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Accelerating universe in hybrid and logarithmic teleparallel gravity
Physics of the Dark Universe ( IF 5.5 ) Pub Date : 2020-04-15 , DOI: 10.1016/j.dark.2020.100551
Sanjay Mandal , Snehasish Bhattacharjee , S.K.J. Pacif , P.K. Sahoo

Teleparallel gravity is a modified theory of gravity for which the Ricci scalar R of the underlying geometry in the action is replaced by an arbitrary functional form of torsion scalar T. In doing so, cosmology in f(T) gravity becomes greatly simplified owing to the fact that T contains only the first derivatives of the vierbeins. The article exploits this appealing nature of f(T) gravity and present cosmological scenarios from hybrid and logarithmic teleparallel gravity models of the form f=emTTn and f=Dlog(bT) respectively, where m, n, D and b are free parameters constrained to suffice the late time acceleration. We employ a well motivated parametrization of the deceleration parameter having just one degree of freedom constrained with a χ2 test from 57 data points of Hubble data set in the redshift range 0.07<z<2.36, to obtain the expressions of pressure, density and EoS parameter for both the teleparallel gravity models and study their temporal evolution. We find the deceleration parameter to experience a signature flipping for the χ2 value of the free parameter at ztr0.6 which is consistent with latest Planck measurements. Next, we present few geometric diagnostics of this parametrization to understand the nature of dark energy and its deviation from the ΛCDM cosmology. Finally, we study the energy conditions to check the consistency of the parameter spaces for both the teleparallel gravity models. We find the SEC to violate for both the models which is an essential recipe to obtain an accelerating universe.



中文翻译:

混合和对数远平行重力加速宇宙

远平行重力是对Ricci标量的重力修正理论 [R 动作中的基本几何图形被任意形式的扭转标量取代 Ť。这样,宇宙学在FŤ 由于以下事实,重力大大简化了 Ť仅包含vierbeins的一阶导数。这篇文章利用了FŤ 形式的混合和对数远平重力模型产生的重力和当前宇宙学情景 F=ËŤŤñF=d日志bŤ 分别在哪里 ñdb是受约束的自由参数,足以满足后期加速要求。我们对减速度参数采用了动机很好的参数化方法,该参数只有一个自由度受χ2 在红移范围内从Hubble数据集的57个数据点进行测试 007<ž<236,以获取两个遥平行重力模型的压力,密度和EoS参数的表达式,并研究它们的时间演化。我们发现减速度参数经历了信号的翻转χ2 free参数的值位于 žŤ[R06与最新的普朗克测量结果一致。接下来,我们将对这种参数化进行一些几何诊断,以了解暗能量的性质及其与暗能量的偏差。ΛCDM宇宙学。最后,我们研究了能量条件,以检查两个遥平行重力模型的参数空间的一致性。我们发现两种模型都违反了SEC,这是获得加速宇宙的基本方法。

更新日期:2020-04-15
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