基于DESI-DR2观测检验f(R,T)引力框架下的体黏度
Testing the bulk viscosity within the f(R,T) gravity in light of DESI-DR2 observations
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中文总结 AI 辅助
该研究基于DESI-DR2观测，检验f(R,T)引力框架下的体黏度，构建两种黏性模型并通过MCMC约束参数，结果显示模型A拟合略优于$\Lambda$CDM但BIC仍倾向于标准模型。
中文摘要 AI 辅助
我们在f(R,T)引力框架下研究体黏度的宇宙学含义，采用线性模型$f(R,T)=R+2\lambda T$，其中$\lambda$表征物质-几何耦合。假设宇宙为均匀且各向同性的弗里德曼-勒梅特-罗伯逊-沃尔克（FLRW）宇宙，我们在两种不同场景下推导哈勃参数的解析表达式：模型A对应无压黏性流体（物态方程参数$\omega=0$），模型B将物态方程（EoS）参数视为自由参数。通过马尔可夫链蒙特卡洛分析对宇宙学参数进行约束。结果表明，两种黏性f(R,T)模型均能极好地描述当前宇宙膨胀历史，且与组合观测数据兼容。根据修正赤池信息准则（AICc），模型A略优于标准宇宙学模型（$\Lambda$CDM），这反映出仅增加一个自由参数即可实现拟合度的提升；而贝叶斯信息准则（BIC）因对模型复杂度的惩罚更强，仍倾向于更简单的$\Lambda$CDM模型。尽管模型B给出的最小$\chi^2$最低，但该提升幅度过小，不足以证明引入额外自由参数的合理性，根据AICc其统计性能与$\Lambda$CDM相当，而根据BIC则不如$\Lambda$CDM。
英文摘要
We investigate the cosmological implications of the bulk viscosity within the framework of $f(R,T)$ gravity by considering the linear model $f(R,T)=R+2λT$, where $λ$ characterizes the matter--geometry coupling. Assuming a homogeneous and isotropic Friedmann--Lemaître--Robertson--Walker Universe, we derive analytical expressions for the Hubble parameter in two different scenarios: model A, corresponding to a pressureless viscous fluid ($ω=0$), and model B, where the equation of state (EoS) parameter is treated as a free parameter. The cosmological parameters are constrained through a Markov Chain Monte Carlo analysis. The results show that both viscous $f(R,T)$ models provide an excellent description of the current expansion history and remain compatible with the combined observational data. Model A is slightly favored over the standard cosmological model ($Λ$CDM) according to AICc, reflecting the improved fit achieved with only one additional free parameter. In contrast, the BIC continues to favor the simpler $Λ$CDM model owing to its stronger penalty on model complexity. Although model B yields the lowest minimum $χ^2$, the improvement is too small to justify the introduction of an additional free parameter, resulting in a statistical performance comparable to $Λ$CDM according to the AICc but less favorable according to the BIC.
发表机构
- Mohammed I University（穆罕默德一世大学）
- Faculty of Applied Sciences of Nador, Mohammed I University（纳多尔应用科学学院，穆罕默德一世大学）
- Faculty of Sciences, Mohammed I University（理学院，穆罕默德一世大学）
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