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$f(T)$引力中的体黏滞物质：宇宙加速的一条路径

Bulk viscous matter in $f(T)$ gravity: A path to cosmic acceleration

Kairat Myrzakulov, O. Donmez, M. Koussour, S. Muminov, E. Davletov, J. Rayimbaev

备注：
Physics Letters A accepted version
发表信息：
Phys. Lett. A 534, 130232 (2025)
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AI总结：

本研究在$f(T)$远平行引力框架下探究体黏滞系数变化对宇宙演化的影响，通过观测数据约束模型参数，证实该模型可解释宇宙从减速到加速的膨胀转变。

摘要：

本文在$f(T)$远平行引力框架下，研究变化的体黏滞系数$ζ(t)=ζ_{0}+ζ_{1}H$对宇宙演化的影响。我们聚焦两种情形：（i）$ζ_{1} \neq0$和（ii）$ζ_{1} =0$，采用线性$f(T)$模型（$f(T) = αT$，其中$α\neq 0$）推导哈勃参数$H$作为红移$z$的函数。利用$H(z)+Pantheon^{+}+BAO$组合数据集，我们得到了模型参数的观测约束。情形I（$ζ_1 \neq 0$）的最佳拟合值为$H_0=60.0^{+2.0}_{-1.9}$ km/s/Mpc、$α=1.01^{+0.10}_{-0.098}$、$ζ_0=40.1^{+1.9}_{-2.0}$、$ζ_1=0.123^{+0.093}_{-0.088}$；情形II（$ζ_1 = 0$）的最佳拟合值为$H_0=67.5^{+1.3}_{-1.3}$ km/s/Mpc、$α=0.94^{+0.14}_{-0.13}$、$ζ_0=34.7^{+2.0}_{-2.0}$。分析显示减速参数存在转变，表明宇宙膨胀从减速向加速过渡，两种情形对应的当前值分别为$q_{0} \approx -0.49$和$q_{0} \approx -0.32$。宇宙黏滞流体的jerk参数$j(z)$和有效状态方程也支持宇宙加速，其演化轨迹与quintessence（精质）图景一致。这些结果凸显了我们的以体黏滞物质为主的$f(T)$模型在解释宇宙加速方面的潜力。

英文摘要：

In this paper, we investigate the effects of varying bulk viscosity coefficients $ζ(t)=ζ_{0}+ζ_{1}H$ on cosmic evolution within the framework of $f(T)$ teleparallel gravity. We focus on two cases: (i) $ζ_{1} \neq0$ and (ii) $ζ_{1} =0$, deriving the Hubble parameter $H$ as a function of redshift $z$ using a linear $f(T)$ model ($f(T) = αT$ where $α\neq 0$). Using the combined $H(z)+Pantheon^{+}+BAO$ dataset, we obtain observational constraints on model parameters. For Case I ($ζ_1 \neq 0$), best-fit values are $H_0=60.0^{+2.0}_{-1.9}$ km/s/Mpc, $α=1.01^{+0.10}_{-0.098}$, $ζ_0=40.1^{+1.9}_{-2.0}$, and $ζ_1=0.123^{+0.093}_{-0.088}$, while for Case II ($ζ_1 = 0$), they are $H_0=67.5^{+1.3}_{-1.3}$ km/s/Mpc, $α=0.94^{+0.14}_{-0.13}$, and $ζ_0=34.7^{+2.0}_{-2.0}$. The analysis reveals a transition in the deceleration parameter, indicating a shift from deceleration to acceleration of the universe's expansion, with present-day values of $q_{0} \approx -0.49$ and $q_{0} \approx -0.32$ for the respective cases. The jerk parameter $j(z)$ and effective EoS for the cosmic viscous fluid also support the cosmic acceleration, with trajectories aligning with the quintessence scenario. These findings underscore the potential of our $f(T)$ model dominated by bulk viscous matter in explaining cosmic acceleration.

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