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

宇宙中暗物质和发光物质的分布和演化

• 批准号: RGPIN-2014-06481
• 负责人: Hudson, Michael
• 金额: $ 3.06万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=589036
• 关键词: Distribution; Evolution; Dark; Luminous; Matter

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.

宇宙的大部分是暗的：暗能量、暗物质和暗重子共同主导了密度预算，只留下几个百分比的发光恒星或气体。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，但在观测上具有挑战性。相比之下，在星系和星系团中以恒星和气体形式存在的发光区很容易观察到。但是，导致恒星和星系形成的天体物理过程是复杂的，仍然存在许多重要的悬而未决的问题。 这项建议的重点是宇宙中这两个相互关联的部分，重点是两个不同领域的项目：（1）利用引力透镜探测星系周围暗物质在前所未有的尺度和红移范围内的分布;（2）研究大尺度结构和速度场，以确定暗物质，星系，特别是，暗重子在大尺度上是有组织的。下面我将总结这两个领域的拟议工作。 弱引力透镜允许人们（在统计上）探测暗物质，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，研究集中在这两个尺度中的一个或另一个。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光和暗物质之间的关系，并根据现有星系群和星系团的位置，建立一个完整的暗物质分布3D模型。从某种意义上说，观测到的星系是结构的骨架，但弱透镜显示了骨头上有多少肉。 从长远来看，一个非常强大的方法是将联合收割机弱透镜与大规模多目标光谱学结合起来。目前，每种类型的大规模巡天之间几乎没有重叠，但斯隆数字巡天除外，因为它的透镜数据很差。 我将提出一个新的大规模弱透镜成像调查使用加拿大-法国-夏威夷望远镜，涵盖了最好的光谱数据的地区。这样的调查将开辟一个新的制度，在星系星系透镜允许详细了解暗物质分布在更复杂的结构，如集团和细丝，以及物理现象，如潮汐剥离。 奇异速度是观测到的宇宙均匀膨胀的偏差。通过将这些观测结果与我们对附近宇宙的预测进行比较，量化大尺度上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确定“失踪”的重子，假设是星系际介质（IM）中的电离氢。由于密度和温度低，这种IM的大部分难以直接检测。原则上，IM可以通过宇宙微波背景中的动力学Sunyaev-Zeldovich效应来检测，该效应对自由电子的动量敏感。我们的小组最近通过比较我们的局部密度和速度场图与威尔金森微波各向异性探测器（WMAP）温度图的预测，对这种效应进行了试探性的探测。 我们将把这种分析扩展到普朗克卫星的温度。WMAP的额外灵敏度和分辨率应该允许，第一次，在IM中的所有失踪的重子的显着检测，并可能使我们能够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，我们将获得对宇宙光明面和黑暗面之间联系的新见解。