Constraining early and interacting dark energy with gravitational wave standard sirens: the potential of the eLISA mission

TL;DR

This study forecasts how the eLISA gravitational wave observatory can constrain early and interacting dark energy models by analyzing standard sirens from black hole mergers, highlighting its potential and limitations compared to other cosmological probes.

Contribution

It provides the first detailed forecast of eLISA's ability to constrain early and interacting dark energy models using simulated gravitational wave standard sirens.

Findings

eLISA can constrain dark energy models at redshifts 1 to 8.

eLISA is competitive for late-time deviations from ΛCDM.

Current probes outperform eLISA for pre-recombination dark energy models.

Abstract

We perform a forecast analysis of the capability of the eLISA space-based interferometer to constrain models of early and interacting dark energy using gravitational wave standard sirens. We employ simulated catalogues of standard sirens given by merging massive black hole binaries visible by eLISA, with an electromagnetic counterpart detectable by future telescopes. We consider three-arms mission designs with arm length of 1, 2 and 5 million km, 5 years of mission duration and the best-level low frequency noise as recently tested by the LISA Pathfinder. Standard sirens with eLISA give access to an intermediate range of redshift $1\lesssim z \lesssim 8$, and can therefore provide competitive constraints on models where the onset of the deviation from $\Lambda$CDM (i.e. the epoch when early dark energy starts to be non-negligible, or when the interaction with dark matter begins) occurs relatively late, at $z\lesssim 6$. If instead early or interacting dark energy is relevant already in the pre-recombination era, current cosmological probes (especially the cosmic microwave background) are more efficient than eLISA in constraining these models, except possibly in the interacting dark energy model if the energy exchange is proportional to the energy density of dark energy.