Voids and overdensities of coupled Dark Energy

TL;DR

This paper studies how dynamical Dark Energy clusters in the universe, especially when coupled with Dark Matter, revealing that it can form voids or overdensities and is generally nearly homogeneous.

Contribution

It explores the clustering behavior of coupled Dark Energy, showing its potential to form voids and overdensities, and finds that coupling suppresses Dark Energy fluctuations.

Findings

Dark Energy can form voids and overdensities within matter inhomogeneities.

Coupling with Dark Matter slightly suppresses Dark Energy fluctuations.

Perturbation amplitudes are very small, indicating an almost homogeneous Dark Energy component.

Abstract

We investigate the clustering properties of dynamical Dark Energy even in association of a possible coupling between Dark Energy and Dark Matter. We find that within matter inhomogeneities, Dark Energy migth form voids as well as overdensity depending on how its background energy density evolves. Consequently and contrarily to what expected, Dark Energy fluctuations are found to be slightly suppressed if a coupling with Dark Matter is permitted. When considering density contrasts and scales typical of superclusters, voids and supervoids, perturbations amplitudes range from $|\delta_\phi|\sim {\cal O} (10^{-6})$ to $|\delta_\phi|\sim {\cal O} (10^{-4})$ indicating an almost homogeneous Dark Energy component.