混合和对数遥平行引力中的加速宇宙
Accelerating Universe in Hybrid and Logarithmic Teleparallel Gravity
摘要：
遥平行引力是一种修正的引力理论，其中作用量中基本几何的里奇标量$R$被任意函数形式的挠率标量$T$取代。这样一来，由于$T$只包含维耳拜因的一阶导数，$% f(T)$引力中的宇宙学就大大简化了。本文利用这一吸引人的性质$f(T)$重力和目前的宇宙学场景的混合和对数远程并行重力模型的形式$% f=e^{mT}T^n $和$f=D\log(bT)$分别，其中$m$，$n$，$D$和$b$的自由参数约束，以满足后期的时间加速度。我们采用了一个很好的动机参数化的减速参数只有一个自由度的约束与$χ^{2}$测试从57个数据点的哈勃数据集的红移范围内$0.07<z<2.36$，获得的压力，密度和EoS参数的表达的teleparlate重力模型，并研究其时间演化。我们发现减速参数经历一个签名翻转的$χ^{2}$值的自由参数在$z_{tr}\simeq0.6$，这是符合最新的普朗克测量。接下来，我们提出了一些几何诊断的参数化，以了解暗能量的性质及其偏离$Λ$ CDM宇宙学。最后，我们研究了能量条件，以检查参数空间的一致性，两个远程平行引力模型。我们发现SEC违反这两个模型，这是一个必不可少的配方，以获得一个加速宇宙。
英文摘要：
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=e^{mT}T^n $ and $f=D\log(bT)$ 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 $χ^{2}$ 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 $χ^{2}$ value of the free parameter at $z_{tr}\simeq0.6$ 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 $Λ$CDM 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.
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