The content discusses testing an entropy estimator related to the dynamical state of galaxy clusters. The proposed entropy estimator, HZ, is calculated from global dynamical parameters to capture the degree of evolution of galaxy systems. The study aims to correlate this entropy with the gravitational assembly state of clusters. Key points include hierarchical formation models, stability in equilibrium states, and estimating evolutionary states using observational data.
Galaxies cluster due to gravitational forces forming complex structures in the universe known as Large-Scale Structure (LSS). Systems range from small groups to superclusters embedded in LSS. Knot-shaped regions called galaxy groups or clusters are categorized by richness based on the number of galaxies they contain.
Clusters are classified based on their expected virialized zones rather than ad hoc criteria like richness. Baryonic matter accounts for only 15% of a cluster's mass with dark matter contributing significantly more.
Galaxies serve as tracers for observing global dynamics within a system. The process of cluster formation and evolution involves various physical mechanisms driven by gravity leading to dynamical relaxation and eventual virialization.
The content introduces an entropy estimator, HZ, that combines optical observational parameters like virial mass and velocity dispersion to quantify the evolutionary state of galaxy systems. It suggests that galaxies evolve towards higher entropy states during dynamical relaxation.
Testing the HZ-entropy estimator involves comparing it with assembling states classification applied to observational samples and calculating Shannon entropy for different regions within each cluster's phase-space.
Observational data from well-sampled galaxy clusters is used to test the proposed entropy estimator and establish correlations between HZ values and observed evolutionary states based on substructures present in clusters.
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