Evolution of density and velocity profiles of matter in large voids

TL;DR

This paper models the evolution of matter density and velocity profiles in large cosmic voids by simulating spherical perturbations in a multi-component universe, revealing how these profiles develop over time.

Contribution

It introduces a gravitationally interacting multi-component fluid model to simulate the formation of voids from early universe perturbations.

Findings

Density and velocity profiles of matter in voids are shaped by gravitational evolution.

Profiles depend on initial overdensity conditions.

The model captures the formation process of large cosmic voids.

Abstract

We analyse the evolution of cosmological perturbations which leads to the formation of large voids in the distribution of galaxies. We assume that perturbations are spherical and all components of the Universe - radiation, matter and dark energy - are continuous media with ideal fluid energy-momentum tensors, which interact only gravitationally. Equations of the evolution of perturbations in the comoving to cosmological background reference frame for every component are obtained from equations of conservation and Einstein's ones and are integrated by modified Euler method. Initial conditions are set at the early stage of evolution in the radiation-dominated epoch, when the scale of perturbation is mush larger than the particle horizon. Results show how the profiles of density and velocity of matter in spherical voids with different overdensity shells are formed.