【摘要】：本論文對宇宙原初擾動和晚期暗能量的若干問題進行了研究。 我們首先研究了宇宙原初擾動的非高斯性。我們簡單介紹了宇宙學擾動理論,然后我們引入了推廣的多場暴脹模型。我們計算計算了該模型下原初擾動的四點關(guān)聯(lián)函數(shù)。我們發(fā)現(xiàn)該模型下四點關(guān)聯(lián)函數(shù)的貢獻主要來源于兩個方面,一個是單頂點圖,另一個是中間交換一個標量子的雙頂點圖。我們發(fā)現(xiàn)在一般推廣的暴脹模型下,這兩個圖的貢獻都是重要的。我們還分析了該模型下非高斯型的動量位型函數(shù)和非線性參數(shù)。在研究完四點關(guān)聯(lián)函數(shù)之后,我們又介紹了幾類暴脹模型五點函數(shù)和六點函數(shù)的計算,并從中計算出觀測上的預言。 我們研究了一類替代暴脹模型,即物質(zhì)反彈宇宙模型。我們利用“鬼凝聚”標量場來實現(xiàn)物質(zhì)主導的收縮宇宙到大爆炸膨脹宇宙的反彈。我們計算了含有“鬼凝聚”標量場的物質(zhì)收縮宇宙的原初擾動譜,發(fā)現(xiàn)普通物質(zhì)產(chǎn)生的擾動譜仍是一個標度不變譜,而“鬼凝聚”標量場產(chǎn)生藍譜,并且擾動的增長速度要比物質(zhì)的擾動增長速度要慢。 我們對晚期暗能量進行了唯象上的研究。我們計算了全息暗能量的擾動的穩(wěn)定性,研究了幾種不同的全息暗能量模型下宇宙的命運。我們研究了全息氣體模型,該模型下氣體的熵正比于該系統(tǒng)的表面積。當我們把這類氣體模型運用到宇宙學上,我們發(fā)現(xiàn)它可以驅(qū)動宇宙加速膨脹,因此,我們的全息氣體模型可以作為暗能量的一個候選者之一。
[Abstract]:In this paper, we study some problems of the primary disturbance and late dark energy in the universe. We first study the non-Gao Si nature of the primitive disturbance of the universe. We briefly introduce the cosmological perturbation theory, and then we introduce a generalized multifield inflation model. We calculate the four point correlation function of the primitive disturbance under this model. We find that the contribution of the four-point correlation function under this model mainly comes from two aspects: one is a single-vertex graph and the other is a bivertex graph with a scalar quantum. We find that the contribution of these two graphs is important in the generalized inflation model. We also analyze the momentum potential functions and nonlinear parameters of non Gao Si type in this model. After studying the four-point correlation function, we also introduce the calculation of five-point function and six-point function of several kinds of inflating models, and calculate the observational predictions from them. We study a class of alternative inflation models, namely, the cosmic model of material rebound. We use the "ghost condensation" scalar field to achieve a rebound from the material-dominated shrinking universe to the Big Bang expansion universe. We calculate the original perturbation spectrum of the shrinking universe of matter containing the "ghost condensation" scalar field. It is found that the perturbation spectrum produced by ordinary matter is still a scalar invariant spectrum, while the "ghost condensate" scalar field produces the blue spectrum. And the growth rate of disturbance is slower than that of matter. We have carried out phenomenological studies of late dark energy. We calculate the stability of the perturbation of holographic dark energy and study the fate of the universe under several holographic dark energy models. We study a holographic gas model in which the entropy of the gas is proportional to the surface area of the system. When we apply this kind of gas model to cosmology, we find that it can drive the acceleration of expansion of the universe. Therefore, our holographic gas model can be used as a candidate for dark energy.
【學位授予單位】：中國科學技術(shù)大學
【學位級別】：博士
【學位授予年份】：2011
【分類號】：P159

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本文編號：2295122