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arXiv 0903.0452astro-ph.CO
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时变真空的宇宙学意义和结构形成

Cosmological implications and structure formation from a time varying vacuum

Spyros Basilakos

摘要:

研究了真空能量随时间变化的FLRW平坦宇宙模型$Λ(t)$的动力学性质。在这个模型中,我们发现,主要的宇宙学函数,如宇宙的尺度因子和哈勃流定义的指数函数。应用最近的Ia型超新星数据,宇宙微波背景位移参数和重子声振荡跟踪斯隆数字巡天(SDSS)星系的联合似然分析,我们把严格的约束$Λ(t)$方案的主要宇宙学参数。同时,我们将$Λ(t)$模型与传统的$Λ$宇宙学进行了比较,发现前者提供的哈勃展开式与$Λ$宇宙学的哈勃展开式有很好的比较。然而,$Λ(t)$方案预测更强的小尺度动力学,这意味着一个更快的增长速度的扰动相对于通常的$Λ$ -宇宙学,尽管事实上,他们共享相同的状态方程参数。在这个框架中,我们发现,星系团在$Λ(t)$模型似乎形成早于在$Λ$模型。

英文摘要:

We study the dynamics of the FLRW flat cosmological models in which the vacuum energy varies with time, $Λ(t)$. In this model we find that the main cosmological functions such as the scale factor of the universe and the Hubble flow are defined in terms of exponential functions. Applying a joint likelihood analysis of the recent supernovae type Ia data, the Cosmic Microwave Background shift parameter and the Baryonic Acoustic Oscillations traced by the Sloan Digital Sky Survey (SDSS) galaxies, we place tight constraints on the main cosmological parameters of the $Λ(t)$ scenario. Also, we compare the $Λ(t)$ model with the traditional $Λ$ cosmology and we find that the former model provides a Hubble expansion which compares well with that of the $Λ$ cosmology. However, the $Λ(t)$ scenario predicts stronger small scale dynamics, which implies a faster growth rate of perturbations with respect to the usual $Λ$-cosmology, despite the fact that they share the same equation of state parameter. In this framework, we find that galaxy clusters in the $Λ(t)$ model appear to form earlier than in the $Λ$ model.

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