Morphology of relaxed and merging galaxy clusters. Analytical models for monolithic Minkowski functionals

TL;DR

This paper develops analytical models using Minkowski functionals to classify and understand the diverse morphologies of galaxy clusters, including relaxed, merging, and filament-fed structures, supported by observational examples.

Contribution

It introduces novel analytical formulae and a classification scheme based on shapefinders derived from Minkowski functionals for galaxy cluster morphology.

Findings

Analytical models effectively classify different cluster morphologies.

Examples from CLASH and LC$^2$ clusters demonstrate model applicability.

New geometric formulae capture complex cluster configurations.

Abstract

Galaxy clusters exhibit a rich morphology during the early and intermediate stages of mass assembly, especially beyond their boundary. A classification scheme based on shapefinders deduced from the Minkowski functionals is examined to fully account for the morphological diversity of galaxy clusters, including relaxed and merging clusters, clusters fed by filamentary structures, and cluster-pair bridges. These configurations are conveniently treated with idealised geometric models and analytical formulae, some of which are novel. Examples from CLASH and LC$^2$ clusters and observed cluster-pair bridges are discussed.