发表机构
Universidad Mayor; Universidad de Santiago de Chile（乌尼韦尔西达多尔大学; 智利圣地亚哥大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
利用DESI DR2等观测数据检验单模引力中的扩散宇宙学模型，发现其虽拟合略优但信息准则仍偏好ΛCDM，且数据一致支持约20%暗能量预算的非零扩散贡献。
AI 中文摘要
单模引力中的扩散函数会诱导出一个动态的有效宇宙学常数，为近期DESI观测提供了一个有吸引力的框架。在本工作中，我们利用DESI DR2的重子声学振荡测量、Ia型超新星汇编（Pantheon+、DES-Dovekie和DESY5）以及宇宙计时器数据，研究了一类一般性扩散模型的观测可行性。我们发现，在所有考虑的数据集组合中，扩散模型系统性地获得比ΛCDM更低的拟合优度χ²值，表明拟合优度有适度但持续的改善。然而，χ²的减少不足以抵消更大的参数空间，导致标准信息准则倾向于更简单的ΛCDM模型。尽管如此，所有数据集组合一致偏好一个非零的扩散贡献，其约占当前暗能量预算的20%，后验概率P(f_Q>0.05)=96.78%。从观测角度看，扩散模型因此仍然是标准宇宙学情景的一个可行扩展，并激励探索更简单的扩散参数化，特别是在即将到来的高精度宇宙学调查背景下。
英文摘要
Diffusion functions in unimodular gravity induce a dynamical effective cosmological constant, providing an appealing framework in light of recent DESI observations. In this work, we investigate the observational viability of a general class of diffusion models using baryon acoustic oscillation measurements from DESI DR2, Type Ia supernova compilations (Pantheon+, DES-Dovekie, and DESY5), and Cosmic Chronometer data. We find that diffusion models systematically achieve lower best-fit $χ^{2}$ values than $Λ$CDM across all dataset combinations considered, indicating a modest but persistent improvement in goodness of fit. Nevertheless, the reduction in $χ^{2}$ is insufficient to offset the larger parameter space, leading standard information criteria to favor the simpler $Λ$CDM model. Despite this result, all dataset combinations consistently prefer a nonvanishing diffusion contribution corresponding to approximately $20\%$ of the present dark-energy budget, with a posterior probability $P(f_Q>0.05) =96.78\%$. From an observational perspective, diffusion models therefore remain a viable extension of the standard cosmological scenario and motivate the exploration of simpler diffusion parameterizations, particularly in light of upcoming high-precision cosmological surveys.
Comments12 pages, 4 figures. Comments are welcome
