The galaxy cluster Y_SZ−L_X and Y_SZ−M relations from the WMAP 5-yr data

¹ DSM/Irfu/SPP, CEA/Saclay, 91191 Gif-sur-Yvette Cedex, France
e-mail: jean-baptiste.melin@cea.fr
² APC – Université Paris Diderot, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France
e-mail: bartlett@apc.univ-paris7.fr
³ APC – CNRS, 10 rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France
e-mail: delabrouille@apc.univ-paris7.fr
⁴ DSM/Irfu/SAp, CEA/Saclay, 91191 Gif-sur-Yvette Cedex, France
e-mail: monique.arnaud@cea.fr; rocco.piffaretti@cea.fr; gabriel.pratt@cea.fr

Received: 6 January 2010
Accepted: 21 October 2010

Abstract

We use multifrequency matched filters to estimate, in the WMAP 5-year data, the Sunyaev-Zel’dovich (SZ) fluxes of 893 ROSAT NORAS/REFLEX clusters spanning the luminosity range L_{X,[0.1−2.4]   keV} = 2 × 10⁴¹−3.5 × 10⁴⁵ erg s^-1. The filters are spatially optimised by using the universal pressure profile recently obtained from combining XMM-Newton observations of the REXCESSsample and numerical simulations. Although the clusters are individually only marginally detected, we are able to firmly measure the SZ signal (>10σ) when averaging the data in luminosity/mass bins. The comparison between the bin-averaged SZ signal versus luminosity and X-ray model predictions shows excellent agreement, implying that there is no deficit in SZ signal strength relative to expectations from the X-ray properties of clusters. Using the individual cluster SZ flux measurements, we directly constrain the Y₅₀₀−L_X and Y₅₀₀−M₅₀₀ relations, where Y₅₀₀ is the Compton y-parameter integrated over a sphere of radius r₅₀₀. The Y₅₀₀−M₅₀₀ relation, derived for the first time in such a wide mass range, has a normalisation at M₅₀₀ = 3 × 10¹⁴   h^-1   M_⊙, in excellent agreement with the X-ray prediction of 1.54 × 10^-3   arcmin², and a mass exponent of α = 1.79 ± 0.17, consistent with the self-similar expectation of 5/3. Constraints on the redshift exponent are weak due to the limited redshift range of the sample, although they are compatible with self-similar evolution.