RUI/AAG - Studying Metals in Quasars From the Sloan Digital sky Survey: Observing Changes in Galaxy Properties Over Time via Absorption Spectra

第一部分提出的研究旨在将气体云和气体结构与星系及其随时间的变化联系起来。对这些气体云中比氦重的元素的观测为这些元素在太空中产生和传播的总量以及气体云本身的物理环境提供了重要的限制。该提案旨在研究一项重要的天空调查中的大量类星体样本，利用类星体像闪光灯一样观察我们和更遥远的类星体之间的气体云（及其性质）。宇宙的大尺度气体结构受到星系过程中化学元素的产生和扩散的影响。类星体吸收线（QAL）光谱是探测大尺度气体结构及其随时间变化的有力工具。一个逐渐形成的共识是，强吸收线系统可以追踪星系中延伸的气体晕。证据依赖于对星系附近强吸收体的直接探测，以及对吸收体特性随星系变化的直接探测。这种丰富的环星系介质（CGM）的大尺度使得研究星系的形成和变化具有相对较小的观测费用，在大范围的红移。天文学中悬而未决的问题激发了这项研究：星系中延伸的气体晕的化学性质是什么？哪种类型的吸收线系统与哪种类型的星系有关？丢失的金属在哪里？潜在的冷流流向哪些星系？

Part 1The proposed research aims to connect gas clouds and gaseous structures with galaxies and their change over time. The observations of elements heavier than helium in these gas clouds provides important constraints on the overall amount of these elements produced and spread through space, and the physical environments of gas clouds themselves. The proposal seeks to study a large sample of quasars from an important sky survey, using the quasars like a flash light to observe gas clouds (and their properties) between us and the more distant quasars.Part 2The large-scale gaseous structure of the Universe is affected by the production and dispersal of chemical elements by galactic processes. Quasar absorption-line (QAL) spectroscopy is a powerful tool for probing the large-scale gaseous structure and its change over time. There is an emerging consensus that strong absorption-line systems trace the extended gaseous halos of galaxies. The evidence relies on direct detections of strong absorbers near galaxies as well as absorber properties changing with galaxies. The large scale of this enriched circum-galactic medium (CGM) enables the study of galaxy formation and change with relatively little observational expense, at a wide range of redshifts. Open questions in astronomy motivate the research: What are the chemical properties of the extended gaseous halos of galaxies? Which type of absorption-line systems are associated with what class of galaxies? Where are the missing metals? Toward what galaxies are potential cold flows flowing?