Galaxy clusters in presence of dark energy: a kinetic approach

TL;DR

This paper develops a kinetic model to understand how dark energy influences the equilibrium structure of galaxy clusters, revealing that dark energy can prevent equilibrium configurations in certain conditions.

Contribution

It introduces a kinetic approach to analyze galaxy cluster equilibrium considering dark energy, extending previous models that mainly used gravitational or Newtonian frameworks.

Findings

Dark energy affects the gravitational equilibrium, making clusters more extended.

Certain parameter regions do not permit equilibrium due to dark energy dominance.

The model identifies conditions where dark energy prevents stable cluster configurations.

Abstract

Context. The external regions of galaxy clusters may be under strong influence of the dark energy, discovered by observations of the SN Ia at redshift z < 1. Aims. The presence of the dark energy in the gravitational equilibrium equation, with the Einstein $\Lambda$ term, contrasts the gravity, making the equilibrium configuration more extended in radius. Methods. In this paper we derive and solve the kinetic equation for an equilibrium configuration in presence of the dark energy, by considering the Newtonian regime, being the observed velocities of the galaxies inside a cluster largely smaller than the light velocity. Results. The presence of the dark energy in the gravitational equilibrium equation leads to wide regions in the $W_0-\rho_{\Lambda}$ diagram where the equilibrium solutions are not permitted, due to the prevalence of the effects of the dark energy on the gravity.