Detection of diffuse radio emission in the galaxy clusters A800, A910, A1550, and CL1446+26

TL;DR

This study used archival radio observations to discover new radio halos and relics in galaxy clusters, revealing that radio halos can be asymmetric and often offset from X-ray peaks, providing insights into cluster merger processes.

Contribution

The paper reports the discovery of new radio halos and relics in galaxy clusters using archival VLA data, highlighting their asymmetry and offsets from X-ray peaks.

Findings

New radio halos detected in A800 and A1550

Radio relic discovered in A910

Both a halo and a relic found in CL1446+26

Abstract

Radio halos are elusive sources located at the center of merging galaxy clusters. To date, only about 40 radio halos are known, thus the discovery of new halos provide important insights on this class of sources. To improve the statistics of radio halos, we investigated the radio continuum emission in a sample of galaxy clusters. We analyzed archival Very Large Array observations at 1.4 GHz, with a resolution of about 1 arcmin. These observations complemented by X-ray, optical, and higher resolution radio data allowed to detect a new radio halo in the central region of A800 and A1550. We discovered a radio relic in the periphery of A910, and finally we revealed both a halo and a relic in CL1446+26.Clusters hosting these new halos show an offset between the radio and the X-ray peak. By analyzing this offset statistically we found that radio halos can be quite asymmetric with respect to the X-ray gas distribution, with an average radio - X-ray displacement of about 180 kpc. When the offsets are normalized by the halo size, there is a tendency for smaller halos to show larger displacements.