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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 731958.0, MPI für Astronomie / Publikationen_mpia
The XXL Survey. IX. Optical overdensity and radio continuum analysis of a supercluster at z = 0.43
Authors:Baran, N.; Smolčić, V.; Milaković, D.; Novak, M.; Delhaize, J.; Gastaldello, F.; Ramos-Ceja, M. E.; Pacaud, F.; Bourke, S.; Carilli, C. L.; Ettori, S.; Hallinan, G.; Horellou, C.; Koulouridis, E.; Chiappetti, L.; Miettinen, O.; Melnyk, O.; Mooley, K.; Pierre, M.; Pompei, E.; Schinnerer, E.
Date of Publication (YYYY-MM-DD):2016
Title of Journal:Astronomy and Astrophysics
Start Page:id. A8 (15 pp)
Audience:Not Specified
Abstract / Description:We present observations with the Karl G. Jansky Very Large Array (VLA) at 3 GHz (10 cm) toward a sub-field of the XXL-North 25 deg2 field targeting the first supercluster discovered in the XXL Survey. The structure has been found at a spectroscopic redshift of 0.43 and extending over 0.̊35 × 0.̊1 on the sky. The aim of this paper is twofold. First, we present the 3 GHz VLA radio continuum observations, the final radio mosaic and radio source catalogue, and, second, we perform a detailed analysis of the supercluster in the optical and radio regimes using photometric redshifts from the CFHTLS survey and our new VLA-XXL data. Our final 3 GHz radio mosaic has a resolution of 3.̋2 × 1.̋9, and encompasses an area of 41' × 41' with rms noise level lower than ~ 20 μJy beam-1. The noise in the central 15' × 15' region is ≈ 11 μJy beam-1. From the mosaic we extract a catalogue of 155 radio sources with signal-to-noise ratio (S/N) ≥ 6, eight of which are large, multicomponent sources, and 123 (79%) of which can be associated with optical sources in the CFHTLS W1 catalogue. Applying Voronoi tessellation analysis (VTA) in the area around the X-ray identified supercluster using photometric redshifts from the CFHTLS survey we identify a total of seventeen overdensities at zphot = 0.35 - 0.50, 7 of which are associated with clusters detected in the XMM-Newton XXL data. We find a mean photometric redshift of 0.43 for our overdensities, consistent with the spectroscopic redshifts of the brightest cluster galaxies of seven X-ray detected clusters. The full VTA-identified structure extends over ~ 0.̊6 × 0.̊2 on the sky, which corresponds to a physical size of ~ 12 × 4 Mpc2 at z = 0.43. No large radio galaxies are present within the overdensities, and we associate eight (S/N> 7) radio sources with potential group/cluster member galaxies. The spatial distribution of the red and blue VTA-identified potential group member galaxies, selected by their observed g - r colours, suggests that the clusters are not virialised yet, but are dynamically young, as expected for hierarchical structure growth in a ΛCDM universe. Further spectroscopic data are required to analyse the dynamical state of the groups. The full catalogue is available as a queryable database table XXL_VLA_15 via the XXL Master Catalogue browser <A href=""></A>. A copy of the catalogue and the mosaic are also available at the CDS via anonymous ftp to <A href=""></A> (<A href=""></A>) or via <A href=""></A>A FITS file of the reduced image is only available at the CDS via anonymous ftp to <A href=""></A> (<A href=""></A>) or via <A href=""></A>
Free Keywords:catalogs; galaxies: clusters: general; galaxies: groups: general; radio continuum: galaxies
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-6361 %R 10.1051/0004-6361/201526952
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