Volume 647, March 2021
First science highlights from SRG/eROSITA
|Number of page(s)||16|
|Published online||26 February 2021|
Radio observations of the merging galaxy cluster system Abell 3391-Abell 3395★
University of Hamburg,
2 Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, Germany
3 Max-Planck-Institut für extraterrestrische Physik, Giessenbachstraße 1, 85748 Garching, Germany
4 CSIRO Astronomy & Space Science, PO Box 76, Epping, NSW 1710, Australia
5 Departmento de Astronomía, Universidad de Guanajuato, Callejón de Jalisco s/n, Guanajuato, C.P. 36023, GTO, Mexico
6 Minnesota Institute for Astrophysics, University of Minnesota, 116 Church St. SE, Minneapolis, MN 55455, USA
7 International Centre for Radio Astronomy Research (ICRAR), Curtin University, Bentley, WA 6102, Australia
8 Australian Astronomical Optics, Macquarie University, 105 Delhi Rd, North Ryde, NSW 2113, Australia
9 Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
10 School of Physics & Astronomy, Monash University, Clayton, VIC 3800, Australia
11 The Inter-University Institute for Data Intensive Astronomy (IDIA), Department of Astronomy, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
12 School of Science, Western Sydney University, Locked Bag 1797, Penrith, NSW 2751, Australia
13 DIFA – Universitá di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
14 INAF, Istituto di Radioastronomia, Via Gobetti 101, 40129 Bologna, Italy
15 Curtin Institute for Computation, Curtin University, GPO Box U 1987, Perth, WA 6845, Australia
16 Thüringer Landessternwarte, Sternwarte 5, 07778 Tautenburg, Germany
17 NRAO, PO Box 0, Socorro 87801, NM, USA
Accepted: 11 November 2020
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 deg2 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.
Key words: X-rays: galaxies: clusters / radio continuum: galaxies / galaxies: clusters: intracluster medium
The ASKAP mosaic is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (188.8.131.52) or via http://cdsarc.u-strasbg.fr/viz-bin/cat/J/A+A/647/A3
© ESO 2021
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