不同类正则暗能量标量场模型中微扰的演化
Evolution of perturbations in distinct classes of canonical scalar field models of dark energy
摘要：
暗能量必须聚集才能符合等效原理。背景演化可以有效地用标量场或正压流体模拟，流体模型可以用来模拟暗能量的标量场模型中的扰动，尽管该模型在大尺度下会失效。本文研究正则标量场模型中暗能量扰动的演化：解冻模型和冻结模型的分类。暗能量状态方程在这两类模型中的演化是不同的。在冻结模型中，状态方程在早期偏离宇宙学常数。对于解冻模型，暗能量状态方程在早期保持在宇宙学常数附近，只有在晚期才开始偏离宇宙学常数。由于暗能量状态方程在不同时期的演化不同，因此暗能量状态方程在不同时期的演化不同。这些类，暗能量扰动也演变不同。在冻结模型中，由于物态方程在早期偏离宇宙学常数，物质扰动的演化与宇宙学常数模型中的物质扰动有显著差异，而在解冻模型中，物质扰动与宇宙学常数的差异仅出现在晚期。这种差异提供了一个额外的句柄来区分这些模型类别，这种差异应该在ISW效应中表现出来。
英文摘要：
Dark energy must cluster in order to be consistent with the equivalence principle. The background evolution can be effectively modelled by either a scalar field or by a barotropic fluid.The fluid model can be used to emulate perturbations in a scalar field model of dark energy, though this model breaks down at large scales. In this paper we study evolution of dark energy perturbations in canonical scalar field models: the classes of thawing and freezing models.The dark energy equation of state evolves differently in these classes.In freezing models, the equation of state deviates from that of a cosmological constant at early times.For thawing models, the dark energy equation of state remains near that of the cosmological constant at early times and begins to deviate from it only at late times.Since the dark energy equation of state evolves differently in these classes,the dark energy perturbations too evolve differently. In freezing models, since the equation of state deviates from that of a cosmological constant at early times, there is a significant difference in evolution of matter perturbations from those in the cosmological constant model.In comparison, matter perturbations in thawing models differ from the cosmological constant only at late times. This difference provides an additional handle to distinguish between these classes of models and this difference should manifest itself in the ISW effect.
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