Source-position transformation: an approximate invariance in strong gravitational lensing
Source-position transformation: an approximate invariance in strong gravitational lensing
复制标题
源位置变换：强引力透镜中的近似不变性
DOI：
10.1051/0004-6361/201322106
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发表时间：
2014
影响因子：
6.5
通讯作者：
D. Sluse
中科院分区：
文献类型：
--
作者：
P. Schneider;D. Sluse
引力透镜在确定偏转器的精确质量或确定哈勃常数的精确估计时的主要障碍是透镜观测量相对于质量片变换（MST）的简并性。MST是质量分布的全局修改，其使所有图像位置、形状和通量比不变，但其改变时间延迟。在这里，我们表明，另一个全球性的变换的透镜质量分布存在的叶图像的位置和通量比几乎不变，其中MST是一个特例。与MST的情况一样，这种新的变换仅适用于仅考虑与我们距离相同的源分量的情况。而对于轴对称透镜，这种源位置变换精确地再现了所有强透镜观测量，它只近似地用于更一般的透镜情况。我们提供粗估计的准确性，变换后的质量分布可以重现相同的图像位置作为原始透镜模型，并提出了一个说明性的例子，其性能。这种新的不变性变换很可能是为什么相同的强透镜信息可以用相当不同的质量模型来解释的原因。
The main obstacle that gravitational lensing has in determining accurate masses of deflectors, or in determining precise estimates for the Hubble constant, is the degeneracy of lensing observables with respect to the mass-sheet transformation (MST). The MST is a global modification of the mass distribution which leaves all image positions, shapes, and flux ratios invariant, but which changes the time delay. Here we show that another global transformation of lensing mass distributions exists which leaves image positions and flux ratios almost invariant, and of which the MST is a special case. As is the case for the MST, this new transformation only applies if one considers only those source components that are at the same distance from us. Whereas for axi-symmetric lenses this source position transformation exactly reproduces all strong lensing observables, it does so only approximately for more general lens situations. We provide crude estimates for the accuracy with which the transformed mass distribution can reproduce the same image positions as the original lens model, and present an illustrative example of its performance. This new invariance transformation is most likely the reason why the same strong lensing information can be accounted for with rather different mass models.