Galaxy groups and clusters: Galaxy evolution and cosmology

过去十年中大型星系调查的结果表明，星系的形成和演化与星系周围的环境密切相关，例如，星系的局部密度。星系团和星系群是宇宙中最大的受引力约束的物体，是研究星系的性质和生命演化如何依赖于环境的绝佳实验室。此外，星系团作为宇宙大尺度结构中密度最高区域的标志，也为我们限制宇宙的宇宙学模型提供了一种方法；特别是，通过计算它们的数量作为宇宙中年龄的函数。我一直在进行两个最大的光学和红外成像调查，以寻找遥远的星系团和星系群，超过三分之二的路程到达可观测宇宙的边缘。调查的数据收集阶段已于过去两年完成。这些调查使我们能够发现宇宙年龄为当前年龄三分之一时的星团，涵盖了很长的时间线。数以万计的星系团和星系群的大样本，以及更详细的光谱后续观测，将使我们能够在这个提议中理解驱动星系环境与其演化之间联系的机制。我们还将在星系团后面发现大量（大约100个）引力透镜（即被放大的）非常遥远的星系，这将使我们能够研究宇宙在15亿年前年轻时星系的形成。

Results from large galaxy surveys in the last decade have shown that the formation and evolution of galaxies are intimately tied to the environment around the galaxies, e.g., the local density of galaxies. Galaxy clusters and groups, the largest gravitationaly bound objects in the universe serve as excellent laboratories in learning how the properties and lifetime evolution of galaxies depend on their environment. Furthermore, galaxy clusters, as marker of the highest density regions of the large scale structure in the universe, also provide a way to allow us to constrain the cosmological model of the universe; in particular, by counting their numbers as a function of age in the universe. I have been conducting two of the largest imaging surveys in optical and IR wavelengths to find distant clusters and groups of galaxies, more than two-third way to the edge of the observable universe. The data gathering phase of the surveys has been completed in the last two years. These surveys allow us to discover clusters at the time when the universe was 1/3 the current age, covering a large time line. The large samples of several tens of thousands of galaxy clusters and groups, and more detailed spectroscopic follow-up observations, will allow us, in this proposal, to understand the mechanisms that drive the connections between the environment of galaxies and their evolution in time. We will also discover a large number (about 100) of gravitationally lensed (i.e., magnified) very distant galaxies behind the clusters, which will allow us to study the formation of galaxies when the universe was as young as one and a half billions years old.