论文标题
从弹跳到黑暗能源时代,$ f(r)$重力
From a Bounce to the Dark Energy Era with $F(R)$ Gravity
论文作者
论文摘要
在这项工作中,我们考虑了一种宇宙学场景,在这种情况下,宇宙最初具有类似弹跳的行为,因此,它反弹后,它在占主导地位的事物之后会减速,如进化,并且在很大的积极时期,它在加速阶段经历了。我们的目的是在$ f(r)$重力理论的背景下研究这种演变,并与最近的观察结果进行定量面对。使用几种重建技术,我们在分析中分析了$ f(r)$重力的形式,分别在宇宙的两个极端阶段,尤其是在弹跳附近和晚期时代。通过这种分析结果并通过使用适当的边界条件,我们可以在数值上求解$ f(r)$引力方程,以确定$ f(r)$的形式,以在宇宙时间的广泛值中。数值解决的$ f(r)$重力实现了宇宙的某些宇宙时代的统一,特别是从非偏见到以物质为主时代,从统治着物质到较晚的时间到较晚的深色能量时期。相应地,发现了宇宙的哈勃参数和有效状态参数方程,并讨论了模型的几个定性特征。在弹跳的两侧,哈勃半径渐近地占据零,这导致弹跳点附近的原始曲率扰动模式的产生。相应地,我们计算弹跳点附近的标量和张量扰动功率谱,因此,我们确定了可观察的数量,例如标量曲率扰动的光谱指数,张量表与尺度的比率,因此,我们直接与最新模型面对最新的Planck的观察。此外,$ f(r)$重力暗能量时期面临着sne-ia+bao+h(z)+cmb数据。
In this work we consider a cosmological scenario in which the Universe contracts initially having a bouncing-like behavior, and accordingly after it bounces off, it decelerates following a matter dominated like evolution and at very large positive times it undergoes through an accelerating stage. Our aim is to study such evolution in the context of $F(R)$ gravity theory, and confront quantitatively the model with the recent observations. Using several reconstruction techniques, we analytically obtain the form of $F(R)$ gravity in two extreme stages of the universe, particularly near the bounce and at the late time era respectively. With such analytic results and in addition by employing appropriate boundary conditions, we numerically solve the $F(R)$ gravitational equation to determine the form of the $F(R)$ for a wide range of values of the cosmic time. The numerically solved $F(R)$ gravity realizes an unification of certain cosmological epochs of the universe, in particular, from a non-singular bounce to a matter dominated epoch and from the matter dominated to a late time dark energy epoch. Correspondingly, the Hubble parameter and the effective equation of state parameter of the Universe are found and several qualitative features of the model are discussed. The Hubble radius goes to zero asymptotically in both sides of the bounce, which leads to the generation of the primordial curvature perturbation modes near the bouncing point. Correspondingly, we calculate the scalar and tensor perturbations power spectra near the bouncing point, and accordingly we determine the observable quantities like the spectral index of the scalar curvature perturbations, the tensor-to-scalar ratio, and as a result, we directly confront the present model with the latest Planck observations. Furthermore the $F(R)$ gravity dark energy epoch is confronted with the Sne-Ia+BAO+H(z)+CMB data.