Detection of a pair of prominent X-ray cavities in Abell 3847

TL;DR

This paper reports the discovery of large, offset X-ray cavities in Abell 3847 caused by AGN activity, revealing insights into the cluster's cool core, shock features, and black hole accretion processes.

Contribution

It provides the first detailed analysis of offset X-ray cavities and elliptical shocks in Abell 3847, linking AGN feedback to cluster cooling and black hole accretion.

Findings

Detection of large X-ray cavities offset from radio lobes.

Presence of an elliptical shock in the cluster.

AGN power sufficient to quench cooling in the core.

Abstract

We present results obtained from a detailed analysis of a deep Chandra observation of the bright FR II radio galaxy 3C~444 in Abell~3847 cluster. A pair of huge X-ray cavities are detected along North and South directions from the centre of 3C 444. X-ray and radio images of the cluster reveal peculiar positioning of the cavities and radio bubbles. The radio lobes and X-ray cavities are apparently not spatially coincident and exhibit offsets by ~61 kpc and ~77 kpc from each other along the North and South directions, respectively. Radial temperature and density profiles reveal the presence of a cool core in the cluster. Imaging and spectral studies showed the removal of substantial amount of matter from the core of the cluster by the radio jets. A detailed analysis of the temperature and density profiles showed the presence of a rarely detected elliptical shock in the cluster. Detection of inflating cavities at an average distance of ~55 kpc from the centre implies that the central engine feeds a remarkable amount of radio power (~6.3 X 10^44 erg/s) into the intra-cluster medium over ~10^8 yr, the estimated age of cavity. The cooling luminosity of the cluster was estimated to be ~8.30 X 10^43 erg/s, which confirms that the AGN power is sufficient to quench the cooling. Ratios of mass accretion rate to Eddington and Bondi rates were estimated to be ~0.08 and 3.5 X 10^4, respectively. This indicates that the black hole in the core of the cluster accretes matter through chaotic cold accretion.