Mass and light in the supercluster of galaxies MS0302+17

International audienceWe 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 early-type members of the supercluster, and foreground ellipticals. We derive a R band catalogue of background galaxies for weak lensing analysis. We compute the correlation 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-statistic applied in regions close to cluster centers and global correlation 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 \citet{Kaiser98}. If we model dark matter halos around each early-type galaxy by a truncated isothermal sphere, we find that a linear relation M∝ L still holds. In this case, the average halo truncation radius is s* ⪉ 200 h-170kpc close to clusters cores whereas it reaches a lower limit of ˜300 h-170kpc at the periphery. This change of s* as a function of radial distance may be interpreted as a result of tidal stripping of early type galaxies. Nevertheless the lack of information on the spatial distribution of late-type galaxies affects such conclusions concerning variations of s*. Though all the data at hand are clearly consistent with the assumption that mass is faithfully traced by light from early-type galaxies, we are not able to describe in detail the contribution of late type galaxies. We however found it to be small. Forthcoming wide surveys in UV, visible, and near infrared wavelengths will provide large enough samples to extend this analysis to late-type galaxies using photometric redshifts. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT) which is operated by the National Research Council of Canada, the Institut des Sciences de l'Univers of the Centre National de la Recherche Scientifique and the University of Hawaii. Catalogue is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/422/40