Fundamental Modes of Galaxy Formation Through Cosmic Time

星系被认为主要是通过较小星系的合并和来自星际介质(IGM)的冷气体的吸积而形成的。该项目的目的是直接探测像银河系这样的当今星系的低质量积木，以及从IGM到气态晕和气盘的气体运输的特征。合作团队将利用光谱观测，与宽带或窄带成像相比，光谱观测可以在微弱星系和天空背景之间提供更高的对比度，并将利用最近仪器灵敏度的提高及其使用大型望远镜的机会。该团队将执行4个不同的子项目：(1)光谱搜索来自IGM和高红移星系的莱曼-阿尔法辐射。其目的是揭示星系形成早期阶段气体的空间范围、运动学和能量学。(2)亮Lyman-α星系的线型分析。这些数据将被用来限制星系流入和流出的相对重要性。(3)背景类恒星(QSO)光谱中镁离子吸收系统的高分辨光谱。这些数据将被用来理解没有当前恒星形成的星系中冷气云的来源。(4)对本地星系进行深入的二维Balmer-Alpha搜索，以努力探测从光晕凝聚到盘面上的冷晕云。这些项目旨在为卡内基研究所博士前奖学金项目的研究生提供博士论文项目。首席研究员还将参与指导克莱蒙特学院的本科生进行天文学研究。

Galaxies are thought to form primarily through the merging of smaller galaxies and the accretion of cold gas from the intergalactic medium (IGM). The aim of this project is to directly detect the low mass building blocks of present-day galaxies like the Milky Way and the signatures of gas transport from the IGM into gaseous halos and disks. The collaborating team will make use of spectroscopic observations that can provide higher contrast between faint galaxies and the sky background than broad- or narrow-band imaging, and will take advantage of recent increases in instrumental sensitivity and their access to large telescopes. The team will carry out 4 distinct sub-projects: (1) Spectroscopic searches for Lyman-alpha emission from the IGM and high redshift galaxies. The aim is to reveal the spatial extent, kinematics and energetics of gas in the early stages of galaxy formation. (2) Line-profile analysis of bright Lyman-alpha galaxies. The data will be used to constrain the relative importance of infall and outflow in galaxies. (3) High resolution spectroscopy of MgII absorption systems in the spectra of background quasi-stellar objects (QSOs). These data will be used to understand the origin of cool gas clouds in galaxies without current star formation. (4) A deep, two-dimensional Balmer-alpha search of local galaxies in an effort to detect cool halo clouds condensing from the halo onto the disk. These projects are intended to be available as doctoral dissertation projects for graduate students in the Carnegie Institution's pre-doctoral fellowship program. The Principal Investigator will also participate in supervising undergraduate students from the Claremont Colleges in astronomy research.