Accretion powered AGN feedback in the cores of galaxy clusters

TL;DR

This paper discusses how active galactic nuclei (AGN) feedback mechanisms, particularly accretion-powered processes, regulate the cooling of hot plasma in galaxy cluster cores, addressing the cooling flow paradox.

Contribution

It provides an overview of AGN feedback processes in galaxy clusters, emphasizing their role in balancing radiative cooling and their observable signatures.

Findings

AGN feedback counteracts cooling flows in galaxy clusters

Observational signatures of AGN activity in cluster cores

Addresses the cooling flow paradox in galaxy clusters

Abstract

Detection of the copious amount of X-ray emission from the dilute hot plasma in galaxy clusters suggests that a substantial fraction of the central intracluster medium (ICM) is cooling radiatively on a time scale much faster than the Hubble time. Theoretical models predict the cooling rate as high as about few hundred to few thousand solar mass per year, which would be then made available for the formation of new stars in the core of these clusters. However, systematic studies of the cores of such clusters failed to detect the expected reservoirs of cooled gas. Thus, the gas in the cores of galaxy clusters is losing substantial amount of energy in the form of X-rays but is not cooling. This in turn point towards the famous cooling flow paradox and hence demands some intermittent heating to balance the cooling over such a long period. Several sources have been suggested to counteract on the cooling of the ICM, however, the AGN feedback appeared to be the most promising and enough energetic source to resist cooling of the ICM in the cores of such clusters. In this presentation I will provide a brief overview on the feedback processes that are involved in the cores of the galaxy clusters with an emphasis on the AGN feedback and its observable signatures.