AGN feedback and iron enrichment in the powerful radio galaxy, 4C+55.16

TL;DR

This study analyzes the X-ray and radio observations of the galaxy 4C+55.16, revealing AGN-driven outbursts, complex iron enrichment patterns, and a possible cold front, highlighting the galaxy's energetic interactions with its cluster environment.

Contribution

It provides the first detailed X-ray analysis of 4C+55.16, uncovering multiple AGN outbursts, unusual iron distribution, and evidence of gas uplift and cold front phenomena.

Findings

AGN outbursts can offset ICM cooling.

Iron-rich plume correlates with X-ray cavities.

Temperature and metallicity discontinuity suggests a cold front.

Abstract

We present a detailed X-ray analysis of 4C+55.16, an unusual and interesting radio galaxy, located at the centre of a cool core cluster of galaxies. 4C+55.16 is X-ray bright (L(cluster)~10^45 erg/s), radio powerful, and shows clear signs of interaction with the surrounding intracluster medium. By combining deep Chandra (100 ks) with 1.4 GHz VLA observations, we find evidence of multiple outbursts from the central AGN, providing enough energy to offset cooling of the ICM (P_bubbles=6.7x10^44 erg/s). Furthermore, 4C+55.16 has an unusual intracluster iron distribution showing a plume-like feature rich in Fe L emission that runs along one of the X-ray cavities. The excess of iron associated with the plume is around 10^7M_sol. The metal abundances are consistent with being Solar-like, indicating that both SNIa and SNII contribute to the enrichment. The plume and southern cavity form a region of cool metal-rich gas, and at the edge of this region, there is a clear discontinuity in temperature (from kT~2.5 keV to kT~5.0 keV), metallicity (from ~0.4 solar to 0.8 solar), and surface brightness distribution, consistent with it being caused by a cold front. However, we also suggest that this discontinuity could be caused by cool metal-rich gas being uplifted from the central AGN along one of its X-ray cavities.