arXiv 2007.067902020-07-14gr-qchep-th

$f(R,T)$引力中的晚期粘性宇宙学

Late-Time Viscous Cosmology in $f(R,T)$ Gravity

Simran Arora, Snehasish Bhattacharjee, P. K. Sahoo

备注：: New Astronomy accepted version
发表信息：: New Astronomy, 82 (2021) 101452
DOI：: 10.1016/j.newast.2020.101452

摘要：

本文提出了另一种途径来满足后期加速度的要求，考虑粘性系数为$ζ=ζ_{0}+ ζ_{1} H + ζ_{2} H^{2}$的大体积粘性流体，其中$ζ_{0}, ζ_{1}, ζ_{2}$是$f(R,T)$修正重力框架中的常数。我们假定$f(R,T)$函数形式为$f=R+2αT$，其中$α$为常数。然后，我们解决了场方程的哈勃参数和研究宇宙动力学的运动学变量，如减速，急动，抢购和lerk参数作为宇宙时间的函数。我们观察到的减速参数是高度敏感的$α$，并经历了签名翻转周围$t\sim 10$陀螺仪的$α=-0.179$，这是有利的观察。我们的模型的EoS参数假设在$t_{0}=13.7$陀螺仪上接近$-1$的值，这与最新的普朗克测量结果非常一致。接下来，我们研究了能量条件的演化，发现我们的模型违反了强能量条件，以解释晚期宇宙加速。为了理解由体粘重子流体模拟的暗能量的性质，我们进行了一些几何诊断，如$\{r,s\}$和$\{r,q\}$平面。我们发现这个模型在早期模仿了Chaubergin气体型暗能量模型的性质，而在遥远的未来则是Quintessence类型。最后，我们研究了我们的模型的连续性方程的破坏，并表明，为了解释宇宙加速在目前的时代，能量动量必须违反。

英文摘要：

The article communicates an alternative route to suffice the late-time acceleration considering a bulk viscous fluid with viscosity coefficient $ζ=ζ_{0}+ ζ_{1} H + ζ_{2} H^{2}$, where $ζ_{0}, ζ_{1}, ζ_{2}$ are constants in the framework of $f(R,T)$ modified gravity. We presume the $f(R,T)$ functional form to be $f=R+2αT$ where $α$ is a constant. We then solve the field equations for the Hubble Parameter and study the cosmological dynamics of kinematic variables such as deceleration, jerk, snap and lerk parameters as a function of cosmic time. We observe the deceleration parameter to be highly sensitive to $α$ and undergoes a signature flipping at around $t\sim 10$ Gyrs for $α=-0.179$ which is favored by observations. The EoS parameter for our model assumes values close to $-1$ at $t_{0}=13.7$Gyrs which is in remarkable agreement with the latest Planck measurements. Next, we study the evolution of energy conditions and find that our model violate the Strong Energy Condition in order to explain the late-time cosmic acceleration. To understand the nature of dark energy mimicked by the bulk viscous baryonic fluid, we perform some geometrical diagnostics like the $\{r,s\}$ and $\{r,q\}$ plane. We found the model to mimic the nature of a Chaplygin gas type dark energy model at early times while a Quintessence type in distant future. Finally, we study the violation of continuity equation for our model and show that in order to explain the cosmic acceleration at the present epoch, energy-momentum must violate.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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