The Dynamics of Galaxy Evolution

温伯格博士和他的小组将通过星系盘、球状体和暗物质晕之间的集体相互作用来研究星系在数十亿年的时间里是如何演化的。 作用于这些大尺度的主要力量是恒星和暗物质的相互引力。星系被认为是由许多较小的单位合并而成的;在这段时间里，引力变化很大。 在宇宙历史早期看到的银河系通常有非常大的酒吧;该小组将探索这些大酒吧如何在这个早期的暴力阶段产生。然后，他们将研究在银河系更安静的后期生活中，这样大的棒如何收缩成今天看到的更短，旋转更快的棒。 他们还将研究恒星盘如何在宇宙历史中逐渐弯曲和增厚，以及中央隆起如何形成。 在这项研究中，他们将使用微扰理论，恒星轨道的直接积分和N体模拟的几种类型的组合。为了研究圆盘中的气体如何影响星系的发展，他们将联合收割机将他们的N体代码与遵循气体动力学的代码相结合，并将实现多时间步长算法，该算法将使模拟吞吐量增加30倍。 该奖项将资助一名研究生，该小组将为本科生提供研究项目，包括他们机构计算机动画组的学生。 这些学生将接受数字和可视化技术的培训。 该小组将为他们的模拟代码分发测试套件和工具，以及参考解决方案，使该领域的其他研究人员能够比较他们自己的代码在相同测试问题上的详细结果。 他们还将从计算中产生可视化和其他外展材料。

Dr Weinberg and his group will examine how galaxies evolve over billions of years, by the collective interactions between their disk, spheroid, and dark-matter halo. The main force acting on these large scales is the mutual gravitational pull of the stars and the dark matter. Galaxies are believed to form by the merger of many smaller units; during this time, gravitational forces vary wildly. Galaxies seen early in cosmic history often have very large bars; the group will explore how these large bars could be produced in this early violent phase. They will then examine how, in the quieter later life of the galaxy, such large bars could shrink to become the shorter and faster-rotating bars seen today. They will also investigate how the disk of stars could become warped and thickened, and how the central bulge might be built up, slowly over cosmic history. In this investigation they will use a combination of perturbation theory, direct integration of stellar orbits, and N-body simulations of several types. To study how gas in the disk affects the galaxy's development, they will combine their N-body code with a code to follow gas dynamics, and will implement a multiple time step algorithm that should increase the simulation throughput by 30 times. The result will be detailed predictions for the motions of stars and gas in present-day galaxies.This award will support a graduate student, and the group will offer research projects to undergraduates, including those in their institution's computer animation group. These students will be trained in numerical and visualization techniques. The group will distribute test suites and tools for their simulation codes, together with reference solutions, to enable other researchers in the field to compare the detailed results of their own codes on the same test problems. They will also produce visualizations and other outreach material from their computations.