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arXiv 0911.2471astro-ph.CO
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Sloan Lens ACS调查。IX。早型星系的颜色、透镜和恒星质量

The Sloan Lens ACS Survey. IX. Colors, Lensing and Stellar Masses of Early-type Galaxies

M. W. Auger, T. Treu, A. S. Bolton, R. Gavazzi, L. V. E. Koopmans, P. J. Marshall, K. Bundy, L. A. Moustakas

摘要:

我们目前的光度数据集的斯隆镜头ACS(SLACS)调查,包括HST光度从ACS,WFPC 2,和NICMOS。这些数据使得能够确认另外15个等级“A”(某些)镜片系统,使SLACS等级“A”镜片的数量达到85个;包括13个等级“B”(可能)系统,SLACS已经确定了近100个镜片和候选镜片。大约80%的“A”级系统具有椭圆形形态,而~10%显示螺旋结构;其余透镜具有透镜状形态。透镜和光源的光谱红移可用于每个系统,使SLACS成为迄今为止最大的星系尺度透镜均匀数据集。我们开发了一个新的贝叶斯恒星星族分析代码,以确定可靠的恒星质量与准确的误差估计。我们应用此代码深,高分辨率的HST成像和确定恒星质量与典型的统计误差为0.1德克斯,我们发现,这些恒星质量是无偏的估计相比,使用SDSS测光,提供信息的先验。恒星质量范围为10^10.5到10^11.8 M $_\odot$,在爱因斯坦半径内的典型恒星质量分数为0.4,假设是夏布里耶IMF。SLACS透镜星系的系综性质,例如恒星质量和投影椭圆率,似乎与其他具有类似恒星速度色散的SDSS星系无法区分。这进一步支持了SLACS透镜代表了M* >~ 10 ^11 M $_\odot$的大质量早型星系的总体,因此是研究z ~ 0.5星系中发光物质和暗物质的kpc尺度分布的理想数据集。

英文摘要:

We present the current photometric dataset for the Sloan Lens ACS (SLACS) Survey, including HST photometry from ACS, WFPC2, and NICMOS. These data have enabled the confirmation of an additional 15 grade `A' (certain) lens systems, bringing the number of SLACS grade `A' lenses to 85; including 13 grade `B' (likely) systems, SLACS has identified nearly 100 lenses and lens candidates. Approximately 80% of the grade `A' systems have elliptical morphologies while ~10% show spiral structure; the remaining lenses have lenticular morphologies. Spectroscopic redshifts for the lens and source are available for every system, making SLACS the largest homogeneous dataset of galaxy-scale lenses to date. We have developed a novel Bayesian stellar population analysis code to determine robust stellar masses with accurate error estimates. We apply this code to deep, high-resolution HST imaging and determine stellar masses with typical statistical errors of 0.1 dex; we find that these stellar masses are unbiased compared to estimates obtained using SDSS photometry, provided that informative priors are used. The stellar masses range from 10^10.5 to 10^11.8 M$_\odot$ and the typical stellar mass fraction within the Einstein radius is 0.4, assuming a Chabrier IMF. The ensemble properties of the SLACS lens galaxies, e.g. stellar masses and projected ellipticities, appear to be indistinguishable from other SDSS galaxies with similar stellar velocity dispersions. This further supports that SLACS lenses are representative of the overall population of massive early-type galaxies with M* >~ 10^11 M$_\odot$, and are therefore an ideal dataset to investigate the kpc-scale distribution of luminous and dark matter in galaxies out to z ~ 0.5.

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