演講資訊

摘要：

Clusters of galaxies, the largest gravitationally bound objects formed in the universe, play a fundamental role in our understanding of cosmology and structure formation. I will present results from a comprehensive strong-lensing, weak-lensing shear and magnification analysis of a sample of 20 high-mass clusters targeted in the CLASH survey. Our analysis combines high-quality data from 16-band HST observations and wide-field multi-color imaging taken primarily with Subaru/Suprime-Cam. We reconstruct projected mass density profiles of individual clusters from a joint analysis of the full lensing constraints, and determine their halo masses and concentrations. We show that the observed halo concentration-mass relation is in excellent agreement with theoretical predictions when the CLASH selection function and projection effects are accounted for. We also derive an ensemble-averaged projected density profile of the clusters by stacking their individual profiles. The stacked lensing signal is remarkably well described by density profiles predicted for cuspy dark-matter-dominated halos in gravitational equilibrium, namely, the NFW, Einasto, and DARK-exp models. We show that cuspy halo models that include the large-scale 2-halo term provide improved agreement with the data. Finally, we develop a new method optimized for an extraction of local density features such as the splashback radius (Rsp), a sharp halo edge corresponding to the outermost caustic in accreting halos, and apply it to our CLASH lensing data. Assuming the profile form of Diemer & Kravtsov (2014) and priors calibrated from numerical simulations, we place a lower limit on the splashback radius, if it exists, to be Rsp/R200m > 0.85 (Rsp > 1.74Mpc/h) at 68%CL.