论文标题
$ f(t)$宇宙学:从伪 - 爆炸到伪里
$f(T)$ cosmology: From Pseudo-Bang to Pseudo-Rip
论文作者
论文摘要
我们研究了$ f(t)$宇宙学的框架中的完整宇宙演变。我们首先研究运动学级别的要求,并引入了具有必要特征的简单比例因子。对阶段肖像进行详细分析,我们表明宇宙从尺度因子为零的相位开始的无限过去开始,但哈勃参数变为常数,并且其导数为零。由于这些功能类似于伪核命运的功能,但以恢复方式,我们将此初始阶段称为伪爆。然后,宇宙在第一个通货膨胀阶段演变,宇宙学的周转和反弹,此后我们拥有第二个通货膨胀状态,并成功退出。随后,我们获得了标准的热历史以及辐射,物质和延迟加速时期的序列,表明宇宙将导致永恒的伪核相。最后,利用$ f(t)$ gravity的场方程为二阶,因此相应的自主动力系统是一维的,我们结合了上述运动学特征,并且我们重建了可以动态生成伪爆发式宇宙学场景的特定$ f(t)$形式。最后,我们检查了原始波动的演变,表明它们最初是亚匹配物,并且我们表明,总流体在幻影交叉点上没有表现出任何奇异行为,而扭转液则将其作为II型单型相位体验。
We investigate the complete universe evolution in the framework of $f(T)$ cosmology. We first study the requirements at the kinematic level and we introduce a simple scale factor with the necessary features. Performing a detailed analysis of the phase portrait we show that the universe begins in the infinite past from a phase where the scale factor goes to zero but the Hubble parameter goes to a constant, and its derivative to zero. Since these features resemble those of the Pseudo-Rip fate but in a reverted way, we call this initial phase as Pseudo-Bang. Then the universe evolves in a first inflationary phase, a cosmological turnaround and a bounce, after which we have a second inflationary regime with a successful exit. Subsequently we obtain the standard thermal history and the sequence of radiation, matter and late-time acceleration epochs, showing that the universe will result in an everlasting Pseudo-Rip phase. Finally, taking advantage of the fact that the field equations of $f(T)$ gravity are of second order, and therefore the corresponding autonomous dynamical system is one dimensional, we incorporate the aforementioned kinematic features and we reconstruct the specific $f(T)$ form that can dynamically generate the Pseudo-Bang cosmological scenario. Lastly, we examine the evolution of the primordial fluctuations showing that they are initially sub-horizon, and we show that the total fluid does not exhibit any singular behaviour at the phantom crossing points, while the torsional fluid experiences them as Type II singular phases.