Radio observations of the merging galaxy cluster system Abell 3391-Abell 3395

The pre-merging system of galaxy clusters Abell 3391-Abell 3395 located at a mean redshift of 0.053 has been observed at 1 GHz in an ASKAP/EMU Early Science observation as well as in X-rays with eROSITA. The projected separation of the X-ray peaks of the two clusters is similar to 50 ' or similar to 3.1 Mpc. Here we present an inventory of interesting radio sources in this field around this cluster merger. While the eROSITA observations provide clear indications of a bridge of thermal gas between the clusters, neither ASKAP nor MWA observations show any diffuse radio emission coinciding with the X-ray bridge. We derive an upper limit on the radio emissivity in the bridge region of < J >(1 GHz) < 1.2 x 10(-44) W Hz(-1) m(-3) < J >(1GHz)<1.2x10(-44)WHz(-1)m(-3). A non-detection of diffuse radio emission in the X-ray bridge between these two clusters has implications for particle-acceleration mechanisms in cosmological large-scale structure. We also report extended or otherwise noteworthy radio sources in the 30 deg(2) field around Abell 3391-Abell 3395. We identified 20 Giant Radio Galaxies, plus 7 candidates, with linear projected sizes greater than 1 Mpc. The sky density of field radio galaxies with largest linear sizes of >0.7 Mpc is approximate to 1.7 deg(-2), three times higher than previously reported. We find no evidence for a cosmological evolution of the population of Giant Radio Galaxies. Moreover, we find seven candidates for cluster radio relics and radio halos.

Automated summary

Observations of the pre-merging system of galaxy clusters Abell 3391-Abell 3395 at a redshift of 0.053 reveal a projected separation of X-ray peaks of approximately 3.1 Mpc, with no diffuse radio emission detected in the X-ray bridge. This has implications for particle acceleration mechanisms in cosmological large-scale structure. Additionally, interesting radio sources around the cluster merger and noteworthy radio sources in the surrounding field have been identified.