Evidence for AGN Feedback in Galaxy Clusters and Groups

TL;DR

Recent X-ray observations reveal that active galactic nucleus (AGN) feedback plays a crucial role in regulating the thermal state and evolution of the hot gas in galaxy clusters and groups, impacting galaxy growth and large-scale structure formation.

Contribution

This paper provides a qualitative summary of current knowledge on AGN feedback effects on the intra-cluster medium based on recent observational results.

Findings

AGN feedback influences the thermal balance of the ICM

It regulates cooling flows and star formation in galaxy clusters

Recent data supports the importance of AGN in galaxy evolution

Abstract

The current generation of flagship X-ray missions, Chandra and XMM-Newton, has changed our understanding of the so-called "cool core" galaxy clusters and groups. Instead of the initial idea that the thermal gas is cooling and flowing toward the center, the new picture envisages a complex dynamical evolution of the intra-cluster medium (ICM) regulated by the radiative cooling and the nongravitational heating from the active galactic nucleus (AGN). Understanding the physics of the hot gas and its interplay with the relativistic plasma ejected by the AGN is key for understanding the growth and evolution of galaxies and their central black holes, the history of star formation, and the formation of large-scale structures. It has thus become clear that the feedback from the central black hole must be taken into account in any model of galaxy evolution. In this paper, we draw a qualitative picture of the current knowledge of the effects of the AGN feedback on the ICM by summarizing the recent results in this field.