Volume 442, Number 3, November II 2005
|Page(s)||851 - 860|
|Section||Cosmology (including clusters of galaxies)|
|Published online||14 October 2005|
An optimal filter for the detection of galaxy clusters through weak lensing
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
Accepted: 27 July 2005
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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