Dark energy and key physical parameters of clusters of galaxies

TL;DR

This paper explores how dark energy influences galaxy cluster physics, revealing that key cluster parameters are directly determined by dark energy under the cosmological constant model, affecting their structure and gravitational potential.

Contribution

It demonstrates that dark energy sets fundamental physical parameters of galaxy clusters, such as halo size and density, within the cosmological constant framework.

Findings

Halo cut-off radius equals the zero-gravity radius.

Halo average density is twice the dark energy density.

Halo edge density matches dark energy density.

Abstract

We study physics of clusters of galaxies embedded in the cosmic dark energy background. Under the assumption that dark energy is described by the cosmological constant, we show that the dynamical effects of dark energy are strong in clusters like the Virgo cluster. Specifically, the key physical parameters of the dark mater halos in clusters are determined by dark energy: 1) the halo cut-off radius is practically, if not exactly, equal to the zero-gravity radius at which the dark matter gravity is balanced by the dark energy antigravity; 2) the halo averaged density is equal to two densities of dark energy; 3) the halo edge (cut-off) density is the dark energy density with a numerical factor of the unity order slightly depending on the halo profile. The cluster gravitational potential well in which the particles of the dark halo (as well as galaxies and intracluster plasma) move is strongly affected by dark energy: the maximum of the potential is located at the zero-gravity radius of the cluster.