Thermo-dynamic and chemical properties of the Intra-Cluster Medium

TL;DR

This study investigates the thermodynamic and chemical properties of galaxy clusters to understand their evolutionary history, focusing on the cool core/non-cool core division and the impact of mergers and heating events.

Contribution

It classifies clusters based on thermo-dynamic and chemical properties, revealing links between entropy, metallicity, and dynamical state, and suggests evolutionary pathways involving heating events.

Findings

Most merging systems have high entropy cores.

Clusters with lower entropy cores have more pronounced metallicity peaks.

Outliers with high metallicity and high entropy are often mergers.

Abstract

Aims. We aim to provide constraints on evolutionary scenarios in clusters. One of our main goals is to understand whether, as claimed by some, the cool core/non-cool core division is established once and for all during the early history of a cluster. Methods. We employ a sample of about 60 objects to classify clusters according to different properties: we characterize cluster cores in terms of their thermo-dynamic and chemical properties and clusters as a whole in terms of their dynamical properties. Results. We find that: I) the vast majority of merging systems feature high entropy cores (HEC); II) objects with lower entropy cores feature more pronounced metallicity peaks than objects with higher entropy cores. We identify a small number of medium (MEC) and high (HEC) entropy core systems which, unlike most other such objects, feature a large central metallicity. The majority of these outliers are mergers, i.e. systems far from their equilibrium configuration. Conclusions. We surmise that medium (MEC) and high (HEC) entropy core systems with a large central metallicity recently evolved from low entropy core (LEC) clusters that have experienced a heating event associated to AGN or merger activity.