QSO Absorption Lines and Cosmology

类星体光谱中观察到的华莱士星吸收线为研究星系中的星际气体和沿视线到类星体的星际介质中的气体提供了一种方法。萨金特博士正在扩展一个类星体吸收线研究项目中的观察和分析。他正在凯克10米望远镜上使用高分辨率回声光谱仪(HIRES)。它有三个目标：(1)研究星系和星际介质中重元素含量随宇宙时间的变化而从红移约5(当时宇宙约为其年龄的10%)向前推进到本时代；(2)利用在引力透镜类星体或类星体对的多幅图像中观测到的吸收线，研究星系和星际空间中气体的结构，范围从10pc到100kpc，以及(3)研究能够电离氢的紫外线辐射的准银河系通量的宇宙演化。这项研究讨论了类星体和星系在不同宇宙时期对电离通量的贡献的相对重要性。

QSO absorption lines and comsologyWallace SargentAbsorption lines observed in the spectra of quasars provide a way to study the interstellar gas in galaxies and gas in the intergalactic medium along the line of sight to the quasar. Dr. Sargent is extending observations and analyses in a program of quasar absorption line studies. He is using the High Resolution Echelle Spectrograph (HIRES) on the Keck 10 meter telescopes. There are three objectives: (1) to study the evolution of the heavy element content of galaxies and the intergalactic medium as a function of cosmic time from redshift about 5 (when the universe was about 10% of its present age) forward to the present epoch; (2) to study the structure of the gas in galaxies and intergalactic space on scales ranging from 10pc to 100kpc using the absorption lines observed in multiple images of gravitationally lensed quasars or quasar pairs, and (3) to study the cosmical evolution of the meta-galactic flux of UV radiation capable of ionizing hydrogen. This investigation addresses the relative importance of the contributions of quasars and galaxies to the ionizing flux at different cosmic epochs.