The Milky Way and its neighbours in the era of large surveys

最近银河系和仙女座星系外围的恒星分布图是一个令人震惊的视觉演示，展示了远离中心的星系的巨大复杂性。它们显示了矮小星系，以及恒星流和其他弥散结构，作为同一“星系生态系统”的一部分，其中星系之间的相互作用和较小星系合并成较大星系似乎代表了这些天体生命周期的一部分。新的和即将到来的设施--最直接的是GAIA，以及LSST和TMT--为更好地理解这个生态系统、其中的矮小星系的作用以及它与宇宙学范式的一致性(或其他方面)提供了极大的机会。我研究的一个核心目标是利用盖亚提供的机会，并通过以研究生培训为中心的研究计划为这些即将到来的科学、技术和数据机会做准备。具体地说，我的学生将使用我是PI的大型调查数据集，这些数据集仅限于对最近星系的特定研究，否则国际社会无法解决这些问题。*我的研究项目涉及恒星天体物理学、星系演化和宇宙学。普遍的宇宙学范式很好地描述了宇宙的大尺度结构，这表明宇宙中的质量是“暗的”(即它不发射电磁辐射)。然而，我们通过它对发光物质的引力影响来推断它的存在，预计所有星系都是在暗物质集中的情况下形成的，这种暗物质被称为“晕”。研究人员现在有责任在更小的空间尺度上测试这一范式，而这一理论最初并不是针对这些空间尺度开发的。在这里，有一些有充分根据的、可测试的预测，但从星系形成的复杂物理中解开这些预测在观测上是非常困难的。最近的星系为许多相关的观测提供了最好的机会。例如，星系晕本质上是非常微弱的，因为尽管它们是银河系大部分质量的家园，但我们可以用来追踪背后暗物质的恒星很少。此外，只有对于附近的宇宙，我们才能进入最小的(“矮小”)星系，这些星系对宇宙学范式构成了一些最重大的挑战，而且似乎是现有的最暗物质主导的系统。我领导了几个项目，旨在提供有关矮小星系属性和星系晕属性的基本数据。我的整个研究计划以研究生培训为中心，利用对这些具有国际竞争力的观测数据集和设施的高水平访问来推动这一新兴领域的发展。

Recent maps of the distribution of stars in the outskirts of the Milky Way and Andromeda galaxies are a startling visual demonstration of the immense complexity of galaxies at large distances from the centre. They show dwarf galaxies, as well as stellar streams and other diffuse structures, as part of the same ``galactic ecosystem'', whereby interactions between galaxies and the merging of smaller galaxies into larger galaxies appear to represent part of the life-cycle of these objects. New and upcoming facilities - most immediately Gaia, as well as LSST and TMT - provide remarkable opportunities for qualitative progress in better understanding this ecosystem, the role of dwarf galaxies within it, and its consistency (or otherwise) with the cosmological paradigm. A core goal of my research is to exploit opportunites presented by Gaia, and to prepare for these upcoming scientific, technological and data opportunities through a research program centered around graduate student training. Specifically, my students will use large survey datasets for which I am PI, and that are uniquely taylored to specific studies of the nearest galaxies that cannot otherwise be addressed by the international community. ***My research program straddles aspects of stellar astrophysics, galaxy evolution, and cosmology. It is well established that the large scale structure of the Universe is well described by the prevailing cosmological paradigm, and it indicates that mass in the Universe is "dark" (i.e., it does not emit electromagnetic radiation). We infer its presence, however, by its gravitational influence on luminous matter, and all galaxies are expected to form within dark matter concentrations called "halos". The onus is now on researchers to test this paradigm on smaller spatial scales for which the theory was not originally developed. Here, there are well-founded, testable, predictions, but unravelling these from the complex physics of galaxy formation is observationally very difficult. The nearest galaxies offer the best opportunities for many of the relevant observations. For example, galaxy halos are intrinsically very faint, since despite being home to most of the mass of the galaxy they have very few stars with which we can hope to trace the underlying dark matter. Further, it is only for the nearby Universe that we can access the smallest ("dwarf") galaxies that provide some of the most significant challenges for the cosmological paradigm, and which appear to be the most dark-matter dominated systems that exist. I lead several programs that are aimed at providing essential data on the properties of dwarf galaxies and on the properties of galaxy halos. My overall research program is centred around graduate student training and utilizes high level access to these internationally competitive observational datasets and facilities to advance this burgeouning field.