Evolution of density and velocity profiles of dark matter and dark energy in spherical voids

TL;DR

This study models the evolution of density and velocity profiles of dark matter and dark energy within spherical cosmic voids, revealing how these profiles depend on dark energy parameters and initial conditions.

Contribution

It provides a numerical analysis of perturbation evolution in a multi-component universe, incorporating dark energy effects with varying equation-of-state and sound speed.

Findings

Matter density and velocity amplitudes vary by 4-7% with dark energy equation-of-state parameter w.

Profiles are minimally affected (about 1%) by changes in dark energy sound speed.

Results help understand the impact of dark energy properties on cosmic void evolution.

Abstract

We analyse the evolution of cosmological perturbations which leads to the formation of large isolated voids in the Universe. We assume that initial perturbations are spherical and all components of the Universe (radiation, matter and dark energy) are continuous media with perfect fluid energy--momentum tensors, which interact only gravitationally. Equations of the evolution of perturbations for every component in the comoving to cosmological background reference frame are obtained from equations of energy and momentum conservation and Einstein's ones and are integrated numerically. Initial conditions are set at the early stage of evolution in the radiation-dominated epoch, when the scale of perturbation is much larger than the particle horizon. Results show how the profiles of density and velocity of matter and dark energy are formed and how they depend on parameters of dark energy and initial conditions. In particular, it is shown that final matter density and velocity amplitudes change within range $\sim$4-7\% when the value of equation-of-state parameter of dark energy $w$ vary in the range from --0.8 to --1.2, and change within $\sim$1\% only when the value of effective sound speed of dark energy vary over all allowable range of its values.