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Diagnostics of Cosmic Discordance

宇宙不和谐的诊断

基本信息

批准号：
ST/G002231/1
负责人：
Peter Coles
金额：
$ 42.38万
依托单位：
CARDIFF UNIVERSITY
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2009
资助国家：
英国
起止时间：
2009 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=ST%2FG002231%2F1
关键词：
Diagnostics Cosmic Discordance

项目摘要

The last twenty years have seen a revolution in the field of Cosmology which has led to the establishment of a standard model that accounts, at least in a broad-brush sense, for most of the observed properties of our Universe; this model is frequently dubbed 'the concordance' model. This progress has been brought about by an exciting synthesis of theoretical ideas about the early stages of the Big Bang with data from large-scale galaxy surveys and observations of the cosmic microwave background. One of the most important challenges for the future development of cosmology is to discover, diagnose and explain departures from the concordance model because these would offer the prospect of learning more about the origins of our Universe. One particularly important element of the concordance cosmology is that quantum fluctuations on sub-atomic scales were stretched many orders of magnitude during a period of inflation, becoming sound waves in the process. This is what put the 'bang' in the 'big bang'. Moreover these sound waves are detectable both in the pattern of temperature variations on the sky seen in the cosmic microwave background and in the clustering properties of the large-scale distribution of galaxies. In the simplest versions of inflation, these fluctuations are random and have the simplest possible statistical form, a Gaussian (or 'normal') distribution. We do not, however, know how, or even if, inflation actually happened or whether it was simple or not; there are apparently viable models, such as those deriving from string theory, that offer radically different descriptions of the early Universe. One of the most exciting ways of probing the fundamental physics involved in the origin of the Universe is to look for evidence of primordial non-Gaussianity in the observed properties of our Universe. We know from the success of the concordance model that any departures from 'normality' must be relatively small, so this approach requires sophisticated statistical techniques of a different nature to those required for measuring the relatively simple characteristics needed to establish the standard model. The size and complexity of the data sets, the possibility of contamination with noise or systematic errors, and the mathematical subtleties involved in characterizing random fluctuation fields all combine to make this approach a challenging one. Even in current data sets, such as those derived from the Wilkinson Microwave Anisotropy Probe (WMAP), there are already indications that there might be things going on that are inconsistent with the standard cosmology. There is an unexplained 'cold spot' on the sky, there are peculiar alignments in the temperature pattern, and there is a large-scale variation across the sky, to name just a few. Are these caused by experimental systematics or do they suggest that the concordance model may be incomplete? In future, satellites such as Planck will yield more information about these suggested anomalies. It is obviously essential to prepare for the flood of new data by developing analysis techniques capable of exploiting it. The research described in this proposal is designed to develop and test sophisticated new ways of analysing astronomical data for signs of primordial discordance. The approach we take highlights the intriguing nature of cosmology, in that it is closer to forensic science or archaeology than it is to laboratory-based disciplines. We have acess to only one Big Bang, so there are no opportunities to re-run the experiment with slightly different initial conditions. We must piece together what happened from fragmentary and noisy data, sifting through the aftermath of the primordial explosion for clues to what caused it. The more detailed the questions we ask, the more complicated is the processing required required to extract relevant information. It is painstakingly precise work, but it is a sign that cosmology has at last become a proper science.

在过去的20年里，宇宙学领域发生了一场革命，导致了一个标准模型的建立，这个模型至少在广义上解释了我们宇宙的大多数观测性质;这个模型经常被称为“和谐”模型。这一进展是通过对大爆炸早期阶段的理论观点与大规模星系调查和宇宙微波背景观测的数据进行令人兴奋的综合而实现的。宇宙学未来发展的最重要挑战之一是发现、诊断和解释与和谐模型的偏离，因为这将提供更多关于我们宇宙起源的前景。协和宇宙学的一个特别重要的元素是，在暴胀期间，亚原子尺度上的量子涨落被拉伸了许多数量级，在这个过程中变成了声波。这就是“大爆炸”中的“爆炸”。此外，这些声波可以在宇宙微波背景中看到的天空温度变化模式和星系大尺度分布的聚类特性中检测到。在暴胀的最简单版本中，这些波动是随机的，并且具有最简单的统计形式，高斯（或“正态”）分布。然而，我们不知道暴胀是如何发生的，甚至不知道暴胀是否真的发生了，也不知道暴胀是否简单。显然有一些可行的模型，比如从弦理论中推导出来的模型，对早期宇宙提供了截然不同的描述。探索宇宙起源所涉及的基本物理学的最令人兴奋的方法之一是在我们宇宙的观测属性中寻找原始非高斯性的证据。我们从和谐模型的成功中知道，任何偏离“正态性”的情况都必须相对较小，因此这种方法需要与测量建立标准模型所需的相对简单特征所需的技术不同的复杂统计技术。数据集的大小和复杂性，噪声或系统误差污染的可能性，以及描述随机波动场所涉及的数学微妙性，所有这些联合收割机都使这种方法具有挑战性。即使在目前的数据集，如那些来自威尔金森微波各向异性探测器（WMAP），已经有迹象表明，可能有一些事情是不符合标准的宇宙学。天空中有一个无法解释的“冷点”，温度模式中有特殊的排列，天空中有大规模的变化，仅举几例。这些是由实验系统学引起的，还是表明一致性模型可能是不完整的？未来，像普朗克这样的卫星将提供更多关于这些异常的信息。显然，必须为大量新数据作好准备，开发能够利用这些数据的分析技术，本提案所述的研究旨在开发和测试分析天文数据以寻找原始不一致迹象的先进新方法。我们采取的方法突出了宇宙学的有趣本质，因为它更接近法医学或考古学，而不是基于实验室的学科。我们只能接触到一次大爆炸，所以没有机会在稍微不同的初始条件下重新运行实验。我们必须从支离破碎的数据中拼凑出发生了什么，从原始爆炸的余波中筛选出导致爆炸的线索，我们问的问题越详细，提取相关信息所需的处理就越复杂。这是一项煞费苦心的精确工作，但它标志着宇宙学终于成为一门真正的科学。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Testing modified gravity with cosmic shear

DOI：
10.1093/mnras/stv2120
发表时间：
2015-06
期刊：
Monthly Notices of the Royal Astronomical Society
影响因子：
4.8
作者：
J. Harnois-D'eraps;D. Munshi;P. Valageas;L. Waerbeke;P. Brax;P. Coles;L. Rizzo
通讯作者：
J. Harnois-D'eraps;D. Munshi;P. Valageas;L. Waerbeke;P. Brax;P. Coles;L. Rizzo

The morphology of the thermal Sunyaev-Zel'dovich sky The morphology of the y-sky

Sunyaev-Zeldovich 热天空的形态 y 天空的形态