【摘要】：在這篇碩士學(xué)位論文中,我們基于膜世界理論和全息暗能量在高維情況下的推廣,研究了兩個(gè)新的暗能量模型。 首先,我們研究DGP膜世界中的高維全息暗能量模型。在此模型中,我們用5維黑洞對全息暗能量的能量密度作紫外截?cái)�。我們發(fā)現(xiàn),當(dāng)這個(gè)模型中的參數(shù)取為某些特殊值時(shí),此模型分別轉(zhuǎn)化為標(biāo)準(zhǔn)的DGP膜世界模型和龔云貴等人所提出的修正的全息暗能量模型。而且我們發(fā)現(xiàn)當(dāng)取哈勃視界為紅外截?cái)鄷r(shí),這個(gè)模型等效于調(diào)整標(biāo)準(zhǔn)DGP模型的超越尺度。在將未來事件視界取為紅外截?cái)嗟那闆r下,我們用數(shù)值的方法得到了全息暗能量的相對密度、有效態(tài)參數(shù),和宇宙減速因子隨紅移的演化曲線,并且發(fā)現(xiàn)在自加速分支上有效態(tài)參數(shù)可以小于-1/3 ,并且在自加速非自加速兩個(gè)分支中,有效暗能量都可以驅(qū)使宇宙加速膨脹。這和原始DGP模型是不同的,在原始DGP模型中只有自加速分支可以加速膨脹。 我們進(jìn)而取定其中一個(gè)參數(shù)并且取另外的參數(shù)為幾個(gè)不同的值,通過分析我們發(fā)現(xiàn),在自加速分枝,有效態(tài)參數(shù)可以小于-1。這表明宇宙可能會(huì)終結(jié)于一個(gè)大撕裂的奇點(diǎn)。 然后,我們考慮一種物質(zhì)與能量存在相互作用的高維全息暗能量模型。我們假設(shè)相互作用項(xiàng)跟宇宙總能量密度成正比,并分別討論了用哈勃視界和未來事件視界作紅外截?cái)鄡煞N情況下相對密度、有效態(tài)參數(shù),和宇宙減速因子的宇宙學(xué)演化性質(zhì)。在取哈勃視界作為紅外截?cái)鄷r(shí),我們發(fā)現(xiàn)耦合常數(shù)只能取為零或負(fù)數(shù)。這種情況下,宇宙會(huì)隨著紅移z的減小而進(jìn)入一個(gè)加速膨脹的狀態(tài),并且有效態(tài)參數(shù)不會(huì)小于-1,這意味著在取哈勃視界做紅外截?cái)嗟那闆r下,模型避免了宇宙大撕裂的命運(yùn)。在取未來事件視界作為紅外截?cái)嗟那闆r下,我們得到了一組宇宙動(dòng)力學(xué)方程,對此方程組的定性分析表明,它唯一的奇點(diǎn)是一個(gè)鞍點(diǎn)。
[Abstract]:In this master's thesis, we study two new dark energy models based on the theory of film world and the generalization of holographic dark energy in high dimension. First, we study the high dimensional holographic dark energy model in the DGP film world. In this model, we use 5 dimensional black hole to cut off the energy density of holographic dark energy. We find that when the parameters in the model are taken as some special values, the model is transformed into the standard DGP film world model and the modified holographic dark energy model proposed by Gong Yungui and others. Furthermore, we find that the model is equivalent to adjusting the transcendental scale of the standard DGP model when the Hubble horizon is taken as infrared truncation. When the future event horizon is truncated by infrared, the relative density of holographic dark energy, the effective state parameters, and the evolution curve of cosmic deceleration factor with redshift are obtained by numerical method. It is also found that the effective state parameter on the self-accelerating branch can be less than -1 / 3, and in the self-accelerating non-self-accelerating branch, the effective dark energy can drive the universe to accelerate expansion. This is different from the original DGP model, in which only self-accelerating branching can accelerate expansion. We then determine one of the parameters and take the other parameters as several different values. Through analysis we find that the effective state parameter can be less than -1 in self-accelerating branching. This suggests that the universe may end up at a gaping singularity. Then we consider a high dimensional holographic dark energy model in which matter and energy interact. We assume that the interaction term is proportional to the total energy density of the universe, and discuss the cosmological evolution properties of the relative density, the effective state parameters, and the cosmic deceleration factor when the Hubble horizon and the future event horizon are used as infrared truncation. When the Hubble horizon is used as the infrared truncation, we find that the coupling constant can only be taken as zero or negative. In this case, the universe will enter a state of accelerated expansion as the redshift z decreases, and the effective state parameter will not be less than -1, which means that when the Hubble horizon is truncated by infrared, The model avoids the fate of the universe being torn apart. When the event horizon is taken as the infrared truncation, we obtain a set of cosmic dynamics equations. The qualitative analysis of the equations shows that its sole singularity is a saddle point.
【學(xué)位授予單位】：上海師范大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2011
【分類號】：P145.9

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 ;Comparison of dark energy models:A perspective from the latest observational data[J];Science China(Physics,Mechanics & Astronomy);2010年09期

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本文編號：2316690