Volume 642, October 2020
|Number of page(s)||5|
|Section||Letters to the Editor|
|Published online||01 October 2020|
Letter to the Editor
ClG 0217+70: A massive merging galaxy cluster with a large radio halo and relics
Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
2 SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
3 Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, Kashiwa, Chiba 277-8583, Japan
4 Hamburger Sternwarte, University of Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
5 Dipartimento di Fisica e Astronomia, Università di Bologna, via Gobetti 93/2, 40122 Bologna, Italy
6 INAF – Istituto di Radioastronomia di Bologna, Via Gobetti 101, 40129 Bologna, Italy
7 Minnesota Institute for Astrophysics, University of Minnesota, 116 Church St. S.E., Minneapolis, MN 55455, USA
8 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
9 Department of Physics and Astronomy, University of Iowa, 203 Van Allen Hall, Iowa City, IA 52242, USA
Accepted: 14 September 2020
We present an analysis of archival Chandra data of the merging galaxy cluster ClG 0217+70. The Fe XXV Heα X-ray emission line is clearly visible in the 25 ks observation, allowing a precise determination of the redshift of the cluster as z = 0.180 ± 0.006. We measure kT500 = 8.3 ± 0.4 keV and estimate M500 = (1.06 ± 0.11) × 1015 M⊙ based on existing scaling relations. Correcting both the radio and X-ray luminosities with the revised redshift reported here, which is much larger than previously inferred based on sparse optical data, this object is no longer an X-ray underluminous outlier in the LX − Pradio scaling relation. The new redshift also means that, in terms of physical scale, ClG 0217+70 hosts one of the largest radio halos and one of the largest radio relics known to date. Most of the relic candidates lie in projection beyond r200. The X-ray morphological parameters suggest that the intracluster medium is still dynamically disturbed. Two X-ray surface brightness discontinuities are confirmed in the northern and southern parts of the cluster, with density jumps of 1.40 ± 0.16 and 3.0 ± 0.6, respectively. We also find a 700 × 200 kpc X-ray faint channel in the western part of the cluster, which may correspond to compressed heated gas or increased non-thermal pressure due to turbulence or magnetic fields.
Key words: X-rays: galaxies: clusters / galaxies: clusters: individual: ClG 0217+70 / galaxies: clusters: intracluster medium
© ESO 2020
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