Abstract
We construct a high-resolution mass map of the z=0.39 cluster 0024+1654, based on a parametric inversion of the associated gravitational lens. The lens creates eight well-resolved subimages 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 35 h-1 kpc soft core. The asymmetry in the mass distribution is less than 3% inside 107 h-1 kpc radius. The dark matter distribution we observe in CL 0024 is far more smooth, symmetric, and nonsingular than in typical simulated clusters in either Ω=1 or Ω=0.3 cold dark matter cosmologies. Integrated to a 107 h-1 kpc radius, the rest-frame mass-to-light ratio is M/LV=276±40 h (M/LV)☉.
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