The XXL Survey. XXXIV. Double Irony in XXL-North: a tale of two radio galaxies in a supercluster at z = 0.14

Horellou, C. and Intema, H. T. and Smolčić, Vernesa and Nilsson, A. and Karlsson, A. and Krook, C. and Tolliner, L. and Adami, C. and Benoist, C. and Birkinshaw, M. and Caretta, C. and Chiappetti, L. and Delhaize, J. and Ferrari, C. and Fotopoulou, S. and Guglielmo, V. and Kolokythas, Konstantinos and Pacaud, F. and Pierre, M. and Poggianti, B. M. and Ramos-Ceja, M. E. and Raychaudhury, S. and Röttgering, H. J. A. and Vignali, C. (2018) The XXL Survey. XXXIV. Double Irony in XXL-North: a tale of two radio galaxies in a supercluster at z = 0.14. Astronomy and Astrophysics, 620. A19-1-A19-23. ISSN 0004-6361

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Aims. We show how the XXL multiwavelength survey can be used to shed light on radio galaxies and their environment. Methods. Two prominent radio galaxies were identified in a visual examination of the mosaic of XXL-North obtained with the Giant Metrewave Radio Telescope at 610 MHz. Counterparts were searched for in other bands. Spectroscopic redshifts from the GAMA database were used to identify clusters and/or groups of galaxies, estimate their masses with the caustic method, and quantify anisotropies in the surrounding galaxy distribution via a Fourier analysis. Results. Both radio galaxies are of FR I type and are hosted by early-type galaxies at a redshift of 0.138. The first radio source, named the Exemplar, has a physical extent of ~400 kpc; it is located in the cluster XLSSC 112, which has a temperature of ~2 keV, a total mass of ~10^14 M_⊙, and resides in an XXL supercluster with eight known members. The second source, named the Double Irony, is a giant radio galaxy with a total length of about 1.1 Mpc. Its core coincides with a cataloged point-like X-ray source, but no extended X-ray emission from a surrounding galaxy cluster was detected. However, from the optical data we determined that the host is the brightest galaxy in a group that is younger, less virialized, and less massive than the Exemplar’s cluster. A friends-of-friends analysis showed that the Double Irony’s group is a member of the same supercluster as the Exemplar. There are indications that the jets and plumes of the Double Irony have been deflected by gas associated with the surrounding galaxy distribution. Another overdensity of galaxies (the tenth) containing a radio galaxy was found to be associated with the supercluster. Conclusions. Radio Galaxies can be used to find galaxy clusters/groups that are below the current sensitivity of X-ray surveys.

Item Type: Article
Keywords: radiation mechanisms: non-thermal; radio continuum: galaxies; galaxies: active; galaxies: magnetic fields; methods: data analysis
Date: 20 November 2018
Subjects: NATURAL SCIENCES > Physics > Astronomy and Astrophysics
Additional Information: © ESO 2018. Received 6 March 2018; Accepted 12 July 2018; Published online 20 November 2018.
Divisions: Faculty of Science > Department of Physics
Publisher: EDP Sciences
Depositing User: Vernesa Smolčić
Date Deposited: 02 May 2019 12:51
Last Modified: 06 May 2019 12:42

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