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Article Dans Une Revue Astronomy and Astrophysics - A&A Année : 2005

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

Résumé

Application of the aperture mass (M_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_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_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_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 ≈ 0.6'') which results in a high number density of galaxies used for the weak lensing analysis (n≈ 26 arcmin-2). In five of the VLT fields, we detect a significant M_ap-signal which coincides with an overdensity of the light distribution. These detections are thus excellent candidates for shear-selected clusters.

Dates et versions

hal-03742586 , version 1 (02-08-2022)

Identifiants

Citer

Marco Hetterscheidt, Thomas Erben, P. Schneider, R. Maoli, Ludovic van Waerbeke, et al.. Searching for galaxy clusters using the aperture mass statistics in 50 VLT fields. Astronomy and Astrophysics - A&A, 2005, 442, pp.43-61. ⟨10.1051/0004-6361:20053339⟩. ⟨hal-03742586⟩
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