发表机构
Indira Gandhi University; Gurugram University; GLA University（英迪拉·甘地大学; 古尔冈大学; GLA大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究在非平坦宇宙背景下用 DESI-DR2、BBN 和四组超新星数据约束 Hu-Sawicki $f(R)$ 引力，发现其可作为 $\Lambda$CDM 的统计可行替代，且曲率限制依赖于引力模型。
AI 中文摘要
晚期宇宙加速通常被归因于宇宙学常数，尽管 $\Lambda$CDM 模型仍面临若干理论困难，使得替代引力模型持续受到积极考虑。本研究在空间非平坦背景下考察 Hu-Sawicki $f(R)$ 模型，将修正引力参数 $b$ 和曲率密度 $\Omega_k$ 均作为自由参数，利用 DESI-DR2 BAO、BBN 以及四个 Ia 型超新星汇编——PantheonPlus、PantheonPlus+SH0ES、Union3 和 DESY5yr——进行约束。在所有四种组合中，$H_0$ 和 $\Omega_m$ 保持接近其 $\Lambda$CDM 值，仅在 SH0ES 校准的数据集中出现明显的 $H_0$ 偏移。参数 $b$ 在四次拟合中的三次以优于 $2\sigma$ 的显著性偏离零，其中 DESY5yr 最为显著，而仅 SH0ES 校准的组合偏好 $b<0$。$b$、$H_0$ 和 $\Omega_k$ 之间存在强正相关，这构成了该偏移的基础，表明一旦允许这种额外自由度，在 $\Lambda$CDM 下获得的曲率特征可以被重新吸收到修正引力部门中。通过 AIC 和 BIC 进行的统计模型比较给出了混合结果：AIC 在四种组合中的三种倾向于 Hu-Sawicki 模型，而 BIC 对额外参数的更重惩罚在大多数情况下偏向 $\Lambda$CDM，仅 DESY5yr 在两种准则下均被偏好。这些发现表明，具有不受约束曲率的 Hu-Sawicki $f(R)$ 情景尽管并非明显更优，但仍是 $\Lambda$CDM 的一个统计上可行的替代方案，并且 $\Lambda$CDM 内部产生的曲率限制不能被视为独立于底层引力模型。
英文摘要
Late-time cosmic acceleration is conventionally ascribed to a cosmological constant, though $Λ$CDM continues to face several theoretical difficulties that keep alternative gravity models under active consideration. This work examines the Hu-Sawicki $f(R)$ model in a spatially non-flat background, with the modified-gravity parameter $b$ and the curvature density $Ω_k$ both treated as free parameters, constrained using DESI-DR2 BAO, BBN, and four Type Ia supernova compilations -- PantheonPlus, PantheonPlus+SH0ES, Union3, and DESY5yr. Across all four combinations, $H_0$ and $Ω_m$ stay close to their $Λ$CDM values, with a noticeable shift in $H_0$ appearing only for the SH0ES-calibrated dataset. The parameter $b$ departs from zero at better than $2σ$ in three of the four fits, most prominently for DESY5yr, whereas the SH0ES-calibrated combination alone prefers $b<0$. A strong positive correlation among $b$, $H_0$, and $Ω_k$ underlies this shift, suggesting that curvature signatures obtained under $Λ$CDM can be reabsorbed into the modified-gravity sector once this additional freedom is allowed. Statistical model comparison via AIC and BIC gives a mixed picture: AIC leans toward the Hu-Sawicki model in three of the four combinations, while BIC's heavier penalty on the extra parameter favors $Λ$CDM in most cases, and only DESY5yr is preferred under both criteria. These findings show that the Hu-Sawicki $f(R)$ scenario with unconstrained curvature is nonetheless a statistically feasible, if not obviously preferred, alternative to $Λ$CDM, and that curvature restrictions generated inside $Λ$CDM cannot be viewed as independent of the underlying gravity model.
Comments16 pages, 11 figures, 2 tables
