arXiv 0809.45562008-09-26astro-phgr-qchep-th

通过大爆炸的宇宙学扰动

Cosmological perturbations through the big bang

David Wands

备注：: 13 pages, latex, no figures. To appear in Adv Sci Lett, special issue on Quantum Gravity, Cosmology amd Black Holes

摘要：

已经提出了几种方案，其中原始扰动可能起源于量子真空涨落，其相位对应于大爆炸之前的坍缩阶段（在爱因斯坦框架中）。本文简要回顾了三种能在坍缩过程中产生标度不变谱的模型：（1）无压坍缩过程中的曲率扰动，（2）大爆炸前情形中的轴子场扰动，（3）多场爆炸坍缩过程中的快子场。在分离宇宙的图景中，人们可以推导出广义微扰方程来描述大尺度微扰通过半经典反弹的演化，假设一个大尺度极限，其中非均匀微扰可以用局部均匀斑块来描述。对于绝热扰动，在大尺度上存在守恒曲率扰动，而等曲率扰动可以通过大尺度上的非绝热压力扰动改变曲率扰动。不同的大尺度结构起源模型导致不同的观测预言，包括引力波和非高斯性。

英文摘要：

Several scenarios have been proposed in which primordial perturbations could originate from quantum vacuum fluctuations in a phase corresponding to a collapse phase (in an Einstein frame) preceding the Big Bang. I briefly review three models which could produce scale-invariant spectra during collapse: (1) curvature perturbations during pressureless collapse, (2) axion field perturbations in a pre big bang scenario, and (3) tachyonic fields during multiple-field ekpyrotic collapse. In the separate universes picture one can derive generalised perturbation equations to describe the evolution of large scale perturbations through a semi-classical bounce, assuming a large-scale limit in which inhomogeneous perturbations can be described by locally homogeneous patches. For adiabatic perturbations there exists a conserved curvature perturbation on large scales, but isocurvature perturbations can change the curvature perturbation through the non-adiabatic pressure perturbation on large scales. Different models for the origin of large scale structure lead to different observational predictions, including gravitational waves and non-Gaussianity.

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摘要：

英文摘要：

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