Holographic dark energy described at the Hubble length

TL;DR

This paper explores holographic dark energy models with the Hubble radius as the infrared cutoff, demonstrating their equivalence to certain interacting models and constraining their parameters with observational data.

Contribution

It shows that interacting dark energy models with matter-like terms can be reformulated as noninteracting models with evolving holographic parameters, providing new insights into dark energy modeling.

Findings

Models can be distinguished at the perturbative level.

Both models fit observational data well.

Reformulation simplifies understanding dark energy dynamics.

Abstract

We consider holographic cosmological models of dark energy in which the infrared cutoff is set by the Hubble's radius. We show that any interacting dark energy model with a matter like term able to alleviate the coincidence problem (i.e., with a positive interaction term, regardless of its detailed form) can be recast as a noninteracting model in which the holographic parameter evolves slowly with time. Two specific cases are analyzed. First, the interacting model presented in [1] is considered, and its corresponding noninteracting version found. Then, a new noninteracting model, with a specific expression of the time-dependent holographic parameter, is proposed and analyzed along with its corresponding interacting version. We constrain the parameters of both models using observational data, and show that they can be told apart at the perturbative level.