A Lensing Survey of X-ray Luminous Galaxy Clusters at Redshift z ~ 0.2: II: CFH12k weak lensing imaging and cluster sample analysis

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  • 15 March 2007
Abstract
We present a wide-field multi-color survey of a homogeneous sample of clusters of 11 galaxies aimed at measuring their total masses and their mass distribution from weak lensing. The 11 clusters in our sample are all X-ray luminous and span a narrow redshift range at z=0.21 +/- 0.04. The weak lensing analysis of the sample is based on the methodology developped and applied recently on the massive cluster Abell 1689, with some improved features in the selection of the galaxy catalogs. We use a Bayesian method, implemented in the Im2shape software to fit the shape parameters of the faint galaxies and to correct for PSF smearing. A multi-color selection of the background galaxies is applied to retrieve the weak lensing signal, reducing the background density of sources to 10 to 15 galaxies per square arcminute. With the present data, shear profiles are measured in each cluster up to at least 2 Mpc (more than 15' from the center) and are fitted with parametric mass profiles. The virial mass M_200 is estimated for each cluster and then compared to other physical properties. Results: Scaling relations between mass and optical luminosity indicate an increase of the M/L ratio with luminosity (M/L \propto L^0.8) while the normalisation of the M_200 \propto T_X^{3/2} relation is close to the one expected from hydrodynamical simulations of cluster formation. We discuss the scatter in the M_200-T_X and M_200-L_X relations and claim that the dispersion may underline the different cluster (merging) histories for clusters of similar measured masses and intrinsic variations in the X-ray properties of clusters of similar optical and mass properties.

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