arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新，休息一下吧，周末愉快~~
arXiv 1208.4855astro-ph.COgr-qchep-th
收藏

非理想流体中的一致扰动

Consistent perturbations in an imperfect fluid

Ignacy Sawicki, Ippocratis D. Saltas, Luca Amendola, Martin Kunz

备注：
40 pages plus appendices. v2 reflects version accepted for publication in JCAP (new summary of notation, extra commentary on choice of gauge and frame, extra references to literature)
发表信息：
JCAP01(2013)004
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

我们提出了一个新的处方，分析宇宙学扰动在更一般的标量场暗能量模型的能量动量张量有一个非流体形式。这个类包括Brans-Dicke模型，f（R）重力，动力学重力编织理论和广义伽利略。我们使用流体的直观语言，使我们能够明确地保持对物理和潜在可测量属性的依赖。我们证明，流体动力学并不总是一个有效的描述一般标量场理论描述宇宙学扰动，并提出了一个一致的替代方案，但利用流体语言。我们明确地将这种方法应用于一个工作的例子：k-本质非最小耦合到重力。这是最简单的情况下，捕捉这些基本的新功能的非牛顿流体模型。我们证明了一个新的规模分离制度的流体是完美的和不完美的通用存在。我们得到了这两个制度的暗能量密度扰动的演化方程。该模型还具有其他两个已知的尺度：康普顿尺度与移位对称性的破缺有关，以及我们表明由小标量场扰动的传播速度（即因果关系）决定的金斯尺度，而不是经常使用的压力和能量密度扰动之比的定义。

英文摘要：

We present a new prescription for analysing cosmological perturbations in a more-general class of scalar-field dark-energy models where the energy-momentum tensor has an imperfect-fluid form. This class includes Brans-Dicke models, f(R) gravity, theories with kinetic gravity braiding and generalised galileons. We employ the intuitive language of fluids, allowing us to explicitly maintain a dependence on physical and potentially measurable properties. We demonstrate that hydrodynamics is not always a valid description for describing cosmological perturbations in general scalar-field theories and present a consistent alternative that nonetheless utilises the fluid language. We apply this approach explicitly to a worked example: k-essence non-minimally coupled to gravity. This is the simplest case which captures the essential new features of these imperfect-fluid models. We demonstrate the generic existence of a new scale separating regimes where the fluid is perfect and imperfect. We obtain the equations for the evolution of dark-energy density perturbations in both these regimes. The model also features two other known scales: the Compton scale related to the breaking of shift symmetry and the Jeans scale which we show is determined by the speed of propagation of small scalar-field perturbations, i.e. causality, as opposed to the frequently used definition of the ratio of the pressure and energy-density perturbations.

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。

↑