Towards an understanding of galaxy structure

现在人们相信，只有4%的宇宙以普通可见（重子）的形式存在，另外23%的宇宙以非辐射暗物质的形式存在。其余的以暗能量的形式渗透到宇宙中。虽然后者是一个相对较新的推测性概念，但暗物质的引力存在已经为人所知几十年了。暗物质是任何星系形成和演化模型的组成部分；尽管如此，我们还没有准确地绘制出任何星系中可见物质和暗物质的分布。这一提议涉及到可见光和暗物质的测量，以及它们之间的相互作用，以及星系中恒星种群的分布。我们正在进行一项雄心勃勃的计划，利用我们收集的室女座星系团的多波段成像和光谱数据，测量宇宙星系的质量函数，以及星系的尺度关系和恒星群。室女座星系团在现代天体物理学中的重要性怎么估计都不为过，因为它是本地宇宙中主要的质量集中地和最大的星系群。如果我们想要了解星系的本质，包括它们的结构特性、质量/光度分布和暗物质含量，那么显而易见的途径就是对这个试验台星系团及其组成星系进行高灵敏度、多波长的研究。附近仙女座星系的高分辨率光学和红外图像以及银河系球状星团的综合光谱也将用于校准恒星群模型。实现这一提议目标的大部分数据要么已经到位，要么通过批准的遗留调查（如加拿大、法国、夏威夷望远镜下一代室女座星团调查）得到保证。我们还使用数值模拟来模拟星系密度分布并改进星系质量估计器。在接下来的五年里，我计划用这笔资金指导至少5名本科生，7名硕士研究生和2名博士研究生。我小组的研究生培养了观测、计算和理论天体物理学方面的技能，以及研究和教学方法和公共宣传方面的技能。

It is now believed that only 4% of the Universe exists in ordinary visible (baryonic) form, with another 23% in the form of non-radiating dark matter. The remainder permeates the Universe in the form of a dark energy. While the latter is a relatively new, speculative, concept, the gravitational presence of dark matter has been known for many decades. Dark matter is an integral part of any model of galaxy formation and evolution; still, we have yet to accurately map the distribution of visible and dark matter in any galaxy. This proposal is concerned with the measurement of visible and dark matter, and their interplay, as well as the distribution of stellar populations in galaxies. We are pursuing an ambitious program to measure the universal galaxy mass function as well as the scaling relations and stellar populations of galaxies using our multi-band imaging and spectroscopic data collected for Virgo cluster galaxies. The importance of the Virgo cluster in modern astrophysics can scarcely be overestimated as it is the dominant mass concentration and the largest collection of galaxies in the local Universe. If we are to understand the nature of galaxies, including their structural properties, mass/luminosity distribution, and dark matter content, the obvious route forward is through a high-sensitivity, multi-wavelength study of this testbed cluster and its constituent galaxies. Well-resolved optical and infrared images of the nearby Andromeda galaxy and integrated spectra of Milky Way globular clusters will also be used to calibrate stellar population models. Most of the data to achieve the goals of this proposal are either in place or guaranteed through approved legacy surveys (such as the Canada France Hawaii Telescope Next Generation Virgo Cluster Survey). We also use numerical simulations to model galaxy density profiles and refine galaxy mass estimators. Over the next five years, I plan to use this grant to supervise a minimum of five undergraduate students, seven master students, and two doctoral students. The graduate students in my group develop skills in observational, computational and theoretical astrophysics, as well as in research and teaching methods and public outreach.