Radio and Deep Chandra Observations of the Disturbed Cool Core Cluster Abell 133

TL;DR

This study combines Chandra X-ray and multi-frequency radio observations to analyze the complex morphology, gas dynamics, and merger history of the disturbed cool core cluster Abell 133, revealing new insights into its gas structures and radio features.

Contribution

It provides new detailed observations of Abell 133, clarifies the origin of X-ray wings, and reports a previously unknown background radio galaxy affecting the cluster's radio emission.

Findings

The X-ray wings are due to gas displacement by a radio relic, not a shock.

Evidence of a recent merger event causing gas sloshing and substructure.

Discovery of a background giant radio galaxy at z=0.293.

Abstract

We present results based on new Chandra and multi-frequency radio observations of the disturbed cool core cluster Abell 133. The diffuse gas has a complex bird-like morphology, with a plume of emission extending from two symmetric wing-like features, and capped with a filamentary radio relic. X-ray observations indicate the presence of either high temperature gas or non-thermal emission in the region of the relic. We find evidence for a weak elliptical X-ray surface brightness edge surrounding the core, consistent with a sloshing cold front. The plume is consistent with having formed due to uplift by a buoyantly rising radio bubble, now seen as the radio relic. Our results are inconsistent with the previous suggestion that the X-ray wings formed due to the passage of a weak shock through the cool core. We instead conclude that the wings are due to X-ray cavities formed by gas displacement by the radio relic. The central cD galaxy contains two small-scale cold gas clumps that are slightly offset from their optical and UV counterparts, suggestive of a galaxy-galaxy merger event. On larger scales, there is evidence for cluster substructure in both optical observations and the X-ray temperature map. We suggest that Abell 133 has recently undergone a merger event with an interloping subgroup, initiating gas sloshing in the core. We show that the additional buoyant force from a passing subcluster can have a significant effect on the rise trajectories of buoyant bubbles, although this effect alone cannot fully explain the morphology of Abell 133. The radio observations reveal a previously unreported background giant radio galaxy at z = 0.293, the northern lobe of which overlies the radio relic in the core of Abell 133. A rough estimate indicates that the contribution of this background lobe to the total radio emission in the region of the relic is modest (< 13%). (Abridged)