Bianchi型$VI_{0}$时空中各向异性流体加速暗能量模型
Accelerating dark energy models with anisotropic fluid in Bianchi type-$VI_{0}$ space-time
摘要：
越来越多的证据表明，需要一个几何形状，类似Bianchi形态来解释所观察到的各向异性的WMAP数据的动机，我们讨论了一些功能的Bianchi型$VI_{0}$宇宙中存在的流体，挥舞着各向异性状态方程（EoS）参数在广义相对论。提出了Bianchi型$VI_{0}$时空中两个各向异性流体加速暗能量模型。要占上风的确定性解决方案，我们选择的比例因子$a(t) = \sqrt{t^{n}e^{t}}$，它产生一个随时间变化的减速参数（DP），代表一类模型，产生的宇宙从早期的减速阶段到最近的加速阶段的过渡。在适当的条件下，各向异性模型更接近于各向同性模型。发现暗能量$ω$的EoS与时间有关，其存在范围与最近的SNe Ia观测数据符合得很好（Knop等人，2003年），超新星Ia数据与CMBR各向异性和星系聚类统计（Tegmark等人，2004年）和来自CMB各向异性的宇宙学数据集的最新组合，高红移Ia型超新星和星系团的光度距离（Hinshaw et al. 2009; Komatsu et al. 2009）。对于不同的$n$值，我们可以得到一类物理上可行的DE模型，宇宙学常数$Λ$是时间的正减函数，并且在较晚的时间（即现在的历元）趋于一个小的正值，这一点被最近的Ia型超新星观测结果所证实.我们还观察到我们的解决方案是稳定的。这两个模型的物理和几何方面也进行了详细讨论。
英文摘要：
Motivated by the increasing evidence for the need of a geometry that resembles Bianchi morphology to explain the observed anisotropy in the WMAP data, we have discussed some features of the Bianchi type-$VI_{0}$ universes in the presence of a fluid that wields an anisotropic equation of state (EoS) parameter in general relativity. We present two accelerating dark energy (DE) models with an anisotropic fluid in Bianchi type-$VI_{0}$ space-time. To prevail the deterministic solution we choose the scale factor $a(t) = \sqrt{t^{n}e^{t}}$, which yields a time-dependent deceleration parameter (DP), representing a class of models which generate a transition of the universe from the early decelerating phase to the recent accelerating phase. Under the suitable condition, the anisotropic models approach to isotropic scenario. The EoS for dark energy $ω$ is found to be time-dependent and its existing range for derived models is in good agreement with the recent observations of SNe Ia data (Knop et al. 2003), SNe Ia data with CMBR anisotropy and galaxy clustering statistics (Tegmark et al. 2004) and latest combination of cosmological datasets coming from CMB anisotropies, luminosity distances of high redshift type Ia supernovae and galaxy clustering (Hinshaw et al. 2009; Komatsu et al. 2009). For different values of $n$, we can generate a class of physically viable DE models.The cosmological constant $Λ$ is found to be a positive decreasing function of time and it approaches to a small positive value at late time (i.e. the present epoch) which is corroborated by results from recent type Ia supernovae observations. We also observe that our solutions are stable. The physical and geometric aspects of both the models are also discussed in detail.
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