Dwarf Galaxies, Abundance Distributions and the Physics of Galaxy Formation

约翰斯顿博士和她的合作研究人员将进行一系列全面的模拟，以跟踪矮星系的化学和动力学演化，矮星系是我们本地宇宙中最常见的星系类型。模拟将包括广泛的相关物理学，包括比氦更重的化学元素的积累，这些元素是由恒星的核反应产生的，并在恒星结束生命时释放到星际气体中。 该团队将首先确定矮星系在大规模宇宙学模拟中形成的位置，然后使用流体动力学代码ENZO以更高的分辨率重新运行该模拟补丁。该代码主要由合作研究者布莱恩开发，提供了比竞争方法更高保真的星际气体动力学和混合处理。该小组将包括一个新的和计算效率高的方法来计算原子序数高达Z=30的元素引起的气体冷却。 在最高分辨率下，ENZO代码将跟踪3-4光年范围内的气体动力学，并且可以包含足够多的恒星粒子来跟踪所有质量至少为太阳一半的单个恒星。 矮星系通常被发现靠近更明亮的星系，这可能会影响它们的形成和演化;该团队将使用他们的模拟来检查这些过程。约翰斯顿博士和她的合作研究人员将从这个项目中产生可视化，在美国自然历史博物馆向公众展示，麦克·洛博士是那里的终身馆长。 约翰斯顿博士还担任哥伦比亚副教务长科学和工程多样性工作组主席，并积极与女学生进行外联。

Dr. Johnston and her co-investigators will perform a comprehensive set of simulations to follow the chemical and dynamical evolution of dwarf galaxies, the most common type of galaxy in our local Universe. The simulations will include a broad range of relevant physics including the buildup of chemical elements heavier than helium, which are produced by nuclear reactions in stars and released to the interstellar gas as the stars end their lives. The team will first identify where a dwarf galaxy forms within a large-scale cosmological simulation, and then re-run that patch of the simulation at much higher resolution with the hydrodynamic code ENZO. This code, largely developed by co-investigator Bryan, provides a higher-fidelity treatment of interstellar gas dynamics and mixing than competing methods. The group will include a new and computationally efficient method to calculate the gas cooling caused by elements with atomic numbers up to Z=30. At its highest resolution, the ENZO code will follow gas dynamics on a scale of 3-4 light years, and can include enough stellar particles to follow all individual stars with at least half the Sun's mass. Dwarf galaxies are normally found close to more luminous galaxies, which can affect their formation and evolution; the team will use their simulations to examine these processes.A graduate student and a postdoctoral fellow will be trained by their involvement in the research. Dr. Johnston and her co-investigators will produce visualizations from this project, to be shown to the public at the American Museum of Natural History, where Dr. Mac Low is a tenured curator. Dr. Johnston also chairs the Vice Provost's Taskforce for Diversity in Science and Engineering at Columbia, and is active in outreach to schoolgirls.