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arXiv 2003.14216gr-qc
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非最小耦合爱因斯坦-麦克斯韦引力理论的Bianchi I度规解

Bianchi I metric solutions with nonminimally coupled Einstein-Maxwell gravity theory

Hossein Ghaffarnejad, Hoda Gholipour

摘要:

本文利用Bianchi I型均匀各向异性的背景度规,在局部笛卡尔坐标系的$x$方向上具有圆柱对称性,求解了非最小耦合Einstein-Maxwell引力场的度规场方程。为此,我们选择长波长的电磁波,其中波的空间依赖性在膨胀持续时间可以忽略不计。研究电磁矢量势对时空扩展标度因子各向异性轨迹的方向性影响。这个问题只在德西特暴胀时期检查,因为它在宇宙膨胀中的重要性。应用动力系统方法研究了两种不同情况下宇宙系统的稳定性:(a)电磁矢势方向平行于时空的$x$方向;(b)电磁矢势方向垂直于时空的$x$方向.我们得到了在稳定的临界点的一些得到的暴胀解的电磁波表现为暗能量的情况下$a$和$b$的各向异性是可以忽略的膨胀的宇宙,而有一些稳定的临界点的情况下$b$的暴胀稳定的解决方案,其中的电磁波表现为重子可见物质与非零各向异性。

英文摘要:

By using Bianchi I type of homogenous and anisotropic background metric having cylindrical symmetry in $x$ direction of a local cartesian coordinates system, we solve metric field equations for a non-minimally coupled Einstein-Maxwell gravity. To do so we choose long wavelength EM waves where spatial dependence of the waves are negligible at the expansion duration. Motivation of this work is study directional effects of the EM vector potential on anisotropy trajectory of the space time expansion scale factor. This problem is checked just for de Sitter inflationary epoch because of its importance in the expansion of the universe. By applying the dynamical system approach we investigate stability nature of the cosmic system in two different cases: (a) direction of the EM vector potential is parallel to $x$ direction of the spacetime and (b) it is perpendicular to $x$ direction. We obtained at stable critical points for some of obtained inflationary solutions the EM waves behave as dark energy in cases $a$ and $b$ where the anisotropy is negligible by expanding of the universe while there are some stable critical points with inflationary stable solutions in case $b$ for which the EM waves behave as baryonic visible matter with non-vanishing anisotropy.

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