The relation between the diffuse X-ray luminosity and the radio power of the central AGN in galaxy groups

TL;DR

This study investigates the relationship between X-ray luminosity and radio power of central AGNs in galaxy groups, revealing similar correlations to clusters and suggesting effective feedback processes in groups.

Contribution

It provides the first comprehensive analysis of the X-ray and radio emission relation in galaxy groups using deep VLA and MeerKAT data, comparing with galaxy clusters.

Findings

Clusters and groups follow the same X-ray-radio correlation.

Large radio galaxies increase scatter in the relation.

Galaxy groups are more likely to host large radio galaxies.

Abstract

Our understanding of how AGN feedback operates in galaxy clusters has improved in recent years owing to large efforts in multi-wavelength observations and hydrodynamical simulations. However, it is much less clear how feedback operates in galaxy groups, which have shallower gravitational potentials. In this work, using very deep VLA and new MeerKAT observations from the MIGHTEE survey, we compiled a sample of 247 X-ray selected galaxy groups detected in the COSMOS field. We have studied the relation between the X-ray emission of the intra-group medium and the 1.4 GHz radio emission of the central radio galaxy. For comparison, we have also built a control sample of 142 galaxy clusters using ROSAT and NVSS data. We find that clusters and groups follow the same correlation between X-ray and radio emission. Large radio galaxies hosted in the centres of groups and merging clusters increase the scatter of the distribution. Using statistical tests and Monte-Carlo simulations, we show that the correlation is not dominated by biases or selection effects. We also find that galaxy groups are more likely than clusters to host large radio galaxies, perhaps owing to the lower ambient gas density or a more efficient accretion mode. In these groups, radiative cooling of the ICM could be less suppressed by AGN heating. We conclude that the feedback processes that operate in galaxy clusters are also effective in groups.