Properties of galaxies: constraints from gravitational lensing and dynamics

0104751数学科学奖：星系的性质：引力透镜和动力学的制约这个项目将沿着两条互补的星系大尺度结构的研究路线进行。第一条线与引力透镜有关，当星系位于我们和更远的源(如类星体)之间的视线附近时发生的引力透镜。来自遥远来源的电磁波在靠近银河系时会发生弯曲和减速。因此，“引力透镜”可能会产生该类星体的多幅图像。许多被星系倍增成像的类星体现在已为人所知。这些图像的形状和它们的相对星等由中间星系中的质量分布决定。首席研究员提出了计算椭圆形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中的质量分布。他将开发更强大的方法，并在对观测数据进行测试后，根据需要进行改进。第二条线与恒星的动力学有关，恒星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。一个是研究中央密度尖点和中央黑洞，人们普遍认为它们存在于许多星系中，它们如何影响恒星的轨道，以及它们在多大程度上允许星系三轴。另一个是改进轨道分析和计算轨道基频和轨道密度的程序。这两条研究路线是相辅相成的，因为星系中恒星的轨道和该星系的引力透镜性质都受到该星系所有物质的影响，无论是可见的还是黑暗的。这个项目从两个角度考察了星系，这是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运动的效应。光线在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该天体的多幅图像。这种现象被称为引力透镜。它目前很受关注，因为它提供了一种工具来研究星系中可见物质和暗物质含量的综合影响，因为两者都对透镜有贡献。有许多星系产生了同一遥远类星体的四幅图像。首席研究人员正在开发理论，以推断这些成像系统、它们的配置和它们的相对强度，告诉我们那些星系中的质量排列。这种安排对银河系的结构至关重要。星系中有成群的数千亿颗恒星。由于星系的所有质量，无论是可见的还是黑暗的，这些恒星的运动都受到引力的控制。了解星系中恒星的运动将有助于理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.