Detailed Mass Map of CL0024+1654 from Strong Lensing

We construct a high resolution mass map of the z = 0.39 cluster 0024+1654, based on parametric inversion of the associated gravitational lens. The lens creates eight well-resolved sub-images of a background galaxy, seen in deep imaging with the Hubble Space Telescope. Excluding mass concentrations centered on visible galaxies, more than 98% of the remaining mass is represented by a smooth concentration of dark matter centered near the brightest cluster galaxies, with a 33 h kpc soft core. The asymmetry in the mass distribution is <3% inside 107 h kpc radius. The dark matter distribution we observe in CL0024 is far more smooth, symmetric, and nonsingular than in typical simulated clusters in either Ω = 1 or Ω = 0.3 CDM cosmologies. Integrated to 107 h kpc radius, the rest-frame mass to light ratio is M/LV = 238± 40 h (M/LV )⊙. Subject headings: gravitational lensing — cosmology: observations — methods: observational — galaxies: cluster, individual (CL0024+1654) — galaxies: formation — dark matter Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, under NASA contract NAS 5-26555