arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0910.2773astro-ph.CO
收藏

解剖引力透镜B1608 +656。II。哈勃常数、空间曲率和暗能量状态方程的精确测量

Dissecting the Gravitational Lens B1608+656. II. Precision Measurements of the Hubble Constant, Spatial Curvature, and the Dark Energy Equation of State

S. H. Suyu, P. J. Marshall, M. W. Auger, S. Hilbert, R. D. Blandford, L. V. E. Koopmans, C. D. Fassnacht, T. Treu

摘要:

强引力透镜系统在多个图像之间具有测量的时间延迟,提供了测量透镜的“时间延迟距离”的方法,从而测量哈勃常数。我们提出了一个强引力透镜系统B1608+656的贝叶斯分析,结合(i)新的,深哈勃太空望远镜(HST)的观测,(ii)一个新的速度色散测量260+/-15公里/秒的主透镜星系,和(iii)透镜的环境的最新研究。在模拟主透镜星系的恒星动力学、透镜效应和透镜环境时,我们明确地包括了总质量分布轮廓对数斜率γ '和外部收敛kappa_ext;我们边缘化这些参数,为它们分配动机良好的先验,从而将主要的系统误差转化为统计误差。HST图像提供了一个这样的先验,将晶状体质量密度分布对数斜率约束为γ '= 2.08+/-0.03; B1608+656场的数值模拟和光度观测的组合提供了kappa_ext的先验估计:0.10 + 0.08/-0.05。后一种分布支配着H_0的最终不确定性。与以前的工作相比,这个系统,新的数据提供了一个以上的两个因素的精度增加。结合WMAP的5年数据集,我们发现B1608+656数据集将曲率参数限制在-0.031 < Omega_k < 0.009(95% CL),这一精度水平与当前Ia型超新星样本所提供的精度相当。我们发现,结合WMAP,H_0 = 69.7 + 4.9/-5.0 km/s/Mpc,w=-0.94 +0.17/-0.19(68%CL),这表明B1608+656的观测结果和当前的重子声学振荡数据一样严格地限制了w。(节略)

英文摘要:

Strong gravitational lens systems with measured time delays between the multiple images provide a method for measuring the "time-delay distance" to the lens, and thus the Hubble constant. We present a Bayesian analysis of the strong gravitational lens system B1608+656, incorporating (i) new, deep Hubble Space Telescope (HST) observations, (ii) a new velocity dispersion measurement of 260+/-15 km/s for the primary lens galaxy, and (iii) an updated study of the lens' environment. When modeling the stellar dynamics of the primary lens galaxy, the lensing effect, and the environment of the lens, we explicitly include the total mass distribution profile logarithmic slope gamma' and the external convergence kappa_ext; we marginalize over these parameters, assigning well-motivated priors for them, and so turn the major systematic errors into statistical ones. The HST images provide one such prior, constraining the lens mass density profile logarithmic slope to be gamma'=2.08+/-0.03; a combination of numerical simulations and photometric observations of the B1608+656 field provides an estimate of the prior for kappa_ext: 0.10 +0.08/-0.05. This latter distribution dominates the final uncertainty on H_0. Compared with previous work on this system, the new data provide an increase in precision of more than a factor of two. In combination with the WMAP 5-year data set, we find that the B1608+656 data set constrains the curvature parameter to be -0.031 < Omega_k < 0.009 (95% CL), a level of precision comparable to that afforded by the current Type Ia SNe sample. Asserting a flat spatial geometry, we find that, in combination with WMAP, H_0 = 69.7 +4.9/-5.0 km/s/Mpc and w=-0.94 +0.17/-0.19 (68% CL), suggesting that the observations of B1608+656 constrain w as tightly as do the current Baryon Acoustic Oscillation data. (abridged)

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑