arXiv 1709.077952017-09-22astro-ph.COgr-qchep-th

暗能量的有效描述：从理论到唯象

An effective description of dark energy: from theory to phenomenology

Michele Mancarella

备注：: PhD thesis, defended on June 27th,2017 with original title "Tests de cohérence de l'Univers et reliques cosmiques"

摘要：

在过去的几十年里，出现了一个宇宙学模型，它可以通过广泛的尺度来拟合观测结果。它的名称是$Λ$ CDM。然而，仍然有一些具有挑战性的问题仍然没有得到这个模型的回答，例如是什么导致了宇宙的加速膨胀，并且已经提出了许多替代方案。本文提出了一种新的方法来检验这种被称为“暗能量有效理论“的模型。它适用于所有通过增加单个标量自由度来修改广义相对论的模型，称为“标量张量理论”。在第一章中，我总结了目前已知的最一般的此类理论，称为“简并高阶标量张量”（DHost）理论。第二章介绍了暗能量的有效理论。第三章的主题是物质与引力扇区之间的一般耦合。第四章详细分析了不同类型理论的稳定性。值得注意的是，我表明，最一般的理论类免费的不稳定性减少到所谓的Horndeski和超越Horndeski理论，到一个非最小的耦合问题。本论文的另一个目的是研究偏离$Λ$ CDM的可观测效应。在第五章中，我考虑了暗物质和暗能量之间相互作用的可能性，并分析了未来调查对理论自由参数的约束力。第六章着重于物质与标量场之间存在动力学混合的理论的观测效应。这就产生了一种特殊的、潜在的可观察到的效应，即在大尺度结构尺度上引力的减弱。

英文摘要：

In the last decades, a cosmological model that fits observations through a vast range of scales emerged. It goes under the name of $Λ$CDM. However, there are still challenging questions that remain unanswered by this model, such as what causes the observed accelerated expansion of the universe, and many alternatives have been proposed. This thesis concerns an approach to test such models known as "Effective Theory of Dark Energy" . It applies to all models where general relativity is modified by adding a single scalar degree of freedom, called "scalar-tensor theories". In Chapter 1 I summarise the most general class of such theories currently known, called "Degenerate higher-Order Scalar-Tensor" (DHOST) theories. In Chapter 2, I introduce the effective theory of dark energy. The inclusion of a general coupling between matter and the gravitational sector is the subject of Chapter 3. Chapter 4 analyses in details the stability of different classes of theories. Notably, I show that the most general class of theories free from instabilities reduces to the so-called Horndeski and beyond-Horndeski theories, up to a non minimal coupling to matter. Another goal of the thesis is to study the observable effects of deviations from $Λ$CDM. In Chapter 5, I consider the possibility of an interaction between dark matter and dark energy and I analyse the constraining power of future surveys on the free parameters of the theory. Chapter 6 focuses on the observational effects of theories where a kinetic mixing between matter and the scalar field exists. This gives a peculiar and potentially observable effect, namely the weakening of gravity at large scale structure scales.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

摘要：

英文摘要：

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