In this study, we explore the accelerated expansion of the universe within the framework of modified f(Q) gravity. The investigation focus on the role of bulk viscosity in understanding the universe’s accelerated expansion. Specifically, a bulk viscous matter-dominated cosmological model is considered, with the bulk viscosity coefficient expressed as \(\zeta = \zeta _0 \rho H^{-1} + \zeta _1 H \). We consider the power law f(Q) function \(f(Q)=\alpha Q^n \), where \(\alpha \) and n are arbitrary constants and derive the analytical solutions for the field equations corresponding to a flat FLRW metric. Subsequently, we used the combined Cosmic Chronometers (CC)+Pantheon+SH0ES sample to estimate the free parameters of the obtained analytic solution. We conduct Bayesian statistical analysis to estimate the posterior probability by employing the likelihood function and the MCMC random sampling technique, along with the AIC and BIC statistical assessment criteria. In addition, we explore the evolutionary behavior of significant cosmological parameters. The effective equation of state (EOS) parameter predicts the accelerating behavior of the cosmic expansion phase. Further, by the statefinder and Om(z) diagnostic test, we found that our viscous model favors quintessence-type behavior and can successfully describe the late-time scenario.

在这项研究中，我们在修正的 f(Q) 引力框架内探索宇宙的加速膨胀。该研究的重点是体积粘度在理解宇宙加速膨胀中的作用。具体来说，考虑以体粘性物质为主的宇宙学模型，体粘性系数表示为 \(\zeta = \zeta _0 \rho H^{-1} + \zeta _1 H \)。我们考虑幂律 f(Q) 函数 \(f(Q)=\alpha Q^n \)，其中 \(\alpha \) 和 n 是任意常数，并导出对应于平面的场方程的解析解FLRW 度量。随后，我们使用宇宙天文台（CC）+万神殿+SH0ES组合样本来估计所获得的解析解的自由参数。我们采用似然函数和 MCMC 随机抽样技术以及 AIC 和 BIC 统计评估标准进行贝叶斯统计分析来估计后验概率。此外，我们还探索了重要宇宙学参数的演化行为。有效状态方程（EOS）参数预测宇宙膨胀阶段的加速行为。此外，通过statefinder和Om(z)诊断测试，我们发现我们的粘性模型有利于典型的行为，并且可以成功地描述后期场景。