Testing an entropy estimator related to the dynamical state of galaxy clusters

Abstract

We propose the entropy estimator $H_Z$, calculated from global dynamical parameters, in an attempt to capture the degree of evolution of galaxy systems. We assume that the observed (spatial and velocity) distributions of member galaxies in these systems evolve over time towards states of higher dynamical relaxation (higher entropy), becoming more random and homogeneous in virial equilibrium. Thus, the $H_Z$-entropy should correspond to the gravitacional assembly state of the systems. This was tested in a sample of 70 well sampled clusters in the Local Universe whose gravitational assembly state, classified from optical and X-ray analysis of substructures, shows clear statistical correlation with $H_Z$. This estimator was also tested on a sample of clusters (halos) from the IllustrisTNG simulations, obtaining results in agreement with the observational ones.

24 pages, 9 figures and 4 tables

References in corpus (37)

• The Structure of Cold Dark Matter Halos
• Simulating the joint evolution of quasars, galaxies and their large-scale distribution
• Statistical Properties of X-ray Clusters: Analytic and Numerical Comparisons
• First results from the IllustrisTNG simulations: matter and galaxy clustering
• Tracing cosmic evolution with clusters of galaxies
• Intracluster Medium Entropy Profiles for a Chandra Archival Sample of Galaxy Clusters
• The Evolution of X-ray Clusters and the Entropy of the Intra Cluster Medium
• Galaxy Cluster Virial Masses and Omega
• Evolution of the cosmic web
• Tracing the cosmic web
• The Average Mass Profile of Galaxy Clusters
• On the efficiency and reliability of cluster mass estimates based on member galaxies
• Self-Interacting Dark Matter Halos and the Gravothermal Catastrophe
• Quantifying the Morphologies and Dynamical Evolution of Galaxy Clusters. I. The Method
• Thermodynamics of self-gravitating systems
• HIFLUGCS: Galaxy cluster scaling relations between X-ray luminosity, gas mass, cluster radius, and velocity dispersion
• Evolution of the Internal Dynamics of Galaxy Clusters
• The fraction of cool-core clusters in X-ray vs. SZ samples using Chandra observations
• X-Ray morphological analysis of the Planck ESZ clusters
• The Dynamical Equilibrium of Galaxy Clusters
• Galaxy Groups
• Gravitational instability of isothermal and polytropic spheres
• Phase-space mixing and the merging of cusps
• Conserved actions, maximum entropy and dark matter halos
• Morphology parameters: substructure identification in X-ray galaxy clusters
• On structure and kinematics of the Virgo cluster of galaxies
• Future Evolution of Bound Superclusters in an Accelerating Universe
• Galaxy evolution in Abell 85: I. Cluster substructure and environmental effects on the blue galaxy population
• Identification of filamentary structures in the environment of superclusters of galaxies in the Local Universe
• A New Method to Quantify X-ray Substructures in Clusters of Galaxies
• Physical properties of the X-ray gas as a dynamical diagnosis for galaxy clusters
• A dynamics-based density profile for dark haloes -- II. Fitting function
• Illuminating Dark Matter Halo Density Profiles Without Subhaloes
• HIFLUGCS: X-ray luminosity -- dynamical mass relation and its implications for mass calibrations with the SPIDERS and 4MOST surveys
• Large scale structure of the Universe
• The Cosmic Large-Scale Structure in X-rays (CLASSIX) cluster survey IV: Superclusters in the local Universe at z <= 0.03
• Tracing the assembly histories of galaxy clusters in the nearby universe

Cited by in corpus (1)

• Nucleation regions in the Large-Scale Structure I. A catalogue of cores in nearby rich superclusters