A low-frequency radio halo survey of the South Pole Telescope SZ-selected clusters with the GMRT

TL;DR

This study conducted a low-frequency radio survey of high-redshift galaxy clusters using GMRT, discovering new radio halos and setting upper limits, thereby expanding understanding of non-thermal phenomena in the intra-cluster medium.

Contribution

First low-frequency survey of z>0.3 clusters with GMRT, discovering new radio halos and providing upper limits to improve knowledge of non-thermal emissions in distant clusters.

Findings

Discovered 2 new radio halos in high-redshift clusters.

Detected a halo candidate and confirmed previous detections.

Upper limits suggest potential for future detections with more sensitive observations.

Abstract

The presence of non-thermal electrons and large scale magnetic fields in the intra-cluster medium (ICM) is known through the detection of mega-parsec (Mpc) scale diffuse radio synchrotron emission. Although a significant amount of progress in finding new diffuse radio sources has happened in the last decade, most of the investigation has been constrained towards massive low-redshift clusters. In this work, we explore clusters with redshift $z>0.3$ in search of diffuse radio emission, at 325 MHz with the Giant Metrewave Radio Telescope (GMRT). This campaign has resulted in the discovery of 2 new radio halos (SPT-CL J0013-4906 and SPT-CL J0304-4401) along with 2 other detections (SPT-CL J2031-4037 and SPT-CL J2248-4431), previously reported (at 325 MHz) in the literature. In addition, we detect a halo candidate in 1 cluster in our sample, and upper limits for halos are placed in 8 clusters where no diffuse emission is detected. In the $P_{1.4} - L_\mathrm{X}$ plane, the detected halos follow the observed correlation, whereas the upper limits lie above the correlation line, indicating the possibility of future detection with sensitive observations.