Weak‐Lensing Analysis of thez ≃ 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 0152-1357at z~0.84 using HST/ACS observations. The unparalleled resolution andsensitivity of ACS enable us to measure weakly distorted, faint backgroundgalaxies to the extent that the number density reaches ~175 arcmin^-2. The PSFof ACS has a complicated shape that also varies across the field. We constructa PSF model for ACS from an extensive investigation of 47 Tuc stars in amodestly crowded region. We show that this model PSF excellently describes thePSF variation pattern in the cluster observation when a slight adjustment ofellipticity is applied. The high number density of source galaxies and theaccurate removal of the PSF effect through moment-based deconvolution allow usto restore the dark matter distribution of the cluster in great detail. Thedirect comparison of the mass map with the X-ray morphology from Chandraobservations shows that the two peaks of intracluster medium traced by X-rayemission are lagging behind the corresponding dark matter clumps, indicative ofan on-going merger. The overall mass profile of the cluster can be welldescribed by an NFW profile with a scale radius of r_s =309+-45 kpc and aconcentration parameter of c=3.7+-0.5. The mass estimates from the lensinganalysis are consistent with those from X-ray and Sunyaev-Zeldovich analyses.The predicted velocity dispersion is also in good agreement with thespectroscopic measurement from VLT observations. In the adopted WMAP cosmology,the total projected mass and the mass-to-light ratio within 1 Mpc are estimatedto be 4.92+-0.44 10^14 solar mass and 95+-8 solar mass/solar luminosity,respectively.