Weak lensing mass reconstructions of the ESO Distant Cluster Survey

¹ Institut für Astrophysik und Extraterrestrische Forschung der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany e-mail: dclowe@as.arizona.edu
² Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721, USA
³ School of Physics and Astronomy, University of Nottingham, NG7 2RD, UK
⁴ Department of Physics, Bristol University, H H Wills Physics Laboratory, Tyndall Avenue, Bristol, BS8 1TL, UK
⁵ Max–Planck–Institut für Astrophysik, Karl–Schwarschild–Str. 1, Postfach 1317, 85741 Garching, Germany
⁶ Osservatorio Astronomico, vicolo dell'Osservatorio 5, 35122 Padova, Italy
⁷ Institut für Astrophysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
⁸ GEPI, CNRS-RMS8111, Observatoire de Paris, section de Meudon, 5 Place Jules Janssen, 92195 Meudon Cedex, France
⁹ Max–Planck–Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
¹⁰ Laboratoire de'Astrophysique, UMR 5572, Observatoire Midi-Pyrénées, 14 Avenue E. Belin, 31400 Toulouse, France
¹¹ Herzberg Institute of Astrophysics, National Research Council of Canada, Victoria, BC V93 2E7, Canada

Received: 4 August 2004
Accepted: 24 November 2005

Abstract

We present weak lensing mass reconstructions for the 20 high-redshift clusters in the ESO Distant Cluster Survey. The weak lensing analysis was performed on deep, 3-color optical images taken with VLT/FORS2, using a composite galaxy catalog with separate shape estimators measured in each passband. We find that the EDisCS sample is composed primarily of clusters that are less massive than those in current X-ray selected samples at similar redshifts, but that all of the fields are likely to contain massive clusters rather than superpositions of low mass groups. We find that 7 of the 20 fields have additional massive structures which are not associated with the clusters and which can affect the weak lensing mass determination. We compare the mass measurements of the remaining 13 clusters with luminosity measurements from cluster galaxies selected using photometric redshifts and find evidence of a dependence of the cluster mass-to-light ratio with redshift. Finally we determine the noise level in the shear measurements for the fields as a function of exposure time and seeing and demonstrate that future ground-based surveys which plan to perform deep optical imaging for use in weak lensing measurements must achieve point-spread functions smaller than a median of FWHM.