The Importance of AGN in an Assembling Galaxy Cluster

TL;DR

This study investigates the role of AGN in a forming galaxy cluster by analyzing multi-wavelength data, revealing that a significant fraction of radio-detected members host AGN, which may influence the intrahalo medium and galaxy evolution.

Contribution

It provides new insights into the prevalence of AGN in a super galaxy group on the verge of becoming a cluster, highlighting their potential impact on the environment and galaxy properties.

Findings

30% of radio-detected members host AGN

An infrared-density relation is observed in SG1120

Radio jets detected in one of the brightest group galaxies

Abstract

We present results from our multi-wavelength study of SG1120, a super galaxy group at z=0.37, that will merge to form a galaxy cluster comparable in mass to Coma. We have spectroscopically confirmed 174 members in the four X-ray luminous groups that make up SG1120, and these groups have velocity dispersions of sigma(1D)=303-580 km/s. We find that the supergroup has an excess of 24 micron members relative to CL1358+62, a rich galaxy cluster at z=0.33. SG1120 also has an increasing fraction of 24 micron members with decreasing local galaxy density, i.e. an infrared-density relation, that is not observed in the rich cluster. We detect nine of the group galaxies in VLA 1.4 Ghz imaging, and comparison of the radio to total infrared luminosities indicates that about 30% of these radio-detected members have AGN. The radio map also reveals that one of the brightest group galaxies has radio jets. We are currently analysing the 1.4 Ghz observations to determine if AGN can significantly heat the intrahalo medium and if AGN are related to the excess of 24 micron members.