arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1904.07239astro-ph.CO
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强引力透镜的广义模型独立表征VI:形式主义固有简并的起源及其对$H_0$的影响

Generalised model-independent characterisation of strong gravitational lenses VI: the origin of the formalism intrinsic degeneracies and their influence on $H_0$

Jenny Wagner

摘要:

我们给出一个物理解释的形式主义内在退化的引力透镜形式主义,我们推导出的数学基础上的第四部分,这一系列。我们发现,所有简并的发生都是由于质量密度沿视线的分配。通常,它被划分为背景(宇宙)密度和前景偏转对象。后者可以进一步分为一个主要的偏转对象和扰动。沿着视线的弱偏转物体也被添加到偏转物体或作为角直径距离的校正,扰动宇宙学背景密度。先验地,这是参考系和分区的任意选择。它们可以在不改变透镜观测量的情况下重新定义,透镜观测量对沿整个视线的积分偏转质量密度敏感。重新制定的时间延迟方程,使这种解释的简并变得很容易看到,我们注意到,源可以从这个公式中删除,这简化了重建的偏转质量分布或哈勃常数,$H_0$的推断。随后,我们列出了打破形式主义内在简并的必要条件,并讨论了通过模型选择或包括非透镜观测量(如沿视线的速度色散)来打破它们的方法及其优缺点。最后,我们系统地总结了所有形式主义的内在退化和打破它们的可能性。

英文摘要:

We give a physical interpretation of the formalism intrinsic degeneracies of the gravitational lensing formalism that we derived on a mathematical basis in part IV of this series. We find that all degeneracies occur due to the partition of the mass density along the line of sight. Usually, it is partitioned into a background (cosmic) density and a foreground deflecting object. The latter can be further partitioned into a main deflecting object and perturbers. Weak deflecting objects along the line of sight are also added, either to the deflecting object or as a correction of the angular diameter distances, perturbing the cosmological background density. A priori, this is an arbitrary choice of reference frame and partition. They can be redefined without changing the lensing observables which are sensitive to the integrated deflecting mass density along the entire line of sight. Reformulating the time delay equation such that this interpretation of the degeneracies becomes easily visible, we note that the source can be eliminated from this formulation, which simplifies reconstructions of the deflecting mass distribution or the inference of the Hubble constant, $H_0$. Subsequently, we list necessary conditions to break the formalism intrinsic degeneracies and discuss ways to break them by model choices or including non-lensing observables like velocity dispersions along the line of sight with their advantages and disadvantages. We conclude with a systematic summary of all formalism intrinsic degeneracies and possibilities to break them.

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