摘要
自1998年超新星观测发现宇宙加速膨胀以来,暗能量问题已经成为当前天体物理和宇宙学研究中最重要的问题之一。此后关于宇宙微波背景辐射和大尺度结构的测量也进一步支持了1998年的发现。该文首先概述了宇宙学的起源,然后详细介绍了目前解释宇宙加速膨胀机制的三类模型,包括各模型提出的动机、存在的优缺点,以及当前的主要进展等.最后对暗能量模型作了总结和展望。
One of the most important issues of modern cosmology concerns the acceleration of the cosmological expansion, which has been discovered by recent supernovae, CMBR and LSS observations. Most attempts have been done to explain this acceleration. Currently there are three kinds of mechanism for cosmic acceleration： （1） Dark energy is regarded as a source of the Einstein field equation. The nature of the dark energy is unknown but it behaves like a fluid with negative pressure, that can drive the universe to accelerate. By focusing our attention on specific examples of dark energy scenarios, we discuss several different candidates for this dark component, namely, ACDM, holographic dark energy model, chaplygin gas model and some scalar field models. Among them ACDM fits the data best. But it is embarrassed by the cosmological constant problem. In this case, people proposed holographic dark energy model, chaplygin gas model, and some scalar field models, however, these models still do not solve the cosmological constant problem thoroughly. （2） The modified gravity theory is considered in the present Hubble scale, in which the acceleration is regarded as the property of the gravity theory, without any exotic negative pressure component. Examples of modified gravity theory include braneworld model and f（R） gravity. The above mentioned two mechanisms are based on the cosmological principle, which considers that our universe is isotropic and homogeneous. （3） The inhomogeneoty of our universe is used to explain the acceleration. This can happen in two ways： （1） locally via backreaction and observational effects, and via large scale inhomogeneity. （2） Small scale inhomogeneity has two effects： The backreaction from small scale inhomogeneity to the large scale geometry can generate a dynamic effect in the effective Friedmann equation for the cosmology; Small scale inhomogeneity has significant effects on the propagation of photons, with potentially important effects on observations.A large scal
出处
《天文学进展》
CSCD
北大核心
2009年第2期129-151,共23页
Progress In Astronomy
基金
国家自然科学基金重点项目(10533010)
关键词
宇宙学
加速膨胀
暗能量
理论模型
cosmology
accelerating expansion
dark energy
theoretical models
