Weak Lensing Analysis of the z ≃ 0 . 8 cluster CL 0152 - 1357 with the Advanced Camera for Surveys

We present a weak lensing analysis of the X-ray luminous cluster CL 0152-1357 at z ≃ 0.84 using HST/ACS observations. The unparalleled resolution and sensitivity of ACS enable us to measure weakly distorted, faint background galaxies to the extent that the number density reaches ∼ 175 arcmin −2. The PSF of ACS has a complicated shape that also varies across the field. We construct a PSF model for ACS from an extensive investigation of 47 Tuc stars in a modestly crowded region. We show that this model PSF excellently describes the PSF variation pattern in the cluster observation when a slight adjustment of ellipticity is applied. The high number density of source galaxies and the accurate removal of the PSF effect through moment-based deconvolution allow us to restore the dark matter distribution of the cluster in great detail. The direct comparison of the mass map with the X-ray morphology from Chandra observations shows that the two peaks of intracluster medium traced by X-ray emission are lagging behind the corresponding dark matter clumps, indicative of an ongoing merger. The overall mass profile of the cluster can be well described by an NFW profile with a scale radius of r s = 309 ± 45 kpc and a concentration parameter of c = 3.7 ± 0.5. The mass estimates from the lensing analysis are consistent with those from X-ray and Sunyaev-Zeldovich analyses. The predicted velocity dispersion is also in good agreement with the spectroscopic measurement from VLT observations. In the adopted cosmology where Ω M = 0.27, Ω Λ = 0.73, and h = 0.71, the total projected mass and the mass-to-light ratio within 1 Mpc are estimated to be (4.92 ± 0.44)×10 14 M ⊙ and 95 ± 8 M ⊙ /L B⊙ , respectively.