Properties of galaxies: constraints from gravitational lensing and dynamics

数学科学：星系的性质：引力透镜和动力学的约束摘要DMS-0104751 Hunter该项目将沿着两条互补的两条线研究星系的大尺度结构。第一行与引力透镜有关，当一个星系靠近我们和一个远得多的源（如类星体）之间的视线时，就会发生引力透镜。来自遥远源的电磁波在接近银河系时都是弯曲和减速的。因此，“引力透镜”可能会产生该类星体的多个图像。许多被星系多次成像的类星体现在是已知的。这些图像的结构和它们的相对大小是由中间星系的质量分布决定的。首席研究员开发了计算椭圆透镜透镜特性的方法。应用于观测数据，这些性质可以用来推断透镜星系的质量分布。他将开发更强大的方法，并在对观测数据进行测试后，根据需要对其进行改进。第二项研究涉及恒星的动力学，它们是星系的主要可见组成部分。它的最终目标是建立星系的动力学模型，但首先要研究两个初步课题。一个是研究中心密度尖峰和中心黑洞，它们被广泛认为存在于许多星系中，如何影响恒星的轨道，以及它们在多大程度上允许星系是三轴的。另一个是改进分析轨道和计算它们的基本频率和轨道密度的程序。这两条研究路线是互补的，因为星系中恒星的轨道和该星系的引力透镜特性都受到星系中所有物质的影响，无论是可见的还是黑暗的。这个项目从两个角度来研究星系——宇宙的基本组成部分。一个是引力透镜效应，另一个是星系中恒星的运动。当光线靠近像星系这样的大质量物体时，会发生弯曲。因此，一个恰好位于我们和遥远的类星体之间的星系可以让我们看到这个物体的多个图像。这种现象被称为引力透镜。它之所以引起当前的极大兴趣，是因为它为研究星系中可见物质和暗物质含量的综合效应提供了一种工具，因为两者都有助于透镜效应。有许多星系的例子产生了同一个遥远类星体的四幅图像。首席研究员正在发展理论，以推断这些图像系统，它们的结构和相对强度，告诉我们这些星系中质量的排列。这种排列对星系的结构至关重要。星系包含着数千亿颗恒星。这些恒星的运动是由引力控制的，这是由于星系的所有质量，包括可见的和黑暗的。了解星系中恒星的运动将有助于了解宇宙的大尺度结构。

NSF Award Abstract - DMS-0104751 Mathematical Sciences: Properties of galaxies: constraints from gravitational lensing and dynamics Abstract DMS-0104751 Hunter The project will follow two complementary two lines of investigation of the large-scale structure of galaxies. The first line is concerned with the gravitational lensing that occurs when a galaxy lies close to the line of sight between us and a much more distant source, such as a quasar. Electromagnetic waves from the distant source are both bent and slowed down as they pass close to the galaxy. As a result, the "gravitational lens" may produce multiple images of that quasar. A number of quasars that are multiply imaged by galaxies are now known. The configuration of those images and their relative magnitudes is determined by the distribution of mass in the intervening galaxy. The principal investigator has developed methods for calculating the lensing properties of elliptical lenses. Applied to observational data, these properties can be used to make deductions about the distribution of mass in the lensing galaxy. He will develop methods that are more powerful and refine them as necessary after testing them on observational data. The second line of investigation is concerned with the dynamics of the stars, which are the major visible components of galaxies. Its ultimate aim is to build dynamical models of galaxies, but two preliminary topics are to be studied first. One is investigation of how central density cusps and central black holes, which are widely believed to be present in many galaxies, influence the orbits of the stars, and to what extent they allow galaxies to be triaxial. The other is to improvement of a procedure for analyzing orbits and computing their fundamental frequencies and orbital densities. The two lines of investigation are complementary because both the orbits of the stars in a galaxy, and the gravitational lensing properties of that galaxy, are influenced by all the matter of the galaxy, whether visible or dark. This project looks at galaxies, the fundamental building blocks of the Universe, from two perspectives. One is that of gravitational lensing and the other is that of the motions of the stars of the galaxies. Light rays are bent when they pass close to a massive object such as a galaxy. Consequently, a galaxy that happens to lie between us and a distant quasar can cause us to see multiple images of that object. This phenomenon is known as gravitational lensing. It is of much current interest because it provides a tool for investigating the combined effects of the visible and dark matter content of a galaxy, since both contribute to the lensing. There are a number of instances of galaxies that produce four images of the same distant quasar. The principal investigator is developing theories for deducing what those image systems, their configurations and their relative strengths, tell us about the arrangement of mass in those galaxies. That arrangement is critical for the structure of the galaxy. Galaxies contain swarms of hundreds of billions of stars. The motions of those stars are governed by the gravitational forces due to all the mass of the galaxy, both visible and dark. Understanding the motion of stars in galaxies will facilitate understanding the large-scale structure of the universe.