Galaxy clusters in the CFHTLS

First matched filter candidate catalogue of the Deep fields

¹ Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen, Denmark e-mail: lisbeth@dark-cosmology.dk
² Observatoire de la Côte d'Azur, Laboratoire Cassiopée, BP 4229, 06304 Nice Cedex 4, France
³ INAF - Osservatorio Astronomico di Bologna, Via Ranzani 1, 40127 Bologna, Italy
⁴ Laboratoire d'Astrophysique de Marseille, UMR 6110 CNRS-Université de Provence, BP 8, 13376 Marseille Cedex 12, France
⁵ Institut für Astro- und Teilchen Physik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria

Received: 21 July 2006
Accepted: 19 September 2006

Abstract

We apply a matched-filter cluster detection algorithm to the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) i-band data for the Deep-1, Deep-2, Deep-3 and Deep-4 fields covering a total of 4 square degrees. To test the implemented procedure we carry out simulations for assessing the frequency of noise peaks as well as estimate the recovery efficiency. We estimate that up to the catalogue is essentially complete for clusters of richness class . The recovered redshifts are in general overestimated by with a scatter of , except at redshifts where the estimated redshifts are systematically underestimated. The constructed cluster candidate catalogue contains 162 detections over an effective area of 3.112 square degrees corresponding to a density of ~52.1 per square degree. The median estimated redshift of the candidates is . The estimated noise frequency is detections per square degree. From visual inspection we identify systems that show a clear concentration of galaxies with similar colour. These systems have a density of ~20 per square degree.