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Issue A&A
Volume 442, Number 3, November II 2005
Page(s) 851 - 860
Section Cosmology (including clusters of galaxies)
DOI http://dx.doi.org/10.1051/0004-6361:20042600



A&A 442, 851-860 (2005)
DOI: 10.1051/0004-6361:20042600

An optimal filter for the detection of galaxy clusters through weak lensing

M. Maturi1, 2, 3, 4, M. Meneghetti1, M. Bartelmann1, K. Dolag2, 3 and L. Moscardini4

1  Zentrum für Astronomie, ITA, Universität Heidelberg, Albert-Überle-Str. 2, 69120 Heidelberg, Germany
2  Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio 2, 35120 Padova, Italy
3  Max-Planck-Institut für Astrophysik, PO Box 1523, 85740 Garching, Germany
4  Dipartimento di Astronomia, Università di Bologna, Via Ranzani 1, 40127 Bologna, Italy

(Received 23 December 2004 / Accepted 27 July 2005 )

Abstract
We construct a linear filter optimised for detecting dark-matter halos in weak-lensing data. The filter assumes a mean radial profile of the halo shear pattern and modifies that shape by the noise power spectrum. Aiming at separating dark-matter halos from spurious peaks caused by large-scale structure lensing, we model the noise as being composed of weak lensing by large-scale structures and Poisson noise from random galaxy positions and intrinsic ellipticities. Optimal filtering against the noise requires the optimal filter scale to be smaller than typical halo sizes. Although a perfect separation of halos from spurious large-scale structure peaks is strictly impossible, we use numerical simulations to demonstrate that our filter produces substantially more sensitive, reliable and stable results than the conventionally used aperture-mass statistic.


Key words: cosmology: theory -- galaxies: clusters: general -- gravitational lensing




© ESO 2005


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