A Hubble Space Telescope Lensing Survey of X-Ray Luminous Galaxy Clusters. I. A383

Abstract

We present an analysis of the mass distribution in the core of A383 (z=0.188), one of 12 X-ray luminous galaxy clusters at z~0.2 selected for a comprehensive and unbiased study of the mass distribution in massive galaxy clusters. Deep optical imaging performed by the Hubble Space Telescope (HST) reveals a wide variety of gravitationally lensed features in the core of A383, including a giant arc, two radial arcs in the halo of the central cluster galaxy, several multiply imaged arcs, and numerous arclets. Based upon the constraints from the various lensed features, we construct a detailed model of the mass distribution in the central regions of the cluster, taking into account both a cluster-scale potential and perturbations from individual cluster galaxies. Keck spectroscopy of one component of the giant arc identifies it as an image of a star-forming galaxy at z=1.01 and provides an accurate measurement of the mass of the cluster within the projected radius of the giant arc (65 kpc) of (3.5+/-0.1)×10¹³ M_solar. Using the weak shear measured from our HST observations, we extend our mass model to larger scales and determine a mass of (1.8+/-0.2)×10¹⁴ M_solar within a radius of 250 kpc. On smaller scales we use the radial arcs to probe the shape of the total mass distribution in the cluster core (r<~20 kpc) and find that the density profile is more peaked than a single Navarro, Frenk, & White (NFW) dark matter profile. Our findings imply that the dark matter in A383 may be more steeply peaked than NFW predict and that the cD galaxy measurably perturbs the cluster potential well. The optical and X-ray properties of A383 indicate the presence of a central cooling flow, for which we derive a mass deposition rate of >~200 M_solar yr^-1. We also use the X-ray emission from A383 to obtain independent estimates of the total mass within projected radii of 65 and 250 kpc: (4.0^+1.1_-1.7)×10¹³ and (1.2+/-0.5)×10¹⁴ M_solar, which are consistent with the lensing measurements. Based on observations with the NASA/ESA Hubble Space Telescope obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.