Galaxy cluster mergers

TL;DR

This paper uses advanced hydrodynamical simulations to study galaxy cluster mergers, classifying clusters by merger history and analyzing how these events influence cluster properties and cool core formation.

Contribution

It introduces a novel halo finder applied directly to cosmological simulations and systematically examines the impact of merger events on cluster evolution and properties.

Findings

Major mergers significantly disrupt cool cores.

Merger history influences cluster scaling relations.

Simulated collisions naturally produce diverse cluster types.

Abstract

We present the results of an Eulerian adaptive mesh refinement (AMR) hydrodynamical and N-body simulation in a $\Lambda$CDM cosmology. The simulation incorporates common cooling and heating processes for primordial gas. A specific halo finder has been designed and applied in order to extract a sample of galaxy clusters directly obtained from the simulation without considering any resimulating scheme. We have studied the evolutionary history of the cluster halos, and classified them into three categories depending on the merger events they have undergone: major mergers, minor mergers, and relaxed clusters. The main properties of each one of these classes and the differences among them are discussed. The collisions among galaxy clusters are produced naturally by the non-linear evolution in the simulated cosmological volume, no controlled collisions have been considered. We pay special attention to discuss the role of merger events as a source of feedback and reheating, and their effects on the existence of cool cores in galaxy clusters, as well as in the scaling relations.