The Universe's Hydrogen Budget from z=5 to z=0: Constraints from the Lyman Alpha Forest

宇宙的氢预算从z=5到z=0：来自莱曼α森林的约束克罗茨博士正在研究莱曼α森林云的大小、形状、聚类和数量密度估计之间的联系，以便将它们与星系和数值模型的结果进行比较。克罗茨博士使用数值模型来模拟由冷暗物质主导的气体坍缩反应。他在这项工作中同时使用了地面和HST数据。天文学家有关于这两个极端的详细信息。在零红移时（也就是现在），我们可以测量星系的质量，包括气态物质的数量。在非常高的红移时，由大爆炸设定的同位素丰度比例决定了早期存在多少气体。在这两个极端之间存在着一系列复杂的条件，莱曼阿尔法森林的研究解决了这些条件。莱曼α森林是一组密集的光谱吸收线，聚集在类星体光谱中的莱曼α断裂附近。这些线被认为是来自地球和类星体之间的云层。通过绘制这些云的距离，人们可以推断出宇宙的一些大尺度结构以及其他宇宙学参数。* * * *

Arlin Crotts 9802809 The universe's hydrogen budget from z=5 to z=0: constraints from the Lyman alpha forest Dr. Crotts is studying the connection between the Lyman alpha forest cloud sizes, shapes, clustering and number density estimates in order to compare them with those of galaxies and results from numerical models. Dr. Crotts uses numerical models that simulate the reaction of gas to collapse dominated by cold dark matter. He is using both ground based and HST data for this work. Astronomers have detailed information about the two extremes in lookback time. At zero redshift (i.e., the present) we can measure the masses of galaxies, including how much material is gaseous. At very high redshifts the isotopic abundance rations set by the Big Bang determines how much gas existed at early epochs. In between these extremes lies a complex set of conditions that are addressed by the study of the Lyman alpha forest. The Lyman alpha forest is a dense set of spectroscopic absorption lines that cluster near the Lyman alpha break in the spectrum of quasars. These lines have been identified as coming from intervening clouds between the Earth and the quasar. By mapping the distances of these clouds, one may deduce some of the large scale structure of the universe as well as other cosmological parameters. ****