Reconciling CMB and structure growth measurements with dark energy interactions

TL;DR

This paper investigates a coupled quintessence model with momentum exchange that can reconcile discrepancies between CMB and structure growth data, showing it fits observations as well as ΛCDM and is favored when cluster data is included.

Contribution

It introduces a coupled quintessence model with pure momentum exchange that addresses tensions in cosmological data and demonstrates improved fit with cluster observations.

Findings

Model suppresses structure growth for negative coupling values.

Model fits CMB and BAO data as well as ΛCDM.

Including cluster data favors the model, reducing χ² by over 16.

Abstract

We study a coupled quintessence model with pure momentum exchange and present the effects of such an interaction on the Cosmic Microwave Background (CMB) and matter power spectrum. For a wide range of negative values of the coupling parameter $\beta$ structure growth is suppressed and the model can reconcile the tension between Cosmic Microwave Background observations and structure growth inferred from cluster counts. We find that this model is as good as $\Lambda$CDM for CMB and baryon acoustic oscillation (BAO) data, while the addition of cluster data makes the model strongly preferred, improving the best-fit $\chi^2$-value by more than $16$.