U.S.-China Cooperative Research (Astronomy): Quasar Absorption Lines: Physical Conditions in the Early Universe

这是一个为期两年的合作项目， 亚利桑那大学的吉尔·贝克托尔德和 南京大学的黄克良来学习 早期宇宙的物理条件。 的 该项目由NSF和中国国家赞助 教育委员会。 在光谱中观察到的吸收线， 非常遥远的类星体提供了一个强大的探测器， 沿着视线插入气体。 高 类星体的光度使天文学家能够研究 宇宙在很远的距离，因此在时代 当时的宇宙只有 当前年龄 这是一个时期，许多重要的 事件发生了..形成和快速早期 星系的演化， 大型结构的坍塌，例如 星系和超星系团， 类星体本身。 一些类星体吸收 线是由星际中的云造成的 正常星系的介质;其他星系际的介质 正常星际介质中的云 星系;其他星系间的云， 可能代表前银河系或原始银河系 富含原始金属的物质。 在任一 类星体吸收线提供了直接的 关于物理条件的信息， 早期宇宙中的天体太过微弱， 学习任何其他方式。 这个项目的目标是分析 类星体吸收线的详细光谱 可以用现有的望远镜获得， 仪器仪表 光谱由以下获得： 4米望远镜中阶梯光栅光谱 在基特峰国家天文台。

This is a two.year collaborative project between Jill Bechtold of the University of Arizona and Huang Keliang of Nanjing University to study physical conditions in the early universe. The project is sponsored by NSF and the Chinese State Education Commission. The absorption lines observed in the spectra of very distant quasars provide a powerful probe of intervening gas along the line of sight. The high luminosities of quasars enable astronomers to study the Universe at great distances and hence at epochs when the Universe was about 20 percent of its current age. This was a period when many important events took place .. the formation and rapid early evolution of galaxies, the beginnings of the collapse of large structures such as clusters of galaxies and superclusters, and the rapid turn.on of quasars themselves. Some quasar absorption lines are caused by clouds in the interstellar medium of normal galaxies; others by intergalactic clouds in the interstellar medium of normal galaxies; others by intergalactic clouds that probably represent pre.galactic or proto.galactic material of primordial metal abundance. In either case, quasar absorption lines provide direct information about the physical conditions in objects in the early Universe that are too faint to study any other way. This goal of this project is to analyze the most detailed optical spectra of quasar absorption lines obtainable with currently available telescopes and instrumentation. The spectra were obtained with the echelle spectro>g.raph at the 4 meter telescope at the Kitt Peak National Observatory.