The XXL Survey. IX. Optical overdensity and radio continuum analysis of a supercluster at z = 0.43

Baran, N.N.BaranSmolčić, V.V.SmolčićMilaković, D.D.MilakovićNovak, M.M.NovakDelhaize, J.J.DelhaizeGASTALDELLO, FABIOFABIOGASTALDELLORamos-Ceja, M. E.M. E.Ramos-CejaPacaud, F.F.PacaudBourke, S.S.BourkeCarilli, C. L.C. L.CarilliETTORI, STEFANOSTEFANOETTORIHallinan, G.G.HallinanHorellou, C.C.HorellouKoulouridis, E.E.KoulouridisCHIAPPETTI, LUCIOLUCIOCHIAPPETTIMiettinen, O.O.MiettinenMelnyk, O.O.MelnykMooley, K.K.MooleyPierre, M.M.PierrePompei, E.E.PompeiSchinnerer, E.E.Schinnerer2020-05-152020-05-1520160004-6361http://hdl.handle.net/20.500.12386/24883We 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="http://cosmosdb.iasf-milano.inaf.it/XXL">http://cosmosdb.iasf-milano.inaf.it/XXL</A>. A copy of the catalogue and the mosaic are also available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?IX/49">http://cdsarc.u-strasbg.fr/viz-bin/qcat?IX/49</A>A FITS file of the reduced image is only available at the CDS via anonymous ftp to <A href="http://cdsarc.u-strasbg.fr">http://cdsarc.u-strasbg.fr</A> (<A href="http://130.79.128.5">http://130.79.128.5</A>) or via <A href="http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A8">http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/592/A8</A>ELETTRONICOenThe XXL Survey. IX. Optical overdensity and radio continuum analysis of a supercluster at z = 0.43Article10.1051/0004-6361/2015269522-s2.0-84975497546000384722600022https://www.aanda.org/articles/aa/abs/2016/08/aa26952-15/aa26952-15.html2016A&A...592A...8BFIS/05 - ASTRONOMIA E ASTROFISICAERC sectors::Physical Sciences and Engineering::PE9 Universe sciences: astro-physics/chemistry/biology; solar systems; stellar, galactic and extragalactic astronomy, planetary systems, cosmology, space science, instrumentation