Detecting Dark Energy Fluctuations with Gravitational Waves

TL;DR

This paper proposes a method to detect dark energy fluctuations using gravitational wave observations, which could provide direct evidence of dark energy inhomogeneities and test modifications to gravity.

Contribution

It introduces a novel joint estimator combining supernovae and gravitational wave data to directly measure dark energy fluctuations and probe the running of the Planck mass.

Findings

The estimator can detect dark energy fluctuations if they exist.

It provides a way to test theories beyond standard cosmology.

Experimental requirements for detection are discussed.

Abstract

Luminosity distance estimates from electromagnetic and gravitational wave sources are generally different in models of dynamical dark energy and gravity beyond the standard cosmological scenario. We show that this leaves a unique imprint on the angular power-spectrum of fluctuations of the luminosity distance of gravitational-wave observations which tracks inhomogeneities in the dark energy field. Exploiting the synergy in supernovae and gravitational wave distance measurements, we build a joint estimator that directly probes dark energy fluctuations, providing a conclusive evidence for their existence in case of detection. Moreover, such measurement would also allow to probe the running of the Planck mass. We discuss experimental requirements to detect these signals.