Observations of a nearby filament of galaxy clusters with the Sardinia Radio Telescope

TL;DR

This study reports the detection of diffuse radio emission potentially linked to a cosmic web filament near galaxy clusters, revealing new large-scale synchrotron sources and a candidate giant radio galaxy, advancing understanding of cosmic magnetism.

Contribution

It presents the first combined radio observations of a large-scale filament with new candidate diffuse sources, highlighting the cosmic web's magnetic properties.

Findings

Detection of diffuse radio emission possibly associated with a cosmic web filament.

Identification of 28 candidate large-scale diffuse sources with unique properties.

Discovery of a candidate new giant radio galaxy.

Abstract

We report the detection of diffuse radio emission which might be connected to a large-scale filament of the cosmic web covering a 8deg x 8deg area in the sky, likely associated with a z~0.1 over-density traced by nine massive galaxy clusters. In this work, we present radio observations of this region taken with the Sardinia Radio Telescope. Two of the clusters in the field host a powerful radio halo sustained by violent ongoing mergers and provide direct proof of intra-cluster magnetic fields. In order to investigate the presence of large-scale diffuse radio synchrotron emission in and beyond the galaxy clusters in this complex system, we combined the data taken at 1.4 GHz obtained with the Sardinia Radio Telescope with higher resolution data taken with the NRAO VLA Sky Survey. We found 28 candidate new sources with a size larger and X-ray emission fainter than known diffuse large-scale synchrotron cluster sources for a given radio power. This new population is potentially the tip of the iceberg of a class of diffuse large-scale synchrotron sources associated with the filaments of the cosmic web. In addition, we found in the field a candidate new giant radio galaxy.