An Ultra-Steep Spectrum Radio Relic in the Galaxy Cluster Abell 2443

TL;DR

This paper reports the discovery of an ultra-steep spectrum radio relic in galaxy cluster Abell 2443, likely a radio phoenix resulting from a cluster merger, characterized by its diffuse, irregular, and offset emission.

Contribution

The study presents the first deep multi-frequency observations of a new ultra-steep spectrum radio relic in Abell 2443, suggesting it belongs to the radio phoenix class.

Findings

The relic has an extremely steep, curved spectrum.

It exhibits irregular morphology and small-scale structures.

The relic is offset from the cluster center, supporting a merger origin.

Abstract

We present newly discovered radio emission in the galaxy cluster Abell 2443 which is (1) diffuse, (2) extremely steep spectrum, (3) offset from the cluster center, (4) of irregular morphology and (5) not clearly associated with any of the galaxies within the cluster. The most likely explanation is that this emission is a cluster radio relic, associated with a cluster merger. We present deep observations of Abell 2443 at multiple low frequencies (1425, 325 and 74 MHz) which help characterize the spectrum and morphology of this relic. Based on the curved spectral shape of the relic emission and the presence of small scale structure, we suggest that this new source is likely a member of the radio phoenix class of radio relics.