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下详细探索，并提供星系如何形成和演化的洞察力。玛丽普特曼博士（密歇根大学）将通过研究银河系晕中的气体动力学和电离以及附近矮星系中的气体富集来解决星系形成和演化的关键未知因素。 热的弥漫晕可能仍然隐藏着相当数量的星系重子和燃料星系盘。这种晕介质可以用银河系晕中的高速云（HVC）来探测，这些云显示出“头-尾”结构，或者是高密度的头部被弥散的尾部所尾随。 这些云在晕中移动的模拟将与观测结果进行比较，并通过将这些比较与HVC距离约束相结合，将探索弥漫的银河系晕的难以捉摸的密度分布，大小和质量。随后将评估扩散晕的起源和作用。 从螺旋星系盘逃逸的电离辐射量将通过对银河晕云的H-α观测来研究。银河晕中的辐射将用HVC在一定距离范围内的H-α图进行研究。这将包括麦哲伦流，一种气态晕特征，在H-α发射中非常明亮。 将通过对矮星系外部气体盘（远远超出现有恒星组成部分）中发现的H-II区域的金属丰度测量来探测星系结构单元内的气体流动。这将解决矮星如何演变，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，将星系演变的研究扩展到整个底特律地区的中学。该计划的影响是双重的。首先，不同学区的中学生将体验一个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工作者将通过接受培训来做演示来获得服务学习的好处。

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.