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Issue A&A Volume 429, Number 2, January II 2005 Page(s) 417 - 426 Section Cosmology (including clusters of galaxies) DOI 10.1051/0004-6361:20048093

A&A 429, 417-426 (2005)
DOI: 10.1051/0004-6361:20048093

The selection function of SZ cluster surveys

J.-B. Melin, J. G. Bartlett and J. Delabrouille

APC - Université Paris 7, 75005 Paris, France PCC - Collège de France, 75005 Paris, France
    e-mail: [melin;bartlett;delabrouille]@cdf.in2p3.fr

(Received 15 April 2004 / Accepted 11 September 2004)

Abstract
We study the nature of cluster selection in Sunyaev-Zel'dovich (SZ) surveys, focusing on single frequency observations and using Monte Carlo simulations incorporating instrumental effects, primary cosmic microwave background (CMB) anisotropies and extragalactic point sources. Clusters are extracted from simulated maps with an optimal, multi-scale matched filter. We introduce a general definition for the survey selection function that provides a useful link between an observational catalog and theoretical predictions. The selection function defined over the observed quantities of flux and angular size is independent of cluster physics and cosmology, and thus provides a useful characterization of a survey. Selection expressed in terms of cluster mass and redshift, on the other hand, depends on both cosmology and cluster physics. We demonstrate that SZ catalogs are not simply flux limited, and illustrate how incorrect modeling of the selection function leads to biased estimates of cosmological parameters. The fact that SZ catalogs are not flux limited complicates survey "calibration" by requiring more detailed information on the relation between cluster observables and cluster mass.

Key words: cosmology: large-scale structure of Universe -- galaxies: clusters: general

© ESO 2004

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