论文标题
具有幂律术语的全息宇宙学模型中耗散性和非疾病宇宙的演变
Evolution of dissipative and non-dissipative universes in holographic cosmological models with a power-law term
论文作者
论文摘要
即使两个宇宙的背景演变是相同的，与结构地层相关的密度扰动也有望不同。为了阐明两个宇宙之间的差异，使用两种类型的全息宇宙学模型研究了一阶密度扰动。第一种类型是“ $λ（t）$模型”，类似于非散文宇宙的时变$λ（t）$宇宙学。第二种类型是类似于耗散宇宙的散装粘性宇宙学类似的“ BV模型”。为了系统地检查两个不同的宇宙，假设弗里德曼（Robertson-Robertson-walker）模型是后期宇宙的平面模型，则将与$ h^α$成比例的幂术语适用于$λ（t）$和BV（散装 - 粘合式）模型。在这里，$ h $是哈勃参数，$α$是一个自由参数，其值为实际数字。 $λ（t）$ - $ h^α$和bv- $ h^α$模型用于检查物质的一阶密度扰动，其中两个模型的背景演变等效。此外，讨论了这两个模型的热力学约束，重点是宇宙中熵的最大化，扩展了先前的分析[Phys。 Rev. D 100，123545（2019）（Arxiv：1911.08306）; 102，063512（2020）（Arxiv：2006.09650）]。因此，与bv- $ h^α$模型相比，发现小$ |α| $值的$λ（t）$ - $ h^α$模型与观察结果一致，并满足热力学约束。结果表明，$λ（t）$ - $ h^α$模型与Lambda Cold Dark Matter模型相似的非解剖世界很可能受到青睐。
Density perturbations related to structure formations are expected to be different in dissipative and non-dissipative universes, even if the background evolution of the two universes is the same. To clarify the difference between the two universes, first-order density perturbations are studied, using two types of holographic cosmological models. The first type is a "$Λ(t)$ model" similar to a time-varying $Λ(t)$ cosmology for the non-dissipative universe. The second type is a "BV model" similar to a bulk viscous cosmology for the dissipative universe. To systematically examine the two different universes, a power-law term proportional to $H^α$ is applied to the $Λ(t)$ and BV (bulk-viscous-cosmology-like) models, assuming a flat Friedmann--Robertson--Walker model for the late universe. Here, $H$ is the Hubble parameter and $α$ is a free parameter whose value is a real number. The $Λ(t)$-$H^α$ and BV-$H^α$ models are used to examine first-order density perturbations for matter, in which the background evolution of the two models is equivalent. In addition, thermodynamic constraints on the two models are discussed, with a focus on the maximization of entropy on the horizon of the universe, extending previous analyses [Phys. Rev. D 100, 123545 (2019) (arXiv:1911.08306); 102, 063512 (2020) (arXiv:2006.09650)]. Consequently, the $Λ(t)$-$H^α$ model for small $|α|$ values is found to be consistent with observations and satisfies the thermodynamic constraints, compared with the BV-$H^α$ model. The results show that the non-dissipative universe described by the $Λ(t)$-$H^α$ model similar to lambda cold dark matter models is likely favored.
