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 | |
Published online | 30 September 2005 |
Searching for galaxy clusters using the aperture mass statistics in 50 VLT fields
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
Application of the aperture mass (Map-) 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 Map-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 Map-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 Map-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 )
which results in a high number density of galaxies used for the weak lensing
analysis (
).
In five of the VLT fields, we detect a significant Map-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
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