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  • Radio observations of the m...
    Brüggen, M.; Reiprich, T. H.; Bulbul, E.; Koribalski, B. S.; Andernach, H.; Rudnick, L.; Hoang, D. N.; Wilber, A. G.; Duchesne, S. W.; Veronica, A.; Pacaud, F.; Hopkins, A. M.; Norris, R. P.; Johnston-Hollitt, M.; Brown, M. J. I.; Bonafede, A.; Brunetti, G.; Collier, J. D.; Sanders, J. S.; Vardoulaki, E.; Venturi, T.; Kapinska, A. D.; Marvil, J.

    Astronomy and astrophysics (Berlin), 03/2021, Volume: 647
    Journal Article

    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 ~50′ or ~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 × 10 −44 W Hz −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 ≈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.