Investigations of a Statistically Complete Sample of Galaxy Clusters

最近完成的由ROSAT卫星进行的x射线全天巡天可以提供星系团的样本，这些星系团既具有完善的可量化选择标准，又位于天空的连续区域。为了获得这个样本，有必要从更多的其他来源中识别群集。首席研究员只是受邀参加ROSAT调查的少数几位美国天文学家之一，并且可以在发布之前很好地访问这些x射线数据。这笔拨款将为星团样本的后续光学研究提供支持，特别强调星团的初步鉴定，以及后来对x射线和光学性质的演变、大尺度结构和经典星等红移关系的研究。对卫星数据的分析将使我们能够对以前的研究作出重大改进。

The recently completed X-ray all-sky survey carried out by the ROSAT satellite can provide a sample of clusters of galaxies which has both well established quantifiable selection criteria and is in a contiguous region of the sky. To obtain this sample it is necessary to identify the clusters from the more numerous other sources. The Principal Investigator is only one of a few US astronomers who were invited to participate in the ROSAT survey and has access to this X-ray data well in advance of publication. This grant will provide support for follow-up optical studies of the cluster sample with particular emphasis on the initial identification of the clusters and later investigations of evolution of X-ray and optical properties, large scale structure, and the classical magnitude-redshift relation. Analysis of the ROSAT data will enable significant improvements over previous studies to be made.