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套全面的模拟，以跟踪矮小星系的化学和动力学演化。矮小星系是我们所在宇宙中最常见的星系类型。模拟将包括广泛的相关物理，包括比氦更重的化学元素的积累，这些元素是由恒星中的核反应产生的，并在恒星结束生命时释放到星际气体中。该团队将首先在大规模宇宙学模拟中确定矮小星系的形成位置，然后使用流体动力学代码Enzo以更高的分辨率重新运行模拟的补丁。该代码主要由合作研究员布莱恩开发，提供了比竞争方法更高保真度的星际气体动力学和混合处理。该小组将包括一种新的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。在其最高分辨率下，恩佐编码将在3-4光年的尺度上跟踪气体动力学，并可以包括足够的恒星粒子来跟踪所有质量至少为太阳一半的单独恒星。矮小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。一名研究生和一名博士后研究员将通过参与这项研究进行培训。约翰斯顿博士和她的合作研究人员将制作这个项目的可视化图像，在美国自然历史博物馆向公众展示，麦克·刘特佐博士是该博物馆的终身馆长。约翰斯顿博士也是哥伦比亚大学副教务长科学与工程多样性特别工作组的主席，并积极接触女学生。

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.