测量邻近星系团的横向运动
Measuring Transverse Motions for Nearby Galaxy Clusters
摘要：
测量宇宙中银河系外天体的完整三维运动是一个似乎无法克服的挑战。在本文中，我们调查的应用程序的技术来测量切向运动，以前只适用于附近的本地集团的星系，星系团远远超出其边界。我们表明，映射整个星系团的平均视线运动的原则上可以用来检测“透视旋转”引起的集群的切线运动到视线的投影。对于具有最大角范围、最对称的固有速度分布和以尽可能多的点测量的群集，信号将是最突出的。我们调查的可行性检测这个信号使用三种不同的方法：测量个别集群成员的视线运动;采取光谱的集群内气体;和映射扭曲的宇宙微波背景辐射。我们的结论是，未来的光谱调查的1000的成员附近的星系团持有最有希望的测量集群切向运动使用这种技术。
英文摘要：
Measuring the full three-dimensional motions of extra-galactic objects in the Universe presents a seemingly insurmountable challenge. In this paper we investigate the application of a technique to measure tangential motion that has previously only been applied nearby within the Local Group of galaxies, to clusters of galaxies far beyond its borders. We show that mapping the mean line-of-sight motion throughout a galaxy cluster could in principle be used to detect the "perspective rotation" induced by the projection of the cluster's tangential motion into the line-of-sight. The signal will be most prominent for clusters of the largest angular extent, most symmetric intrinsic velocity distribution and surveyed with the largest number of pointings possible. We investigate the feasibility of detecting this signal using three different approaches: measuring line-of-sight motions of individual cluster members; taking spectra of intracluster gas; and mapping distortions of the Cosmic Microwave Background radiation. We conclude that future spectroscopic surveys of 1000's of members of nearby galaxy clusters hold the most promise of measuring cluster tangential motions using this technique.
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