arXiv 1902.069782019-02astro-ph.COgr-qc

在宇宙尺度上测量重力

Measuring gravity at cosmological scales

Luca Amendola, Dario Bettoni, Ana Marta Pinho, Santiago Casas

备注：: Review paper. Clarified some aspects and added new references
DOI：: 10.3390/universe6020020

摘要：

这篇论文是一个教学介绍重力模型，以及如何通过宇宙学观测来约束它们。我们专注于Horndeski标量张量理论和可以用最少的假设测量的量。广义相对论的替代或扩展从它的早期就被提出了。由于洛夫洛克定理，在四维中修改重力通常意味着增加新的自由度。最简单的方法是包括一个耦合到曲率张量项的标量场。在不引起奥斯特罗格拉茨基不稳定性的情况下，最一般的方法是霍恩德斯基拉格朗日量及其扩展。因此，检验引力，用最简单的话来说，就是检验霍恩代斯基拉格朗日量。由于局域引力实验总是可以通过假设某种屏蔽机制或重子是去耦的，甚至修正引力的效应只在早期可见来逃避，因此我们需要在宇宙晚期（大尺度结构）和宇宙早期（宇宙微波背景）用宇宙学观测来检验引力。在这项工作中，我们审查的基本工具，以测试在宇宙尺度的引力，侧重于模型无关的测量。

英文摘要：

This paper is a pedagogical introduction to models of gravity and how to constrain them through cosmological observations. We focus on the Horndeski scalar-tensor theory and on the quantities that can be measured with a minimum of assumptions. Alternatives or extensions of General Relativity have been proposed ever since its early years. Because of Lovelock theorem, modifying gravity in four dimensions typically means adding new degrees of freedom. The simplest way is to include a scalar field coupled to the curvature tensor terms. The most general way of doing so without incurring in the Ostrogradski instability is the Horndeski Lagrangian and its extensions. Testing gravity means therefore, in its simplest term, testing the Horndeski Lagrangian. Since local gravity experiments can always be evaded by assuming some screening mechanism or that baryons are decoupled, or even that the effects of modified gravity are visible only at early times, we need to test gravity with cosmological observations in the late universe (large-scale structure) and in the early universe (cosmic microwave background). In this work we review the basic tools to test gravity at cosmological scales, focusing on model-independent measurements.

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摘要：

英文摘要：

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