Angular momentum in cluster Spherical Collapse Model

TL;DR

This paper introduces an enhanced Spherical Collapse Model that incorporates angular momentum to better describe galaxy cluster dynamics, especially in non-equilibrium regions, aligning well with observations and simulations.

Contribution

The paper presents a new formulation of the Spherical Collapse Model including angular momentum, improving predictions of cluster velocity profiles and mass distribution.

Findings

Model accurately predicts galaxy velocities and mass profiles.

Results agree with recent observational data.

Enhanced model captures non-equilibrium cluster dynamics.

Abstract

Our new formulation of the Spherical Collapse Model (SCM-L) takes into account the presence of angular momentum associated with the motion of galaxy groups infalling towards the centre of galaxy clusters. The angular momentum is responsible for an additional term in the dynamical equation which is useful to describe the evolution of the clusters in the non-equilibrium region which is investigated in the present paper. Our SCM-L can be used to predict the profiles of several strategic dynamical quantities as the radial and tangential velocities of member galaxies, and the total cluster mass. A good understanding of the non-equilibrium region is important since it is the natural scenario where to study the infall in galaxy clusters and the accretion phenomena present in these objects. Our results corroborate previous estimates and are in very good agreement with the analysis of recent observations and of simulated clusters.