A Chandra - VLA Investigation of the X-ray Cavity System and Radio Mini-Halo in the Galaxy Cluster RBS 797

TL;DR

This study combines Chandra and VLA data to analyze the X-ray cavity system and radio mini-halo in galaxy cluster RBS 797, revealing insights into AGN activity, cavity properties, and the nature of the radio emission.

Contribution

First detailed multi-wavelength analysis of RBS 797's cavity system and mini-halo, linking X-ray features with radio emission and AGN feedback mechanisms.

Findings

X-ray cavities are hotter than surrounding gas.

Bright rims are caused by gas compression from radio lobes.

Radio mini-halo follows predicted P_radio vs. P_CF trend.

Abstract

We present a study of the cavity system in the galaxy cluster RBS 797 based on Chandra and VLA data. RBS 797 (z = 0.35), is one of the most distant galaxy clusters in which two pronounced X-ray cavities have been discovered. The Chandra data confirm the presence of a cool core and indicate an higher metallicity along the cavity directions. This is likely due to the AGN outburst, which lifts cool metal-rich gas from the center along the cavities, as seen in other systems. We find indications that the cavities are hotter than the surrounding gas. Moreover, the new Chandra images show bright rims contrasting with the deep, X-ray deficient cavities. The likely cause is that the expanding 1.4 GHz radio lobes have displaced the gas, compressing it into a shell that appears as bright cool arms. Finally we show that the large-scale radio emission detected with our VLA observations may be classified as a radio mini-halo, powered by the cooling flow (CF), as it nicely follows the trend P_radio vs. P_CF predicted by the re-acceleration model.