Radio properties of nearby groups of galaxies

TL;DR

This study investigates the radio properties of nearby galaxy groups using multi-frequency radio and X-ray observations to understand AGN activity and its impact on intra-group gas and galaxy evolution.

Contribution

It provides new insights into the age, activity, and remnants of AGN in galaxy groups through low-frequency radio observations and multi-wavelength analysis.

Findings

Radio source 3C270 in NGC 4261 is approximately 18 Myr old.

Detected a small-scale jet in NGC 1060 indicating an old outburst.

In NGC 5982, the central AGN shows no jets or lobes, with diffuse emission from star-forming disks.

Abstract

Much of the evolution of galaxies takes place in groups where feedback has the greatest impact on galaxy formation. By using an optically selected, statistically complete sample of 53 nearby groups (CLoGS), observed in Radio (GMRT) and in X-rays (Chandra and XMM-Newton), we aim to characterize the radio-AGN population in groups and examine their impact on the intra-group gas and member galaxies. The sensitivity to older electron populations at 240 MHz and the resolution of 610 MHz is the key to identify past and current AGN activity. Here we will present first results from three different galaxy groups analysed so far. We report an age of ~18 Myr for the radio source 3C270 in NGC 4261 implying that the expansion was supersonic over a large fraction of its lifetime. In NGC 1060 we detect a small-scale (20''/7.4 kpc) jet source with the spectral index of $\alpha_{240}^{610}$=0.9 indicating a remnant of an old outburst. Lastly in NGC 5982 the 610 and 235 MHz observations find a radio point source in the central AGN with no evidence of jets or lobes and diffuse emission from the disks (star formation).