Tracing low-mass galaxy clusters with radio relics: the discovery of Abell 3527-bis

TL;DR

This study demonstrates that radio relics can be used to identify low-mass galaxy clusters, exemplified by the discovery of Abell 3527-bis, a previously unknown cluster with a radio relic, using multi-wavelength data.

Contribution

The paper shows that radio relics are effective tracers for low-mass galaxy clusters, expanding detection methods beyond traditional X-ray and SZ surveys.

Findings

Confirmed the presence of a 1 Mpc radio relic in Abell 3527-bis.

Established the galaxy cluster's existence through optical and X-ray data.

Identified Abell 3527-bis as one of the least massive clusters with a radio relic.

Abstract

Galaxy clusters undergo mergers that can generate extended radio sources called radio relics. Radio relics are the consequence of merger-induced shocks that propagate in the intra cluster medium (ICM). In this paper we analyse the radio, optical and X-ray data from a candidate galaxy cluster that has been selected from the radio emission coming from a candidate radio relic detected in NRAO VLA Sky Survey (NVSS). Our aim is to clarify the nature of this source and prove that under certain conditions radio emission from radio relics can be used to trace relatively low-mass galaxy clusters. We have observed the candidate galaxy cluster with the Giant Meterwave Radio Telescope (GMRT) at three different frequencies. These datasets have been analysed together with archival data from ROSAT in the X-ray and with archival data from the Gamma-Ray Burst Optical/Near-Infrared Detector (GROND) telescope in four different optical bands. We confirm the presence of a 1 Mpc long radio relic located in the outskirts of a previously unknown galaxy cluster. We confirm the presence of the galaxy cluster through dedicated optical observations and using archival X-ray data. Due to its proximity and similar redshift to a known Abell cluster, we named it: Abell 3527-bis. The galaxy cluster is among the least massive cluster known to host a radio relic. We showed that radio relics can be effectively used to trace a subset of relatively low-mass galaxy clusters that might have gone undetected in X-ray or Sunyaev-Zel'dovich (SZ) surveys. This technique might be used in future deep, low-frequency surveys as those carried on by LOFAR, uGMRT and, ultimately, SKA.