A deep Chandra observation of the poor cluster AWM4 - II. The role of the radio jets in enriching the intra-cluster medium

TL;DR

This study uses Chandra X-ray observations to investigate how radio jets from the central galaxy in the poor cluster AWM4 transport and enrich the intra-cluster medium with metals, particularly iron.

Contribution

It provides evidence that radio jets can uplift metal-rich gas from the galaxy core, quantifies the iron mass transported, and estimates the energy involved in this enrichment process.

Findings

Radio jets are correlated with super-solar metal abundances extending ~35 kpc.

The iron mass transported by jets is approximately 1.4 million solar masses.

The energy required for gas uplift is about 4.5x10^57 erg, a significant fraction of AGN output.

Abstract

We use a Chandra observation of the poor cluster AWM4 to map the temperature and abundance of the intra-cluster medium, so as to examine the influence of the central radio galaxy on its environment. While the cluster core is generally enriched to near-solar abundances, we find evidence of super-solar abundances correlated with the radio jets, extending ~35 kpc from the core of the central dominant galaxy NGC 6051 along its minor axis. We conclude that the enriched gas has been transported out of the central galaxy through the action of the radio source. We estimate the excess mass of iron in the entrained gas to be ~1.4x10^6 Msol, and find that this can be produced in the core of NGC 6051 within the timescale of the AGN outburst. The energy required to transport this gas to its current location is ~4.5x10^57 erg, a significant fraction of the estimated total mechanical energy output of the AGN, though this estimate is dependent on the degree of enrichment of the uplifted gas. The larger near-solar abundance region is also compatible with enrichment by metals mixed outward from NGC 6051 over a much longer timescale.