标题： 一种新的观测与模拟透镜星系匹配策略 显示英文标题

标题： A new strategy for matching observed and simulated lensing galaxies

摘要： 强引力透镜系统的传统研究方法通常涉及构建一个能够重现观测到的多重成像特性的质量分布。然而，这种质量重建通常是非唯一的。在此，我们提出了一种替代策略：不是去模拟质量分布，而是从宇宙学星系形成模拟中寻找可能的匹配。本文在SLACS巡天中的七个研究得很好的透镜系统上测试了这个想法。对于每个系统，我们首先使用预期的爱因斯坦半径作为初步标准，在EAGLE模拟中预先选择几百个星系。然后，对于每个预先选定的星系，我们通过MCMC方法拟合透镜星系的位置和方向，并同时拟合源的光度分布，以重现多个图像和弧。结果显示，该策略是可行的，并且甚至可以得出两种不同星系形成场景的相对后验概率，尽管这些概率目前还不具有统计显著性。将此方法扩展到其他可观测量（例如透镜星系中恒星群体的运动学和颜色）原则上是直接的，但我们尚未尝试。扩展到任意大量的透镜系统似乎也是可行的。这对于即将到来的大范围巡天尤其重要，因为这些巡天可能会使星系透镜的数量增加可能百倍，从而压倒传统的建模方法。 显示英文摘要

摘要： The study of strong-lensing systems conventionally involves constructing a mass distribution that can reproduce the observed multiply-imaging properties. Such mass reconstructions are generically non-unique. Here, we present an alternative strategy: instead of modelling the mass distribution, we search cosmological galaxy-formation simulations for plausible matches. In this paper we test the idea on seven well-studied lenses from the SLACS survey. For each of these, we first pre-select a few hundred galaxies from the EAGLE simulations, using the expected Einstein radius as an initial criterion. Then, for each of these pre-selected galaxies, we fit for the source light distribution, while using MCMC for the placement and orientation of the lensing galaxy, so as to reproduce the multiple images and arcs. The results indicate that the strategy is feasible, and even yields relative posterior probabilities of two different galaxy-formation scenarios, though these are not statistically significant yet. Extensions to other observables, such as kinematics and colours of the stellar population in the lensing galaxy, is straightforward in principle, though we have not attempted it yet. Scaling to arbitrarily large numbers of lenses also appears feasible. This will be especially relevant for upcoming wide-field surveys, through which the number of galaxy lenses will rise possibly a hundredfold, which will overwhelm conventional modelling methods.