Cool-Core Destruction in Merging Clusters with AGN Feedback and Radiative Cooling

TL;DR

This study uses 3D simulations to explore how galaxy cluster mergers, combined with AGN feedback and radiative cooling, influence the destruction or preservation of cool-core clusters, revealing that merger parameters and AGN activity jointly determine CC fate.

Contribution

The paper introduces detailed 3D merger simulations including AGN feedback and cooling to clarify their combined role in cool-core destruction and transition mechanisms.

Findings

AGN feedback is crucial for regulating cooling in mergers.

CC destruction depends on merger mass ratio and impact parameter.

Multiple scenarios for CC/NCC transition are identified.

Abstract

The origin of cool-core (CC) and non-cool-core (NCC) dichotomy of galaxy clusters remains uncertain. Previous simulations have found that cluster mergers are effective in destroying CCs but fail to prevent overcooling in cluster cores when radiative cooling is included. Feedback from active galactic nuclei (AGN) is a promising mechanism for balancing cooling in CCs; however, the role of AGN feedback in CC/NCC transitions remains elusive. In this work, we perform three-dimensional binary cluster merger simulations incorporating AGN feedback and radiative cooling, aiming to investigate the heating effects from mergers and AGN feedback on CC destruction. We vary the mass ratio and impact parameter to examine the entropy evolution of different merger scenarios. We find that AGN feedback is essential in regulating the merging clusters, and that CC destruction depends on the merger parameters. Our results suggest three scenarios regarding CC/NCC transitions: (1) CCs are preserved in minor mergers or mergers that do not trigger sufficient heating, in which cases AGN feedback is crucial for preventing the cooling catastrophe; (2) CCs are transformed into NCCs by major mergers during the first core passage, and AGN feedback is subdominant; (3) in major mergers with a large impact parameter, mergers and AGN feedback operate in concert to destroy the CCs.