标题： 关于$f(R, T)$引力中粘性流体状态方程的观测限制 显示英文标题

标题： Observational constraints on the equation of state of viscous fluid in $f(R, T)$ gravity

摘要： 本文研究了一种基于粘性$f(R,T)$引力的宇宙学模型，作为暗能量的潜在替代方案。 该模型结合了整体黏性，并通过有效的状态方程进行分析。 我们考虑了最简单的特定模型$f(R,T)=R+\lambda T$，其中$\lambda$为常数。 我们推导出了粘性$f(R,T)$宇宙学模型的精确解，然后利用由31个$H(z)$数据点和1701个Pantheon+超新星数据点组成的组合数据集来确定模型参数的最佳拟合值。 我们发现与观测结果有很好的一致性，尤其是在较高的红移处。 我们分析了模型的能量密度、黏性下的压力、有效状态方程以及减速参数的行为。 结果显示宇宙膨胀从减速阶段过渡到加速阶段，表明宇宙流体中的整体黏性能够有效地产生推动宇宙膨胀所需的负压。 最后，我们探索了状态参量诊断以区分不同的暗能量模型，揭示我们的模型位于拟态区域。 显示英文摘要

摘要： In this paper, we investigate a cosmological model based on viscous $f(R,T)$ gravity as a potential alternative to dark energy. This model incorporates bulk viscosity and is analyzed using an effective equation of state. We consider the simplest specific model, $f(R,T)=R+\lambda T$, where $\lambda$ is a constant. The exact solution of our viscous $f(R,T)$ cosmological model is derived, and then we use the combined datasets consisting of 31 $H(z)$ data points and 1701 Pantheon+ SNe data points to determine the best-fit values of the model parameters. We find good agreement with observations, particularly at higher redshifts. Our model's behavior, including energy density, pressure with viscosity, effective equation of state, and deceleration parameter, is analyzed. It indicates a shift from decelerated to accelerated phases of the universe's expansion, suggesting that bulk viscosity in the cosmic fluid could effectively generate the negative pressure necessary for cosmic expansion. Finally, we explore statefinder diagnostics to differentiate between various dark energy models, revealing that our model resides in the quintessence region.