Detailed lensing properties of the MS 2137-2353 core and reconstruction of sources from Hubble Space Telescope imagery

A deep HST image of the core of the cluster of galaxies MS 2137-2353 has revealed detailed morphological structures in two are systems, which are modeled and well reproduced. An analysis of the lensing properties of the dark matter component indicates that the cluster could have a mass distribution almost as simple as a single elliptical mass distribution, with ellipticity and angular orientation similar to those in visible and X-ray light. This suggests that MS 2137-2353 is a relaxed cluster at z = 0.313. The predicted density profile (rho similar to r(-1.75+/-0.09), with r(c) less than or equal to 17 h(50)(-1) kpc) within 150 h(50)(-1) kpc, implies a M/L ratio increasing with the radius, and could be in agreement with predictions from standard CDM simulations. Two faint sources (unlensed magnitude R = 23.5 and 25.6) at the same redshift are aligned with the cluster core and are responsible for the are systems. They have been reconstructed with details as small as 0." 015 (or 120 h(50)(-1) pc in the source assumed at z = 1), and show complex morphology, which for one source could be related to a close interacting pair and/or to dust. They also show strong signs of star formation, indicated by compact H II regions away from their centers. Because magnification factors of the giant luminous are are large, our method can even resolve the size of a giant H II region at z similar to 1.