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arXiv 1208.6010astro-ph.CO
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强透镜的两个精确的时间延迟距离:对宇宙学的意义

Two accurate time-delay distances from strong lensing: Implications for cosmology

S. H. Suyu, M. W. Auger, S. Hilbert, P. J. Marshall, M. Tewes, T. Treu, C. D. Fassnacht, L. V. E. Koopmans, D. Sluse, R. D. Blandford, F. Courbin, G. Meylan

摘要:

强引力透镜在多个图像和透镜质量分布模型之间具有测量的时间延迟,允许一步确定时间延迟距离,从而测量宇宙学参数。本文对RXJ 1131 -1231引力透镜进行了盲态分析,其中包括:(1)新测量的COSMOGRAIL的时间延迟,(2)透镜系统的HST存档图像,(3)基于Keck光谱学的透镜星系速度色散测量值为323+/-20km/s,以及(4)通过观察透镜的环境和通过Millennium Simulation进行的光线追踪来表征视线结构。我们的盲分析旨在防止实验者的偏见。对数据集的联合分析允许延时距离测量达到6%的精度,并考虑到所有已知的系统不确定性。结合WMAP 7平wCDM宇宙学数据,我们得到RXJ 1131 -1231的非盲宇宙学约束为:H_0=80.0+5.8/-5.7km/s/Mpc,OmegaDE=0.79+/-0.03和w=-1.25+0.17/-0.21。我们发现这些结果与引力透镜B1608+656的分析结果在统计上是一致的。两个透镜和WMAP 7的联合约束条件为:在平坦wCDM中,H_0=75.2+4.4/-4.2km/s/Mpc,OmegaDE=0.76+0.02/-0.03和w=-1.14+0.17/-0.20;在开放式LCDM中,OmegaL=0.75+0.01/-0.02和OmegaK=0.003+0.005/-0.006。时间延迟透镜特别严格地限制了哈勃常数(在wCDM和开放LCDM中分别为5.7%和4.0%)和宇宙曲率。它们很好地补充了其他宇宙学探测器,并为未知的系统学提供了独立的检查。我们对哈勃常数的测量完全独立于基于局部距离阶梯方法的测量,这为标准宇宙学模型和广义相对论提供了重要的一致性检验。

英文摘要:

Strong gravitational lenses with measured time delays between the multiple images and models of the lens mass distribution allow a one-step determination of the time-delay distance, and thus a measure of cosmological parameters. We present a blind analysis of the gravitational lens RXJ1131-1231 incorporating (1) the newly measured time delays from COSMOGRAIL, (2) archival HST imaging of the lens system, (3) a new velocity-dispersion measurement of the lens galaxy of 323+/-20km/s based on Keck spectroscopy, and (4) a characterization of the line-of-sight structures via observations of the lens' environment and ray tracing through the Millennium Simulation. Our blind analysis is designed to prevent experimenter bias. The joint analysis of the data sets allows a time-delay distance measurement to 6% precision that takes into account all known systematic uncertainties. In combination with the WMAP7 data set in flat wCDM cosmology, our unblinded cosmological constraints for RXJ1131-1231 are: H_0=80.0+5.8/-5.7km/s/Mpc, OmegaDE=0.79+/-0.03 and w=-1.25+0.17/-0.21. We find the results to be statistically consistent with those from the analysis of the gravitational lens B1608+656. The joint constraints from the two lenses and WMAP7 are H_0=75.2+4.4/-4.2km/s/Mpc, OmegaDE=0.76+0.02/-0.03 and w=-1.14+0.17/-0.20 in flat wCDM, and H_0=73.1+2.4/-3.6km/s/Mpc, OmegaL=0.75+0.01/-0.02 and OmegaK=0.003+0.005/-0.006 in open LCDM. Time-delay lenses constrain especially tightly the Hubble constant (5.7% and 4.0% respectively in wCDM and open LCDM) and curvature of the universe. They complement well other cosmological probes, and provide an independent check of unknown systematics. Our measurement of the Hubble constant is completely independent of those based on the local distance ladder method, providing an important consistency check of the standard cosmological model and of general relativity.

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