Effect of Dark Energy Perturbation on Cosmic Voids Formation

TL;DR

This study investigates how dark energy perturbations influence the formation, size, and distribution of cosmic voids, revealing that while size evolution is minimally affected, void abundance varies significantly with dark energy parameters.

Contribution

It provides a detailed analysis of dark energy perturbation effects on cosmic voids, highlighting their impact on void size distribution and abundance across different dark energy models.

Findings

Dark energy perturbation negligibly affects void size evolution.

Void size distribution is highly sensitive to dark energy perturbations.

Large void abundance varies by up to 25% depending on dark energy parameters.

Abstract

In this paper, we present the effects of dark energy perturbation on the formation and abundance of cosmic voids. We consider dark energy to be a fluid with a negative pressure characterised by a constant equation of state w and speed of sound $c^2_s$. By solving fluid equations for two components, namely, dark matter and dark energy fluids, we quantify the effects of dark energy perturbation on the sizes of top-hat voids. We also explore the effects on the size distribution of voids based on the excursion set theory. We confirm that dark energy perturbation negligibly affects the size evolution of voids;$c^2_s = 0$ varies the size only by 0.1% as compared to the homogeneous dark energy model. We also confirm that dark energy perturbation suppresses the void size when w < -1 and enhances the void size when $w > -1$ (Basse et al. 2011). In contrast to the negligible impact on the size, we find that the size distribution function on scales larger than 10 Mpc/h highly depends on dark energy perturbation; compared to the homogeneous dark energy model, the number of large voids of radius 30Mpc is 25% larger for the model with $w = -0.9$ and $c^2_s = 0$ while they are 20% less abundant for the model with $w = -1.3$ and $c^2_s = 0$.