CAREER: Tracing Gaseous Galaxy Evolution and Galaxies as a Teaching Tool for Middle School and College Students

宇宙的气体探测器可以在低红移的情况下进行详细的探测，并提供对星系如何形成和随时间演化的洞察。玛丽·普特曼博士(密歇根大学)将通过研究星系晕中的气体动力学和电离以及附近矮小星系中的气体浓缩来解决星系形成和演化的关键未知问题。炽热的漫射晕可能仍然含有大量的银河系重子，并为星系盘提供燃料。这种晕介质可以通过银晕中的高速云(HVC)来探测，这些云显示出“头-尾”的结构，或者说是一个高柱状密度的头部，后面是一个扩散的尾巴。对这些云穿过光晕的模拟将与观测结果进行比较，并通过将这些比较与HVC距离限制相结合，将探索弥漫的银河光晕难以捉摸的密度分布、大小和质量。随后将对漫射光晕的来源和作用进行评估。从螺旋星系盘中逸出的电离辐射量将通过对银晕云的H-Alpha观测来研究。银河晕中的辐射将用一定距离范围内的HVC的H-Alpha图进行研究。这将包括麦哲伦流，这是一种气态晕特征，在H-α发射中非常明亮。我们将利用矮小星系外部气体盘中H-II区的金属丰度测量来探测星系积木内的气体流动(远远超出现有的恒星成分)。这将探讨矮星如何演化，以及这些星系中恒星产生的金属去了哪里。作为这项工作的一部分，普特曼博士将通过密歇根大学本科生和研究生的演讲，将这项关于星系演化的研究扩展到底特律地区的中学。这一计划的影响是双重的。首先，不同学区的中学生将体验一项引人入胜的互动计划，旨在激发或保持他们在发展的关键阶段对科学的兴趣。其次，大学生和未来的科学教育者将通过接受演讲培训来收获服务性学习的好处。

Gaseous probes of the universe can be explored in detail at low redshift and provide insight into how galaxies form and evolve throughout time. Dr. Mary Putman (University of Michigan) will address key unknowns of galaxy formation and evolution by examining gas dynamics and ionization in the Galactic halo and gas enrichment in nearby dwarf galaxies. The hot diffuse halo may still harbor a substantial amount of a galaxy's baryons and fuel galaxy disks. This halo medium can be probed with high-velocity clouds (HVCs) in the Galactic halo that show a "head-tail" structure, or a high column density head trailed by a diffuse tail. Simulations of these clouds moving through the halo will be compared to the observations, and by combining these comparisons with HVC distance constraints, the elusive density distribution, size, and mass of the diffuse Galactic halo will be probed. The origin and role of the diffuse halo will subsequently be assessed. The amount of ionizing radiation escaping from spiral galaxy disks will be investigated with H-alpha observations of Galactic halo clouds. The radiation in the Galactic halo will be investigated with H-alpha maps of HVCs at a range of distances. This will include the Magellanic Stream, a gaseous halo feature that is intriguingly bright in H-alpha emission. Gaseous flows within the building blocks of galaxies will be probed with metallicity measurements of H-II regions found in the outer gaseous disks of dwarf galaxies (well beyond an existing stellar component). This will address how dwarfs evolve and where the metals produced by the stars in these galaxies have gone.As a part of this work, Dr. Putman will extend this research on galaxy evolution to middle schools throughout the Detroit-area through presentations done by University of Michigan undergraduate and graduate students. The impact of this program is two-fold. First, middle-school students in diverse school districts will experience an engaging, interactive program designed to trigger or maintain their interest in the sciences at a key stage of their development. Second, college students, and the future science educators, will reap the benefits of service learning by being trained to do the presentations.