Clustering Properties of Dynamical Dark Energy Models

TL;DR

This paper analyzes the clustering behavior of dark energy models, showing that fluctuations are small on cosmological scales, challenging common approximations, and exploring coupled dark energy-dark matter scenarios.

Contribution

It provides a clear, physical discussion of dark energy clustering, critiques the homogeneous approximation, and examines coupled dark energy models.

Findings

Dark energy fluctuations are small on sub-Hubble scales.

Homogeneous approximation is generally unrealistic.

Coupled dark energy models exhibit distinct clustering properties.

Abstract

We provide a generic but physically clear discussion of the clustering properties of dark energy models. We explicitly show that in quintessence-type models the dark energy fluctuations, on scales smaller than the Hubble radius, are of the order of the perturbations to the Newtonian gravitational potential, hence necessarily small on cosmological scales. Moreover, comparable fluctuations are associated with different gauge choices. We also demonstrate that the often used homogeneous approximation is unrealistic, and that the so-called dark energy mutation is a trivial artifact of an effective, single fluid description. Finally, we discuss the particular case where the dark energy fluid is coupled to dark matter.