EDP Sciences
Free Access
Issue
A&A
Volume 442, Number 1, October IV 2005
Page(s) 43 - 61
Section Cosmology (including clusters of galaxies)
DOI https://doi.org/10.1051/0004-6361:20053339


A&A 442, 43-61 (2005)
DOI: 10.1051/0004-6361:20053339

Searching for galaxy clusters using the aperture mass statistics in 50 VLT fields

M. Hetterscheidt1, T. Erben1, P. Schneider1, R. Maoli2, 3, L. Van Waerbeke4 and Y. Mellier3, 5

1  Institut für Astrophysik und Extraterrestrische Forschung (IAEF), Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
    e-mail: mhetter@astro.uni-bonn.de
2  Department of Physics, University "La Sapienza", P.le A. Moro 2, 00185, Rome, Italy
3  Institut d'Astrophysique de Paris, UMR 7095 CNRS, Université Pierre & Marie Curie, 98bis boulevard Arago, 75014 Paris, France
4  Department of Physics and Astronomy, University of British Columbia, Agricultural Road 6224, Vancouver, V6T 1Z1, B.C., Canada
5  Observatoire de Paris, LERMA, 61 avenue de l'Observatoire, 75014 Paris, France

(Received 29 April 2005 / Accepted 30 June 2005)

Abstract
Application of the aperture mass ( $M_{\rm ap}$-) statistics provides a weak lensing method for the detection of cluster-sized dark matter halos. We present a new aperture filter function and maximise the effectiveness of the $M_{\rm ap}$-statistics to detect cluster-sized halos using analytical models. We then use weak lensing mock catalogues generated from ray-tracing through N-body simulations, to analyse the effect of image treatment on the expected number density of halos. Using the $M_{\rm ap}$-statistics, the aperture radius is typically several arcminutes, hence the aperture often lies partly outside a data field, consequently the signal-to-noise ratio of a halo detection decreases. We study these border effects analytically and by using mock catalogues. We find that the expected number density of halos decreases by a factor of two if the size of a field is comparable to the diameter of the aperture used. We finally report on the results of a weak lensing cluster search applying the $M_{\rm ap}$-statistics to 50 randomly selected fields which were observed with FORS1 at the VLT. Altogether the 50 VLT fields cover an area of 0.64 square degrees. The I-band images were taken under excellent seeing conditions (average seeing $\approx 0\hbox{$.\!\!^{\prime\prime}$ }6$) which results in a high number density of galaxies used for the weak lensing analysis ( $n\approx 26\,{\rm arcmin}^{-2}$). In five of the VLT fields, we detect a significant $M_{\rm ap}$-signal which coincides with an overdensity of the light distribution. These detections are thus excellent candidates for shear-selected clusters.


Key words: gravitational lensing -- galaxies clusters: general




© ESO 2005

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.