Role of internal space correlations in the dynamics of a higher-dimensional Bianchi type-I universe: Shear scalar and Hubble parameter perspectives

被引:0
|
作者
Katirci, Nihan [1 ]
机构
[1] Dogus Univ, Dept Elect & Elect Engn, TR-34775 Istanbul, Turkiye
关键词
Gravitation; Higher dimensions; Expansion anisotropy; Cosmology; Bianchi type universes; Exact solutions of Einstein field equations; COSMOLOGICAL MODELS; WORMHOLES;
D O I
10.1016/j.jheap.2025.01.002
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We investigate exact solutions of the Einstein field equations in higher-dimensional, spatially homogeneous Bianchi type-I spacetimes, introducing a real parameter A that correlates the expansion rates of external and internal spaces. Extending beyond Robertson-Walker spacetime, our approach includes positive and negative correlations, suggesting a broader and isotropic/anisotropic cosmological model space. Positively correlated dimensions manifest as a cosmological constant at late times, while at early times, they mimic stiff-fluid-like dark energy that dilutes faster than radiation, paralleling early dark energy models. This suggests a pathway for alleviating the Hubble tension by tailoring higher-dimensional dynamics to reduce the sound horizon. When anisotropic expansion is allowed, these models achieve isotropization more efficiently than predicted by Wald's cosmic no-hair theorem. Negative correlations, in contrast, yield a higher-dimensional steady-state universe where the shear scalar remains constant, effectively emulating a negative cosmological constant. These distinct behaviors arise from a simple signature change: positive correlation accelerates shear scalar decay, while negative correlation stabilizes it. We demonstrate that the solutions admit analytic continuation from the Lorentzian to Euclidean regime (t- -ii), revealing a wormhole-like topology that connects two asymptotic regions via a throat, with A- -A.
引用
收藏
页码:382 / 391
页数:10
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