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arXiv 1901.04849gr-qc
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Chern-Simons修正引力中的Ricci-Gauss-Bonnet全息暗能量:一个平坦的FLRW quintessence支配宇宙

Ricci-Gauss-Bonnet holographic dark energy in Chern-Simons modified gravity: A flat FLRW quintessence-dominated universe

Nasr Ahmed

摘要:

讨论了最近提出的在Chern-Simons修正引力下的Ricci-Gauss-Bonnet全息暗能量。我们对标度因子$a(t)$的几种一般形式进行了检验,并采用了两种物理上合理的形式,这两种形式已被证明是与观测相一致的。这两种解都预测了宇宙压力演化的符号翻转,在早期减速期间为正,在晚期加速期间为负。这种宇宙压力演化中的符号翻转有助于解释宇宙减速-加速转变,并且在不同背景下的其他宇宙学模型中也出现过。然而,目前的工作表明,需要解释的压力奇异性。状态方程参数$ω(t)$的演化表明两种解具有相同的渐近行为,表明在遥远的未来存在一个五重态主导的宇宙。我们还注意到,在气压变为负值的同时,$ω(t)$变为负值(在$ω=0$处留下减速尘埃主导时代)。同样,在$ω(t)$的行为中还有另一个奇点,它发生在压力奇点的同一宇宙时间。

英文摘要:

We discuss the recently suggested Ricci-Gauss-Bonnet holographic dark energy in Chern-Simons modified gravity. We have tested some general forms of the scale factor $a(t)$, and used two physically reasonable forms which have been proved to be consistent with observations. Both solutions predict a sign flipping in the evolution of cosmic pressure which is positive during the early-time deceleration and negative during the late-time acceleration. This sign flipping in the evolution of cosmic pressure helps in explaining the cosmic deceleration-acceleration transition, and it has appeared in other cosmological models in different contexts. However, the current work shows a pressure singularity which needs to be explained. The evolution of the equation of state parameter $ω(t)$ shows the same asymptotic behavior for both solutions indicating a quintessence-dominated universe in the far future. We also note that $ω(t)$ goes to negative values (leaving the decelerating dust-dominated era at $ω=0$) at exactly the same time the pressure becomes negative. Again, there is another singularity in the behavior of $ω(t)$ which happens at the same cosmic time of the pressure singularity.

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