Towards a Cosmological View of Disk Galaxy Structure

广泛接受的宇宙构成和演化宇宙学模型解释了一系列引人注目的天文观测。然而，目前尚不清楚星系是如何在这个框架内形成和演化的，而理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创建其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，因为它们的属性可以从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。 **早期测量的螺旋星系结构与简单的理论预测之间的比较发现两者存在很大差异。天文学家现在怀疑，这种分歧并非源于宇宙学的失败，而是源于忽视了星系形成的细节。现在很清楚，气体和恒星在星系形成过程中可以比以前想象的更有效地改变暗物质晕，并且不同星系成分之间的微妙相互作用也可以驱动星系演化。**虽然已经引用了几种看似合理的机制来解释观察到的附近星系的结构，但尚不清楚其中哪些在星系形成过程中是通用的。详细的宇宙学模拟和少数观测到的星系之间的概念验证比较已经取得成功，但仍然缺乏针对人群的星系研究。部分原因是缺乏进行仔细比较所需的附近星系的高质量轨道速度图。随着不同波长的大型光谱调查的出现，这种情况将在不久的将来发生变化。与此同时，现代望远镜的尺寸和效率使得能够对单个星系进行极其详细的研究。 因此，未来几年对于星系形成研究来说是令人兴奋的，因为将有可能首次系统地测试所提出的理论。 **我研究的主要目标是了解宇宙学背景下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。我们代码的物理性和稳健性是无与伦比的，因此我们的团队准备在即将进行的调查中限制附近数千个螺旋星系的暗物质和发光物质含量。我的团队还针对当地宇宙中的极端或独特系统设计并进行了新颖的实验，以便深入了解整个星系群体的物理原理。我的项目提供了一个协作性的、世界一流的培训环境，让高素质人员在其中脱颖而出。**加拿大是天文学领域的国际领先者，经常在该领域排名第一：这种成功催生了技术和创新，使我们的国家在世界舞台上具有竞争优势。我的程序解决了推动天文学研究的一些关键问题：当暗物质晕在其中形成螺旋星系时，暗物质晕如何改变？螺旋星系中恒星和气体的轨道如何驱动它们的演化？当考虑到这些过程时，观测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，朝着我的领域的最终目标——发展宇宙学星系形成和演化的完整理论——取得进展。

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.