THE LENSING CLUSTER MS-0440- I - CLUSTER PROPERTIES(0204 SEEN BY HST,ROSAT, AND ASCA )

We present an analysis of the properties of the lensing cluster MS 044 0+0204 at z = 0.1965. MS 0440+0204 has been observed with a variety of telescopes at diverse wavelengths: from the ground with the Canada-Fr ance-Hawaii Telescope, the Multiple Mirror Telescope, and the Keck Tel escope, and from the Earth orbit with HST, ROSAT, and ASCA. Mass deter minations are separately obtained from galaxy virial motions and X-ray profile fitting. A simple beta model fitted to the X-ray data yields a mass of (1.3 +/- 0.2) x 10(14) M. within 583 kpc of the cluster cent er, but more general models fitted all of our data better and allow a wider range of masses that are consistent with the lensing data. In ad dition, the X-ray data yield a mass distribution profile that is well described by a beta model with a core radius of 26.7 kpc. The velocity dispersion of galaxies yields a mass of 4.8(-0.94)(+1.5) x 10(14) M. within 900 kpc. In the inner 24.'' 5 there are 24 arcs that appear to be strong gravitationally-lensed images of background sources. Models of the cluster mass distribution and its lensing properties reveal fiv e background sources at various redshifts, each forming two or more ar cs. We do not have a redshift for any are with multiple images; theref ore, we can only place upper and lower limits to the mass of the clust er from gravitational lensing. At 100 kpc, the lower limit mass from l ensing is about a factor of 2 greater than the X-ray-determined mass. The rate of increase in the projected mass at this radius is also grea ter for the lens model than the X-ray determination. To reconcile the mass estimates from the X-rays and the lensing and to try to understan d the steep slope of the gravitational lens mass, we tentatively explo re a model with a supercluster surrounding the cluster and with a mass profile that increases more rapidly than a beta model at large radii.