Volume 590, June 2016
|Number of page(s)||25|
|Section||Cosmology (including clusters of galaxies)|
|Published online||12 May 2016|
Weak lensing study of 16 DAFT/FADA clusters: Substructures and filaments⋆
Sorbonne Universités, UPMC Université Paris 6 et CNRS, UMR 7095, Institut
d’Astrophysique de Paris,
98bis Bd Arago,
2 Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
3 Department of Physics and Astronomy, Ohio University, 251B Clippinger Lab, Athens, OH 45701, USA
4 LAM, OAMP, Université Aix-Marseille & CNRS, Pôle de l’Étoile, Site de Château Gombert, 38 rue Frédéric Joliot-Curie, 13388 Marseille 13 Cedex, France
5 Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
6 Institut d’Astrophysique Spatiale, CNRS, UMR8617, Université Paris-Sud 11, Bâtiment 121, 91405 Orsay, France
7 Dept of Physics and Astronomy & Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA), Evanston, IL 60208-2900, USA
Received: 30 April 2015
Accepted: 15 March 2016
While our current cosmological model places galaxy clusters at the nodes of a filament network (the cosmic web), we still struggle to detect these filaments at high redshifts. We perform a weak lensing study for a sample of 16 massive, medium-high redshift (0.4 <z< 0.9) galaxy clusters from the DAFT/FADA survey, which are imaged in at least three optical bands with Subaru/Suprime-Cam or CFHT/MegaCam. We estimate the cluster masses using an NFW fit to the shear profile measured in a KSB-like method, adding our contribution to the calibration of the observable-mass relation required for cluster abundance cosmological studies. We compute convergence maps and select structures within these maps, securing their detection with noise resampling techniques. Taking advantage of the large field of view of our data, we study cluster environment, adding information from galaxy density maps at the cluster redshift and from X-ray images when available. We find that clusters show a large variety of weak lensing maps at large scales and that they may all be embedded in filamentary structures at megaparsec scale. We classify these clusters in three categories according to the smoothness of their weak lensing contours and to the amount of substructures: relaxed (~7%), past mergers (~21.5%), and recent or present mergers (~71.5%). The fraction of clusters undergoing merging events observationally supports the hierarchical scenario of cluster growth, and implies that massive clusters are strongly evolving at the studied redshifts. Finally, we report the detection of unusually elongated structures in CLJ0152, MACSJ0454, MACSJ0717, A851, BMW1226, MACSJ1621, and MS1621.
Key words: galaxies: clusters: general / gravitational lensing: weak / large-scale structure of Universe
This study is based on observations obtained with MegaCam, a joint project of CFHT and CEA/IRFU, 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. The study is also based on archive data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. This research made use of data obtained from the Chandra Data Archive provided by the Chandra X-ray Center (CXC) and data obtained from the XMM-Newton Data Archive provided by the XMM-Newton Science Archive (XSA).
© ESO, 2016
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