma$.