有相互作用的广义Chaplygin气体动力学分析及参数拟合

发布时间：2018-01-14 21:27

本文关键词：有相互作用的广义Chaplygin气体动力学分析及参数拟合　出处：《上海师范大学》2016年硕士论文　论文类型：学位论文

更多相关文章： 宇宙加速 GCG 相互作用 参数拟合

【摘要】：对Ia型超新星的观测发现宇宙是加速膨胀的,宇宙加速膨胀即尺度因子的二阶导数a大于0,由弗里德曼方程可知,要使a大于0则需要场方程右边多出一个提供负压强的部分。这个负压强不仅抵消了物质引力产生的减速效果还进一步地使宇宙加速膨胀,这部分称为暗能量。研究表明宇宙学常数和quintessence场可作为暗能量的候选者。然而观测发现暗物质与暗能量在当前量级相同,此即引出了巧合性问题,即为什么当前宇宙的暗物质和暗能量量级相同,是巧合还是必然?基于这个问题,追踪场、K-sessence、Chaplygin气体等模型被提了出来,阅读文献时发现如果用上述几个模型对冷暗物质做一个耦合则会一定程度上缓解巧合性问题。会得出一些与初始条件无关的宇宙学演化模式。而考虑Chaplygin气体与冷暗物质部分相互作用时发现其不仅能缓解巧合性问题,还可以统一暗物质与暗能量,具体表现为宇宙早期a趋向于0时表现出暗物质的性质,晚期时ω趋向于-1(ω为态方程参数)表现出暗能量的性质。本文在解决了自治系统奇性的基础上,对GCG与DM相互作用项最简单的几种情况进行了讨论。分别是及Q=-3βHp8(β为无量纲参数,ρm,ρ8,ρtot分别表示物质密度,Chaplygin气体密度和物质密度与Chaplygin气体密度之和)。分别对各自的自治系统的性质进行了分析,讨论了临界点处的性质,得出了符合宇宙加速膨胀的结果,并与标准的ACDM模型做了比较。
[Abstract]:Observations of type Ia supernovae discovered that the universe is accelerating expansion, the accelerated expansion of the universe is the two derivative of the scale factor of a is greater than 0, by the Freedman equation, to make a more than 0 to the right of a multi field equation provides negative pressure part. The negative pressure not only offset the effect of gravitational deceleration produced the further that the accelerated expansion of the universe, this part is called dark energy. The results indicate that the cosmological constant and the quintessence field can be used as a candidate of dark energy. However, the observation that dark matter and dark energy in the same order of magnitude, which leads to the coincidence problem, that is why the current cosmic dark matter and dark energy in the same order that is a coincidence or a necessity? Based on this problem, tracking field, K-sessence, Chaplygin gas model is proposed, the reading of the literature found that if a coupling of cold dark matter with the model He will to some extent alleviate the coincidence problem. Come about the initial conditions of cosmological evolution mode. And considering the Chaplygin gas and the cold dark matter interaction and found that it can not only alleviate the coincidence problem, can also unified the dark matter and dark energy, the specific performance of the early universe when a tends to 0 the nature of dark matter, late tend to -1 (omega Omega for equation of state parameters) exhibit the properties of dark energy. In the base of solving the singular autonomous system, GCG on the interaction between DM and the most simple situations are discussed respectively. And Q=-3 Hp8 (beta beta the dimensionless parameters, P M, P 8, P tot respectively matter density, Chaplygin density and the material density and the density of Chaplygin gas and) respectively. The nature of their respective autonomous systems are analyzed, discussed the nature of the critical point, the character The result of the accelerated expansion of the universe is compared with the standard ACDM model.

【学位授予单位】：上海师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P159

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