This article has an erratum: [erratum]
Volume 532, August 2011
|Number of page(s)||26|
|Section||Cosmology (including clusters of galaxies)|
|Published online||22 July 2011|
Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
2 Isaac Newton Group of Telescopes, Calle Alvarez Abreu 70, 38700 Santa Cruz de La Palma, Spain
3 Leiden Observatory, Leiden University, Niels Bohrweg 2, 2333 Leiden, The Netherlands
4 Department of Physics and Astronomy, 6224 Agricultural Road, University of British Columbia, Vancouver, Canada
Received: 17 December 2010
Accepted: 31 March 2011
Aims. In archival 2.2 m MPG-ESO/WFI data we discovered several mass peaks through weak gravitational lensing, forming a possible supercluster at redshift 0.45. Through wide-field imaging and spectroscopy we aim to identify the supercluster centre, confirm individual member clusters, and detect possible connecting filaments.
Methods. Through multi-colour imaging with CFHT/Megaprime and INT/WFC we identify a population of early-type galaxies and use it to trace the supercluster network. EMMI/NTT multi-object spectroscopy is used to verify the initial shear-selected cluster candidates. We use weak gravitational lensing to obtain mass estimates for the supercluster centre and the filaments.
Results. We identified the centre of the SCL2243-0935 supercluster, MACS J2243-0935, which was found independently by Ebeling et al. (2001, 2010). We found 13 more clusters or overdensities embedded in a large filamentary network. Spectroscopic confirmation for about half of them is still pending. Three Mpc filaments are detected, and we estimate the global size of SCL2243 to be Mpc, making it one of the largest superclusters known at intermediate redshifts. Weak lensing yields Mpc and M200 = (1.54 ± 0.29) × 1015 M⊙ for MACS J2243 with M/L = 428 ± 82, very similar to results from size-richness cluster scaling relations. Integrating the weak lensing surface mass density over the supercluster network (defined by increased i-band luminosity or g − i colours), we find (1.53 ± 1.01) × 1015 M⊙ and M/L = 305 ± 201 for the three main filaments, consistant with theoretical predictions. The filaments’ projected dimensionless surface mass density κ varies between 0.007 − 0.012, corresponding to ρ/ρcrit = 10 − 100 depending on location and de-projection. The greatly varying density of the cosmic web is also reflected in the mean colour of galaxies, e.g. ⟨ g − i ⟩ = 2.27 mag for the supercluster centre and 1.80 mag for the filaments.
Conclusions. SCL2243 is significantly larger and much more richly structured than other known superclusters such as A901/902 or MS0302 studied with weak lensing before. It is a text-book supercluster with little contamination along the line of sight, making it a perfect sandbox for testing new techniques probing the cosmic web.
Key words: galaxies: clusters: individual: SCL2243-0935 / gravitational lensing: weak / large-scale structure of Universe / dark matter / cosmology: observations
This work is based on observations obtained with MegaPrime/MegaCam, a joint project of CFHT and CEA/DAPNIA, at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l’Univers of the Centre National de la Recherche Scientifique (CNRS) of France, and the University of Hawaii (programme ID: 2008BO01); based on observations made with ESO Telescopes at the La Silla and Paranal Observatories, Chile (ESO Programmes 165.S-0187 and 079.A-0063); based on observations made with the 2.5 m Isaac Newton Telescope operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias (programme ID 2008B/C11 and 2009B/C1).
Appendices are available in electronic form at http://www.aanda.org
© ESO, 2011
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