Cosmological constraints on coupled dark energy

TL;DR

This paper investigates coupled dark energy models using various cosmological observations, finding no significant evidence of interaction between dark energy and dark matter at the 2σ level.

Contribution

The study derives evolution equations for coupled dark energy models and constrains them using multiple observational datasets, highlighting the difficulty in distinguishing these models from standard cosmology.

Findings

No evidence of dark energy-dark matter interaction at 2σ

Coupled models are hard to differentiate from standard models

Current data do not favor interaction in dark energy models

Abstract

The coupled dark energy model provides a possible approach to mitigate the coincidence problem of cosmological standard model. Here, the coupling term is assumed as $\bar{Q}=3H\xi_x\bar{\rho}_x$, which is related to the interaction rate and energy density of dark energy. We derive the background and perturbation evolution equations for several coupled models. Then, we test these models by currently available cosmic observations which include cosmic microwave background radiation from Planck 2015, baryon acoustic oscillation, type Ia supernovae, $f\sigma_8(z)$ data points from redshift-space distortions, and weak gravitational lensing. The constraint results tell us there is no evidence of interaction at 2$\sigma$ level, it is very hard to distinguish different coupled models from other ones.