Mass and Light in the Supercluster of Galaxies MS 0302 + 17 ⋆

We investigate the supercluster MS0302+17 (z ≈ 0.42) using weak lensing analysis and deep wide field BVR photometry with the CFH12K camera. Using (B-V) vs. (V-R) evolution tracks we identify supercluster early-types members and foreground ellipticals. We derive a R band background galaxies catalogue for weak lensing analysis. We compute the correlations functions of light and mass and their cross-correlation and test if light traces mass on supercluster, cluster and galaxy scales. We show that the data are consistent with this assertion. The ζ-statistics applied in regions close to cluster centers and global correlation function analyses over the whole field converge toward the simple relation M/L = 300 ± 30 h70 (M/L)⊙ in the B band. This independently confirms the earlier results obtained by Kaiser et al. (1998). We model dark matter halos around each early-type galaxy by truncated isothermal spheres and find the linear relation M ∝ L still holds. However, their averaged halo truncation radius is s * 200 h −1 70 kpc close to clusters cores, whereas it reaches a lower limit of ∼ 300 h −1 70 kpc at the periphery. This change of s * as function of radial distance may be interpreted as a result of tidal stripping on early type galaxies, but the lack of informations on the spatial distribution of the late-type galaxie sample prevents us to separate its contribution to the averaged s * we measured. Though all the data at hands are consistent with the assumption that mass is traced by light from early-type galaxies, we are not able to describe in details the contributions of late type galaxies. We however found it to be small. Forthcoming wide surveys in UV, visible and NIR wavelengths will provide large enough samples to extend this analysis to late-type galaxies using selections from galaxy color-color diagrams and photometric redshifts.