Weighing the Milky Way - investigating the Galactic mass distribution with the outer-halo globular clusters and their tidal tails

银河系是宇宙中唯一一个我们可以从一个独特的角度来研究的螺旋星系：从内部。因此，银河系天文学的主要研究领域只关注通过观测和理论来了解我们的家园星系。在这个研究领域，银河系内部的质量分布是观测结果和理论模型之间的重要联系。然而，银河系质量分布的测定仍然非常不确定，特别是对银河系暗晕的质量和形状的测量，它在大银河系半径处主导着质量分布。我们的目标是通过利用球状星团和它们的潮汐尾作为暗晕质量的示踪剂来测量银河系大半径范围内的质量分布。我们特别打算利用银河系外晕中的球状星团来研究银河系暗晕的形状，因为我们发现它们非常适合这一目的。我们将通过对星团及其潮汐尾的观测数据进行数值模拟，以前所未有的精度确定星团的轨道。对球状星团轨道的精确了解使我们能够直接推断出在各自星团银河系半径处的封闭质量的细节。在这种情况下，我们还将利用动态信息，这些信息编码在星团的潮汐尾中，以前从未用于此目的。为了利用这一独特的信息，我们将应用我们新的有效方法来生成潮汐尾的数值模型。拟议的项目将汇集我们在球状星团潮汐尾方面的理论专长和我们在外晕星团动力学方面的观测专长。我们将把我们最近开发的数值方法和各种各样的新观测数据结合起来。因此，我们期待此次合作产生强大的协同效应。此外，由于银河系内的质量分布与银河系天文学领域的相关性，我们期望我们的结果对天体物理学界产生重大影响。质量分布对于重建银河系的形成历史和理解银河系暗晕的本质至关重要。最终，了解银河系的质量分布甚至可以测试宇宙结构形成的场景。

The Milky Way is the only spiral galaxy in the Universe that we can investigate from a unique perspective: from the inside. The major research field of Galactic astronomy therefore solely focuses on the understanding of our home galaxy by observations and theory. In this research field, the distribution of mass within the Galaxy represents the vital link between observational findings and theoretical models. However, determinations of the Galactic mass distribution are still very uncertain, especially measurements of the mass and shape of the Galactic dark halo, which dominates the mass distribution at large Galactic radii. Our objective is to measure the Galactic mass distribution out to large Galactic radii by utilizing globular clusters and their tidal tails as tracers of the dark halo mass. We specifically aim at using globular clusters in the outer halo of the Galaxy for studying the shape of the Galactic dark halo, as we find them to be ideally suited for this purpose. We will determine the clusters' orbits to unprecedented precision by fitting numerical simulations to observational data of the clusters and their tidal tails. Precise knowledge of the orbit of a globular cluster allows us to directly infer details on the enclosed mass at the Galactic radius of the respective cluster. In this context, we will also make use of dynamical information, which is encoded in the tidal tails of the clusters and which has not been used for this purpose before. To make use of this unique information, we are going to apply our new and efficient method for generating numerical models of tidal tails. The proposed project will bring together our theoretical expertise on the tidal tails of globular clusters and our observational expertise on the dynamics of outer-halo clusters. We will combine our recently developed numerical methods and a broad variety of new observational data. Hence, we expect a strong synergy form this collaboration. Moreover, due to the relevance of the mass distribution within the Galaxy for the field of Galactic astronomy, we expect our results to have a major impact to the astrophysical community. The mass distribution is of utmost importance for reconstructing the formation history of our Galaxy and for understanding the nature of the Galaxy's dark halo. Ultimately, knowing the mass distribution of our Galaxy even allows for testing scenarios of cosmological structure formation.