全息暗能量的两个模型
发布时间：2018-11-07 14:46
【摘要】：在这篇硕士学位论文中,我们基于膜世界理论和全息暗能量在高维情况下的推广,研究了两个新的暗能量模型。 首先,我们研究DGP膜世界中的高维全息暗能量模型。在此模型中,我们用5维黑洞对全息暗能量的能量密度作紫外截断。我们发现,当这个模型中的参数取为某些特殊值时,此模型分别转化为标准的DGP膜世界模型和龚云贵等人所提出的修正的全息暗能量模型。而且我们发现当取哈勃视界为红外截断时,这个模型等效于调整标准DGP模型的超越尺度。在将未来事件视界取为红外截断的情况下,我们用数值的方法得到了全息暗能量的相对密度、有效态参数,和宇宙减速因子随红移的演化曲线,并且发现在自加速分支上有效态参数可以小于-1/3 ,并且在自加速非自加速两个分支中,有效暗能量都可以驱使宇宙加速膨胀。这和原始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胀。 我们进而取定其中一个参数并且取另外的参数为几个不同的值,通过分析我们发现,在自加速分枝,有效态参数可以小于-1。这表明宇宙可能会终结于一个大撕裂的奇点。 然后,我们考虑一种物质与能量存在相互作用的高维全息暗能量模型。我们假设相互作用项跟宇宙总能量密度成正比,并分别讨论了用哈勃视界和未来事件视界作红外截断两种情况下相对密度、有效态参数,和宇宙减速因子的宇宙学演化性质。在取哈勃视界作为红外截断时,我们发现耦合常数只能取为零或负数。这种情况下,宇宙会随着红移z的减小而进入一个加速膨胀的状态,并且有效态参数不会小于-1,这意味着在取哈勃视界做红外截断的情况下,模型避免了宇宙大撕裂的命运。在取未来事件视界作为红外截断的情况下,我们得到了一组宇宙动力学方程,对此方程组的定性分析表明,它唯一的奇点是一个鞍点。
[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.
【学位授予单位】：上海师范大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：P145.9
本文编号：2316690
[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.
【学位授予单位】：上海师范大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：P145.9
【参考文献】
相关期刊论文 前1条
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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