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Crossing the phantom divide line in universal extra dimensions
New Astronomy ( IF 1.9 ) Pub Date : 2020-10-01 , DOI: 10.1016/j.newast.2020.101406
Nasr Ahmed , Anirudh Pradhan

We investigate the cosmic acceleration and the evolution of dark energy across the cosmological constant boundary in universal extra dimensions UED. We adopt an empirical approach to solve the higher-dimensional cosmological equations so that the deceleration parameter $q$ is consistent with observations. The expressions for the jerk and deceleration parameters are independent of the number of dimensions $n$. The behavior of pressure in $4$D shows a positive-to-negative transition corresponding to the deceleration-to-acceleration cosmic transition. This pressure behavior helps in providing an explanation to the cosmic deceleration-acceleration transition although the reason behind the transition itself remains unknown. In the conventional $4$D cosmology, there is a no-go theorem prevents the EoS parameter of a single perfect fluid in FRW geometry to cross the $\omega=-1$ boundary. The current model includes a single homogenous but anisotropic perfect fluid in a homogenous FRW metric with two different scale factors in the ordinary $4$D and the UED. In contrast to the conventional $4$D cosmology, we have found that the dark energy evolution in UED shows $\omega=-1$ crossing. however, the no-go theorem is still respected in $4$D where the EoS parameter doesn't cross the $\omega=-1$ boundary.

中文翻译:

跨越通用额外维度中的幻影分界线

我们研究了宇宙加速和暗能量在通用额外维度 UED 中跨越宇宙常数边界的演化。我们采用经验方法来求解高维宇宙学方程,使减速参数 $q$ 与观测结果一致。jerk 和 deceleration 参数的表达式与维数 $n$ 无关。$4$D 中的压力行为显示了对应于减速到加速的宇宙过渡的正到负过渡。这种压力行为有助于解释宇宙减速-加速转变,尽管转变背后的原因仍然未知。在传统的 4 美元 D 宇宙学中,有一个不通过定理阻止 FRW 几何中单个完美流体的 EoS 参数越过 $\omega=-1$ 边界。当前模型包括在同质 FRW 度量中的单一同质但各向异性完美流体,在普通 $4$D 和 UED 中具有两个不同的比例因子。与传统的 $4$D 宇宙学相反,我们发现 UED 中的暗能量演化显示 $\omega=-1$ 交叉。然而,在 $4$D 中仍然遵守 no-go 定理,其中 EoS 参数不跨越 $\omega=-1$ 边界。我们发现UED中暗能量演化显示$\omega=-1$交叉。然而,在 $4$D 中仍然遵守 no-go 定理,其中 EoS 参数不跨越 $\omega=-1$ 边界。我们发现UED中暗能量演化显示$\omega=-1$交叉。然而,在 $4$D 中仍然遵守 no-go 定理,其中 EoS 参数不跨越 $\omega=-1$ 边界。
更新日期:2020-10-01
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