Analytic Time Delays and H0 Estimates for Gravitational Lenses
Analytic Time Delays and H0 Estimates for Gravitational Lenses
复制标题
DOI：
10.1086/317201
复制
发表时间：
2000-04
期刊：
影响因子：
--
通讯作者：
H. Witt;S. Mao;C. Keeton
中科院分区：
文献类型：
--
作者：
H. Witt;S. Mao;C. Keeton
我们研究了一类广义的透镜势族的引力透镜时间延迟，其中包括常见的奇异等温椭圆势族和奇异等温椭圆密度分布族，但允许一般的角结构。使用一种新颖的方法，我们证明了时间延迟可以以一种非常简单的形式投射，仅取决于观察到的图像位置。加入外部剪切使时间延迟与抗剪强度成正比，而改变电势的径向分布将使时间延迟大致呈线性变化。这些分析结果可以用来获得观测到的引力透镜的时间延迟和哈勃常数的简单估计。对5个延时透镜中的4个的朴素估计显示出彼此之间以及与H0的局部测量值惊人的一致；复杂的Q0957+561星系是唯一的例外。这一一致表明，使用简单的等温透镜模型来推断H0是合理的，尽管通过检查详细的模型和测量更多的透镜时间延迟来验证这一结论仍然很重要。
We study gravitational lens time delays for a general family of lensing potentials, which includes the popular singular isothermal elliptical potential and singular isothermal elliptical density distribution but allows general angular structure. Using a novel approach, we show that the time delay can be cast in a very simple form, depending only on the observed image positions. Including an external shear changes the time delay in proportion to the shear strength, and varying the radial profile of the potential changes the time delay approximately linearly. These analytic results can be used to obtain simple estimates of the time delay and the Hubble constant in observed gravitational lenses. The naive estimates for four of five time delay lenses show surprising agreement with each other and with local measurements of H0; the complicated Q0957+561 system is the only outlier. The agreement suggests that it is reasonable to use simple isothermal lens models to infer H0, although it is still important to check this conclusion by examining detailed models and by measuring more lensing time delays.