论文标题
爱因斯坦静态宇宙及其在广义rastall重力中的稳定性
Einstein Static Universe and its Stability in Generalized Rastall Gravity
论文作者
论文摘要
爱因斯坦静态（ES）状态是通过常规宇宙学模型来描述早期宇宙的良好候选者，其中避免了大爆炸奇点。在本研究中，我们在广义rastall Gravity（GRG）的框架中提出了ES解决方案，这是原始Rastall理论的修改版本，其中允许耦合参数在时空坐标方面变化。研究了针对Rastall参数，存在和溶液的相应稳定性引入ANSATZ。我们表明，GRG能够描述宇宙的稳定无奇异状态。还解决了从ES到通货膨胀状态的过渡问题。我们发现，状态参数方程式从位于位于范围内的值| w | <1/3到值W = -1/3的时间变化会导致这种相变。还研究了ES溶液周围的矢量和张量扰动。在GRG的情况下，矢量扰动仍然冷冻，尽管如此，如果Rastall重力常数与Einsteinian One的比率始终超过每种张量的最小值，则男高音扰动可以使ES溶液保持稳定。
The Einstein static (ES) state is a good candidate for describing the very early universe in terms of a regular cosmological model in which the Big Bang singularity is avoided. In the present study we propose an ES solution in the framework of generalized Rastall gravity (GRG), a modified version of original Rastall theory in which the coupling parameter is allowed to vary with respect to the spacetime coordinates. Introducing an ansatz for the Rastall parameter, existence and the corresponding stability of the solutions are investigated. We show that the GRG is capable of describing a stable singularity-free state for the universe. The problem of transition from an ES to an inflationary state is also addressed. We find that a time variation of the equation of state parameter from values lying in the range |w|<1/3 to the value w=-1/3 can give rise to such a phase transition. The vector and tensor perturbations around the ES solution are studied, as well. In the case of GRG, the vector perturbations remain frozen, nevertheless, the tenor perturbations can grow in such a way that the ES solution remains stable provided the ratio of Rastall gravitational constant to the Einsteinian one always exceeds a minimum value for each tensor mode.
