Much of the evolution of galaxies before they are assimilated into clusters takes place in groups where AGN feedback has the greatest impact on galaxy formation and evolution. On the other hand, clusters are the largest gravitationally bound structures in the Universe, with their baryonic mass being distributed between the constituent galaxies and the ionized plasma of their intracluster medium (ICM). As such, radio observations of galaxy clusters are powerful tools for detecting diffuse cluster-scale synchrotron emission, which carries information about the cluster formation history. In the first part of this talk, I will summarize the results from studies of the central brightest group early-type galaxies (BGEs) of an optically selected, statistically complete sample of 53 nearby groups (<80 Mpc; CLoGS sample), observed in radio 235/610 MHz (GMRT), CO (IRAM/APEX) and X-ray (Chandra and XMM-Newton) frequencies examining the jet energetics impact on the intra-group gas, the balance between hot and cold gas and the AGN activity and star formation in groups. In the second part, I will summarize the results from MeerKAT’s Galaxy Cluster Legacy Survey (MGCLS) diffuse radio emission catalogue work, a follow-up project of the first MeerKAT legacy survey paper (Knowles et al. 2022; MGCLS I) that initially was a program of long-track observations of 115 galaxy clusters at 1.28 GHz spread out over the Southern sky. I will focus on the detection rates, statistics, discoveries and properties of the various diffuse radio emission structures detected in MGCLS galaxy clusters revealing the much-improved radio images compared to previous radio observations that open up new areas of investigation in cluster formation and evolution that set the path to the SKA era.

Brief CV of Dr. Konstantinos Kolokythas:

He is a Postdoctoral Research Fellow jointly at Rhodes University and SARAO (RSA) leading the MeerKAT Galaxy Cluster Legacy Survey (MGCLS) diffuse radio emission catalogue project and the DR2 of the MGCLS products. He obtained his PhD in 2015 from the University of Birmingham (UK) studying radio properties and the evolution of nearby galaxy groups, and then he moved on as a Postdoctoral Researcher at IUCAA (Pune, India). In 2020 he joined as an NRF Postdoctoral Fellow at North-West University in South Africa. His research is focused on both galaxy groups and clusters, and in particular on the evolution of nearby galaxy groups using multi-band observations having an interest in the evolution of radio jets, their impact on the intra-group medium (AGN feedback) and the relation of active galactic nuclei and environmental properties of galaxy groups in the local Universe. In galaxy clusters, his main focus is on their evolution via the diffuse radio emission they present using MeerKAT observations.