Constraining interacting dark energy with CMB and BAO future surveys

TL;DR

This study forecasts how future CMB and BAO surveys can tightly constrain interacting dark energy models, potentially ruling out or confirming dark sector interactions with high precision.

Contribution

It demonstrates that combining future CMB and BAO data can significantly improve constraints on interacting dark energy models, breaking parameter degeneracies and testing interaction hypotheses.

Findings

Combined CMB and BAO data can break parameter degeneracies.

Future surveys could exclude null interaction in some models.

Constraints vary across different dark energy interaction models.

Abstract

In this paper, we perform a forecast analysis to test the capacity of future baryon acoustic oscillation (BAO) and cosmic microwave background (CMB) experiments to constrain phenomenological interacting dark energy models using the Fisher matrix formalism. We consider a Euclid-like experiment, in which BAO measurements is one of the main goals, to constrain the cosmological parameters of alternative cosmological models. Moreover, additional experimental probes can more efficiently provide information on the parameters forecast, justifying also the inclusion in the analysis of a future ground-based CMB experiment mainly designed to measure the polarization signal with high precision. In the interacting dark energy scenario, a coupling between dark matter and dark energy modifies the conservation equations such that the fluid equations for both constituents are conserved as the total energy density of the dark sector. In this context, we consider three phenomenological models which have been deeply investigated in literature over the past years. We find that the combination of both CMB and BAO information can break degeneracies among the dark sector parameters for all three models, although to different extents. We found powerful constraints on, for example, the coupling constant when comparing it with present limits for two of the models, and their future statistical 3-$\sigma$ bounds could potentially exclude the null interaction for the combination of probes that is considered. However, for one of the models, the constraint on the coupling parameter does not improve the present result (achieved using a large combination of surveys), and a larger combination of probes appears to be necessary to eventually claim whether or not interaction is favored in that context.