Towards a Cosmological View of Disk Galaxy Structure

这个被广泛接受的关于宇宙组成和演化的宇宙学模型解释了一系列显著的天文观测结果。然而，目前还不清楚星系是如何在这个框架内形成和演化的，而了解这个过程是如何发生的是当今宇宙学中最大的挑战之一。对我们周围星系的详细观察为我们了解形成星系内部结构的过程提供了重要线索。类似于银河系的螺旋星系在这方面特别有用，因为它们的性质可以从其圆盘中气体和恒星的分布和轨道速度推断出来。因此，对附近螺旋星系的详细结构研究提供了关键证据，使天文学家能够破译星系形成和演化的物理原理。**螺旋星系的测量结构与简单的理论预测之间的早期比较发现两者之间存在很大的差异。天文学家现在怀疑，这种分歧不是来自宇宙学的失败，而是来自被忽视的星系形成的细节。现在很清楚，在星系形成过程中，气体和恒星可以比以前认为的更有效地改变暗物质晕，而不同星系组成部分在形成后的微妙相互作用也可以推动星系的演化。**虽然有几种看似合理的机制被用来解释观测到的附近星系的结构，但尚不清楚哪一种机制在星系形成过程中是通用的。详细的宇宙学模拟和少量观测到的星系之间的概念验证比较已经取得了成功，但大规模的星系研究仍然缺乏。这在一定程度上是由于缺乏高质量的附近星系轨道速度图，而这些轨道速度图是进行仔细比较所必需的。在不久的将来，随着不同波长的大型光谱调查的出现，这种情况将会改变。与此同时，现代望远镜的大小和效率使得对单个星系的细致研究成为可能。因此，对于星系形成研究来说，未来几年将是令人兴奋的几年，因为将有可能首次系统地检验提出的理论。**我研究的主要目的是在宇宙学背景下了解附近螺旋星系的结构。我的研究小组使用我们为此目的开发的软件对大型星系样本进行系统的结构研究。我们的代码的物理性质和健壮性是无与伦比的，因此我们的团队准备在即将到来的调查中限制附近数千个螺旋星系的暗物质和发光物质的含量。我的小组还设计并实施了一些关于局部宇宙中极端或独特系统的新颖实验，以深入了解整个星系人口的物理特性。我的项目提供了一个协作的、世界级的培训环境，高素质的人才在其中脱颖而出。**加拿大在天文学方面处于国际领先地位，经常在该领域排名第一：这一成功带来了技术和创新，使我们的国家在世界舞台上具有竞争优势。我的项目解决了一些推动天文学研究的关键问题：当螺旋星系在其中形成时，暗物质晕是如何改变的？螺旋星系中恒星和气体的轨道是如何推动它们的演化的？当考虑到这些过程时，观察到的螺旋星系结构是否与宇宙学预测一致？暗物质的本质是什么？我的工作将有助于回答这些问题，使我的领域的最终目标取得进展，即建立一个完整的宇宙星系形成和演化理论。

The broadly-accepted cosmological model for the composition and evolution of the Universe explains a remarkable range of astronomical observations. However, it is not yet clear how galaxies form and evolve within this framework, and understanding how this process happens is one of the biggest challenges in cosmology today. Detailed observations of the galaxies around our own provide important clues to the processes that create their internal structure. Spiral galaxies similar to the Milky Way are particularly useful in this regard, because their properties can be inferred from the distributions and orbital speeds of gas and stars in their disks. Detailed structural studies of nearby spiral galaxies therefore provide key evidence that allows astronomers to decipher the physics of galaxy formation and evolution. **Early comparisons between the measured structure of spiral galaxies and simple theoretical predictions found that the two were strongly discrepant. Astronomers now suspect that this disagreement arises not from a failure of cosmology, but from overlooked details of how galaxies form. It is now clear that gas and stars can alter dark matter halos during galaxy formation more efficiently than previously thought, and that the subtle interplay between different galactic components after they have formed can also drive galaxy evolution.**While several plausible mechanisms have been invoked to explain the observed structure of nearby galaxies, it is not yet clear which of them are generic during galaxy formation. Proof-of-concept comparisons between detailed cosmological simulations and handfuls of observed galaxies have been successful, but population-wide galaxy studies are still lacking. This is due in part to a dearth of high-quality orbital speed maps for nearby galaxies required for these careful comparisons. This will change in the near future with the advent of large spectroscopic surveys at different wavelengths. At the same time, the size and efficiency of modern telescopes enable exquisitely detailed studies of individual galaxies. The next few years are therefore exciting ones for galaxy formation research, since it will be possible to systematically test proposed theories for the first time. **The main objective of my research is to understand the structure of nearby spiral galaxies in a cosmological context. My research group carries out systematic structural studies of large galaxy samples using software that we have developed for this purpose. The physicality and robustness of our code are unparallelled, and our group is therefore poised to constrain the dark and luminous matter contents of thousands of nearby spiral galaxies from forthcoming surveys. My group also devises and carries out novel experiments on extreme or unique systems in the local Universe, in order to gain insight into the physics of the galaxy population as a whole. My program provides a collaborative, world-class training environment in which highly qualified personnel excel.**Canada is an international leader in astronomy, often ranking first in this field: this success engenders technology and innovation that give our country a competitive edge on the world stage. My program addresses some of the key questions that drive astronomical research: how are dark matter halos altered when spiral galaxies form within them? How do the orbits of the stars and gas in spiral galaxies drive their evolution? Is the observed structure of spiral galaxies consistent with cosmological predictions when these processes are taken into account? What is the nature of the dark matter? My work will help answer these questions, making progress towards my field's ultimate goal of developing a complete theory of cosmological galaxy formation and evolution.