Evidence for substructure in lens galaxies
Evidence for substructure in lens galaxies
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DOI：
10.1046/j.1365-8711.1998.01319.x
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发表时间：
1997-07
影响因子：
4.8
通讯作者：
S. Mao;P. Schneider
中科院分区：
文献类型：
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作者：
S. Mao;P. Schneider
我们讨论是否应该期望可以通过仅包含几个参数的“简单”透镜模型来理解多重成像 QSO。尽管对于许多透镜系统来说，这种简单的质量模型可以很好地描述所观察到的特性，但有些系统却很难定量地理解。我们认为，至少在一种情况下（B 1422+231），这些困难并不是（仅仅）由于透镜模型的“错误”参数化造成的，而是观察到的通量比与模型预测的通量比之间的差异是由于透镜的子结构造成的。与光通量的微透镜一样，这种子结构也会扭曲“简单”质量模型预测的无线电通量比，特别是对于高度放大的图像，而不会明显改变图像位置。子结构也不会显着改变时间延迟，因此对利用时间延迟确定哈勃常数影响不大。我们用几个简单的子结构场景来量化这些陈述，并提出了一种对怀疑有子结构的镜头系统进行建模的策略。
We discuss whether one should expect that multiply imaged QSOs can be understood with ‘simple’ lens models that contain only a few parameters. Whereas for many lens systems such simple mass models yield a remarkably good description of the observed properties, there are some systems which are notoriously difficult to understand quantitatively. We argue that at least in one case (B 1422+231) these difficulties are not (solely) due to a ‘wrong’ parametrization of the lens model, but that the discrepancy between observed and model-predicted flux ratios is due to substructure in the lens. As in microlensing for optical fluxes, such substructure can distort also the radio flux ratios predicted by ‘simple’ mass models, in particular for highly magnified images, without appreciably changing image positions. Substructure also does not change the time delay significantly, and therefore has little effect on the determination of the Hubble constant using time delays. We quantify these statements with several simple scenarios for substructure, and propose a strategy to model lens systems in which substructure is suspected.