| Abstract
| - We have detected the weak lensing signal induced by the cluster of galaxies MS 2053−04 (z=0.58) from a two-colour mosaic of six Hubble Space Telescope (HST) WFPC2 images. The best-fitting singular isothermal sphere model to the observed tangential distortion yields an Einstein radius rE=6.2±1.8 arcsec, which corresponds to a velocity dispersion of (Ωm=0.3, ΩΛ=0.0). This result is in good agreement with the observed velocity dispersion of 817±80 km s-1 from cluster members. The observed average rest-frame mass-to-light ratio within a radius aperture is 184±56 h50 M⊙/LB⊙. After correction for luminosity evolution to z=0, this value changes to 291±89±19 h50 M⊙/LB⊙ (where the first error indicates the statistical uncertainty in the measurement of the mass-to-light ratio, and the second error is due to the uncertainty in luminosity evolution). MS 2053 is the third cluster we have studied using mosaics of deep WFPC2 images. For all three clusters we find good agreement between dynamical and weak lensing velocity dispersions, in contrast to weak lensing studies based on single WFPC2 pointings on cluster cores. This result demonstrates the importance of wide-field data. We have compared the ensemble-averaged cluster profile of the clusters in our sample with the predicted Navarro, Frenk & White (NFW) profile, and find that an NFW profile can fit the observed lensing signal well. The best-fitting concentration parameter is found to be (68 per cent confidence) times the predicted value from an open cold dark matter (CDM) model. The observed mass-to-light ratios of the clusters in our sample evolve with redshift, and are inconsistent with a constant, non-evolving, mass-to-light ratio at the 99 per cent confidence level. The evolution is consistent with the results derived from the evolution of the fundamental plane of early-type galaxies. The resulting average mass-to-light ratio for massive clusters at z=0 is found to be 239±18±9 h50 M⊙/LB⊙.
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