一种新型精质暗能量模型

发布时间：2018-06-16 00:45

本文选题：宇宙学 + 暗能量　；参考：《宁波大学》2013年硕士论文

【摘要】：至今对宇宙微波背景辐射,Ia型超新星以及大尺度结构的观测的结果都表明我们如今的宇宙正经历一个加速膨胀时期。为了解释这种现象,物理学家引入了一种新的能量概念——“暗能量”。其中最简单的一种暗能量模型就是宇宙常数,它是由Einstein在1917年引入用于构造静态宇宙模型,之后由于哈勃在观测中发现宇宙红移现象而被冷落,但是发现宇宙加速膨胀现象后,宇宙学常数被作为暗能量的重要候选者而被重新得到重视。宇宙学常数模型的理论形式简洁,且与观测数据符合的很好,但它也存在巧合性疑难和精细微调疑难两大难题。为了解决这两个问题,物理学家先后提出许多暗能量模型,这其中就包括quintessence模型,k-essence模型,phantom模型,理想流体模型,还有f(R)引力理论,scalar-tensor模型,以及膜宇宙模型。quintessence模型的的状态方程参数不像宇宙常数模型一样是常数,而是在(1,-1)之间可变的,并且该模型不存在巧合性问题。phantom模型与quintessence模型类似,但它满足了暗能量状态参数可以穿过-1的可能性,其不足是可能导致宇宙撕裂。quintom是quintessence模型不(?)phantom模型的两者的一种结合,它同时具备两个模型的一些性质。有两种理论框架可以推出广义相对论,其中一种就是度规形式,而另一种则是palatini形式,但是前者只有度规作为变量,而后者中则把度规和联络分别作为独立变量,这种区别在f(R)为非线性的情况下得到体现,此时,palatini形式得到的场方程是二阶的而非度规形式导出的四阶方程,由于palatini形式在这种情况下能够和太阳系实验结果相符而更具优势。在本文中,我们研究了quintessence标量场与palatini形式下的引力的非最小耦合情况并将这种模型称为一种新的推广的quintessence暗能量模型。我们发现新的推广quintessence模型的有效态方程参数能穿越-1分割线,并且有围绕-1的振荡特性。另外所得到的宇宙最终将进入一个De-Sitter相。
[Abstract]:Observations of the cosmic microwave background radiation and the large scale structure indicate that our universe is undergoing an accelerated expansion period. To explain this phenomenon, physicists introduced a new concept of energy-dark energy. One of the simplest dark energy models is the cosmic constant, which was introduced by Einstein in 1917 to construct a static cosmic model. It was then ignored because Hubble discovered the redshift phenomenon in the universe, but after the discovery of the accelerating expansion of the universe, Cosmological constants have been revalued as important candidates for dark energy. The theoretical form of the cosmological constant model is simple and in good agreement with the observational data, but it also has two difficult problems: coincidental difficulty and fine fine-tuning difficulty. In order to solve these two problems, physicists have put forward many dark energy models, including the quintessence model, the ideal fluid model, and the scalar-tensor model. And the state equation parameters of the membrane universe model. Quintessence model are not constant as the cosmic constant model, but are variable between 1 ~ 1 ~ 1), and there is no coincidence problem. Phantom model is similar to the quintessence model. However, it satisfies the possibility that dark energy state parameters can pass through -1, and its disadvantage is that it may lead to cosmic tearing. Quintom is a combination of quintessence model and phantom model, and it has some properties of two models at the same time. There are two theoretical frameworks that can be used to deduce general relativity, one is metric form, the other is palatini form, but the former only uses metric as variable, while the latter regards metric and connection as independent variables, respectively. This difference can be found in the case that FG R) is nonlinear, where the field equation obtained in the form of palatini is a fourth-order equation derived from a second-order rather than a metric form, which is more advantageous because the palatini form can agree with the experimental results of the solar system in this case. In this paper, we study the nonminimum coupling between quintessence scalar field and gravity in palatini form and call this model a new generalized quintessence dark energy model. We find that the parameters of the effective equation of state of the new extended quintessence model can traverse the -1 Secant and have oscillatory properties around the -1. The resulting universe will eventually enter a de-Sitter phase.
【学位授予单位】：宁波大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：P159

【共引文献】