The Distribution and Evolution of Dark and Luminous Matter in the Universe

宇宙的大部分都是暗的：暗能量、暗物质和暗重子共同主导着密度平衡，只剩下几个百分点的发光恒星或气体。了解这些暗成分的性质和行为是现代宇宙学研究的一个关键目标，但在观测上也是一个挑战。相比之下，在星系和星系团中以恒星和气体的形式出现的发光部分很容易观察到。但是，导致恒星和星系形成的天体物理过程是复杂的，仍然有许多重要的、悬而未决的问题。 这一提议集中在宇宙的这两个相互关联的部分，重点是两个不同领域的项目：(1)使用引力透镜来探测星系周围前所未有的尺度和红移范围内的暗物质分布；(2)研究大尺度结构和速度场，以确定暗物质、星系，特别是暗重子是如何在大尺度上组织起来的。下面我将总结这两个领域中每一个领域的拟议工作。 弱引力透镜使人们能够(从统计上)探测到暗物质，无论是在宇宙尺度上通过形状相关统计还是在星系周围。到目前为止，研究一直集中在这两个量表中的一个或另一个。我将提出一种新的综合方法，利用现有的CFHTLenS数据来理解所有尺度上的亮物质和暗物质之间的关系，并基于现有星系群和星系团的位置建立暗物质分布的完整3D模型。从某种意义上说，观测到的星系是星系结构的骨架，但微弱的透镜显示出骨骼上有多少肉。 从长远来看，一种非常有效的方法是将弱透镜与大规模多目标光谱分析相结合。目前，每种类型的大规模调查之间几乎没有重叠，但斯隆数字天空调查例外，其透镜数据较差。我将建议使用加拿大-法国-夏威夷望远镜进行一项新的大规模弱透镜成像调查，覆盖拥有最佳光谱数据的地区。这样的调查将开启星系透镜研究的新领域，使我们能够详细了解暗物质在更复杂结构中的分布，如星团和细丝，以及潮汐剥离等物理现象。 奇特速度是指观测到的偏离宇宙均匀膨胀的速度。通过将这些观测与我们的邻近宇宙地图上的预测进行比较，在大尺度上量化星系和暗物质之间的关系，测量宇宙学参数，并测试引力本身。 一个长期存在的挑战是找出“失踪的”重子，它们被认为是星际介质(IM)中的电离氢。由于密度和温度低，很大一部分IM很难直接检测到。理论上，在宇宙微波背景下，IM可以通过对自由电子动量敏感的动力学Sunyaev-Zeldovich效应来探测。我们的团队最近通过将我们的局部密度和速度场地图的预测与威尔金森微波各向异性探测器(WMAP)的温度地图进行比较，对这种效应进行了初步检测。我们将把这一分析扩展到普朗克卫星的温度。WMAP上的额外灵敏度和分辨率应该第一次允许对IM中所有缺失的重子进行重大探测，并可能允许我们确定它们相对于星系的空间分布。 通过结合这些方法的结果，我们将对宇宙光明和黑暗之间的联系有新的洞察力。

Most of the Universe is dark: dark energy, dark matter, and dark baryons collectively dominate the density budget leaving only a few percent in luminous stars or gas. Understanding the nature and behaviour of these dark components is a key goal of modern cosmological studies, but one which is observationally challenging. In contrast, the luminous sector, in the form of stars and gas in galaxies and clusters, is readily observable. But the astrophysical processes that led to the formation of stars and galaxies are complex, and there remain many important, open questions. This proposal is focussed on both of these inter-linked sectors of the Universe, with an emphasis on projects in two different areas: (1) using gravitational lensing to probe the distribution of dark matter around galaxies over an unprecedented range of scales and redshifts; (2) a study of large-scale structure and velocity fields to determine how dark matter, galaxies and, in particular, dark baryons are organized on large scales. Below I will summarize proposed work in each of these two areas. Weak gravitational lensing allows one to (statistically) detect dark matter, either on cosmic scales through shape correlation statistics or around galaxies. Up until now, studies have focussed on one or the other of these two scales. I will propose a new comprehensive approach using existing CFHTLenS data to understand the relationship between light and dark matter on all scales and to build a full 3D model of the dark matter distribution, based on the locations of existing galaxies in groups and clusters. In a sense, the observed galaxies are the skeleton of the structure but weak lensing shows how much meat is on the bones. In the longer term, a very powerful approach is to combine weak lensing with large-scale multi-object spectroscopy. At present there is little overlap between large-scale surveys of each type, with the exception of Sloan Digital Sky Survey for which the lensing data is poor. I will propose a new large-scale weak lensing imaging survey using the Canada-France-Hawaii Telescope that covers the regions with the best spectroscopic data. Such a survey would open up a new regime in galaxy-galaxy lensing allowing a detailed understanding of dark matter distribution in more complex structures such as groups and filaments, as well as physical phenomena such as tidal stripping. Peculiar velocities are the observed deviations from the uniform expansion of the Universe. By comparing these observations with predictions from our map of the nearby Universe, quantify the relationship between galaxies and dark matter on large scales, measure the cosmological parameters, and test gravity itself. A long standing challenge has been to identify the "missing" baryons, presumed to be ionized hydrogen in the intergalactic medium (IM). Much of this IM has been difficult to detect directly because of its low density and temperature. In principle, the IM can be detected via the kinetic Sunyaev-Zeldovich effect in the Cosmic Microwave Background, which is sensitive to the momentum of the free electrons. Our group as recently made a tentative detection of this effect by comparing the predictions of our map of the local density and velocity fields with the Wilkinson Microwave Anisotropy Probe (WMAP) temperature map. We will extending this analysis to Planck satellite temperatures. The additional sensitivity and resolution over WMAP should allow, for the first time, a significant detection of all of the missing baryons in the IM, and may allow us to determine their spatial distribution with respect to galaxies. By combining results from these approaches we will gain new insight into the link between the light and dark sides of the Universe.