【作者】 李剑丽；

【导师】 凌意；

【作者基本信息】 南昌大学 ， 天体物理， 2010， 硕士

【摘要】 近年来大量的天文观测表明宇宙正在加速膨胀。具有负压强的奇异物质暗能量成为了宇宙的主导成分。它均匀地分布在整个空间中,为宇宙的加速膨胀提供原动力。尽管人们对暗能量有了初步的认识,但是对它本质的了解却不多。暗能量已经成为了物理学研究中最重要的问题之一。论文首先介绍了宇宙学的背景和标准宇宙学模型,然后对几种比较流行的暗能量模型做了简单介绍。接着,主要研究有理想流体存在时标量场的动力学。由一个标量场来推动宇宙加速膨胀的动力学暗能量模型往往会遇到所谓的精细调节以及巧合性问题。为了解决这些问题,可以引入多组分的模型来求解标度解。在本文中,首先介绍标量场暗能量的自治系统,然后着重讨论了时空弯曲下有理想流体存在时快子暗能量的动力学,并求解标度解,通过对标度解的研究,确定它是稳定的还是短暂的。最后分别在开放宇宙和闭合宇宙两种可能的情况下探讨标度解的势具有什么样的形式及其演化。另外,我们也研究和探讨暗能量的存在对行星进动角的影响。发现对于太阳系水星,暗能量对其进动角的贡献大约为总进动角的万分之一。因此,期望通过对水星进动的精密观测,可以推测暗能量的状态函数,并以此作为检验各种暗能量模型的理论依据。最后是总结与展望,对整篇论文进行总结,并展望未来工作。更多还原

【Abstract】 In recent years, numerous measurements all suggest that the universe is currently accelerating and is dominated by a component with negative pressure, which is named as dark energy. It permeates homogenously in all the universe and pushes the accelerated expansion of the universe. Although dark energy has been preliminarily known, its nature still remains mysterious. Dark energy has become one of the most important problems in the research frontier of physics and cosmology.In this thesis, after briefly reviewing the background of cosmology and the standard cosmological model, we present some fashionable dark energy models.After that, we investigate cosmological dynamics of scalar fields in the presence of a barotropic perfect fluid. The dynamical dark energy models driven by a scalar field suffer from the so called fine-tuning problem and coincidence problem, In order to address these problems, one may employ scalar field models exhibiting scaling solutions. Here we first explain the property of an autonomous system before entering the detailed analysis. Then we present the associated equations of motion for the tachyon field including the background fluid in spatially curved FRW universe and obtain the scaling solutions. Furthermore, by investigating the nature of scaling solutions, we determine whether such behavior is stable or just a transient feature. Then we turn to construct the scalar potential leading to such scaling solutions. In particular, its asymptotical forms are obtained in various circumstances for spatially open and closed universe respectively.In chapter four, we are interested in the impact of dark energy on the perihelion shift of planets. For Mercury, we find an additional contribution due to dark energy, which is approximately 1/10000 of the total angular of the perihelion shift. Thus, it is possible to determine the equation of state of dark energy by observing the perihelion shift of Mercury. Furthermore, the conclusion may be helpful for checking up the dark energy models.Chapter Fiver is both a conclusion and a prospect. It sums up the entire dissertation, and looks into the future work.更多还原