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第1419回 天文学教室談話会

日時

2015年6月30日(火) 13:30

場所

合同A棟 第3講義室 205号室

講演者

梅津 敬一(ASIAA)

題目

The Full Strength of Cluster Gravitational Lensing: Mass distribution in and around Cosmic Giants from the CLASH Survey

要旨


CLASH is a Hubble Multi-Cycle Treasury program that has been designed to probe the mass distribution of 25 galaxy clusters. In this talk, I will present new results (Umetsu et al., to be submitted in 2 weeks) from a full-lensing analysis of a sample of 20 clusters in the CLASH survey. Our analysis combines constraints from 16-band Hubble Space Telescope observations (Zitrin et al. 2015) and wide-field multi-color imaging (Umetsu et al. 2014) taken primarily with Suprime-Cam on the Subaru Telescope. We reconstruct ????projected mass density profiles of individual clusters from a joint likelihood analysis of strong-lensing, weak-lensing shear and magnification measurements, and determine masses and concentrations for all clusters. We find internal consistency of the ensemble mass calibration to be < (5 +/- 6) percent in the one-halo regime 200-2000kpc/h, by comparison with the CLASH weak-lensing-only measurements of Umetsu et al. (2014). We show that the halo concentration-mass relation obtained for the X-ray-selected, lensing-unbiased subsample is in excellent agreement with LCDM predictions when the CLASH selection function based on X-ray morphological regularity and the projection effects are taken into account. The ensemble-averaged mass profile of the X-ray-selected subsample is detected at 33-sigma significance over the range <4000kpc/h and well described by a family of density profiles predicted for cuspy dark-matter-dominated halos in gravitational equilibrium, namely the Navarro-Frenk-White, Einasto, and DARKexp models, whereas the single power-law, cored isothermal and Burkert density profiles are disfavored by the data. We show that cuspy halo models that include the large-scale two-halo term provide improved agreement with the data.

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【The Colloquium Committee in 2015】
Kenji Toma (toma<at>astr.tohoku.ac.jp)
Yurina Mizuno
Kohei Miyazawa
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