Detailed Mass Map of CL 0024+1654 from Strong Lensing

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.1 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/L_V=276+/-40 h (M/L_V)_solar.