AI 中文总结
本研究用高斯过程回归重建哈勃参数，发现核光滑性层级会导致H₀等结果的系统单调趋势，该结果稳健且可通过导数差异解释，为非参数宇宙学推断中核的选择提供依据。
AI 中文摘要
我们利用高斯过程回归开展模型无关的宇宙膨胀历史重建，探究协方差核的光滑性属性如何影响推断出的哈勃参数。利用32个宇宙计时器测量值，我们用Matérn 3/2、5/2、7/2、9/2核以及平方指数核重建H(z)，这些核构成了定义明确的可微性层级。在该层级中，我们观察到系统且单调的趋势：核光滑性提升与重建的现今哈勃常数H₀逐渐降低相关，同时统计不确定性减小。该行为并非表明对特定核的统计偏好，而是反映非参数重建对协方差函数编码的假设光滑性先验的敏感性。相同排序体现在描述性拟合优度统计量中，且在纳入最新DESI DR2 BAO测量值并进行刀切重抽样测试时保持稳定，证明其对单个数据点及数据集变化具有稳健性。对导数重建的额外分析显示，核可微性的差异会传播到膨胀历史的局部斜率中，为观测到的H₀排序提供一致解释。我们的结果强调，核光滑性在高斯过程重建中发挥重要作用，在解释非参数宇宙学推断时应仔细考量。
英文摘要
We perform a model independent reconstruction of the cosmic expansion history using Gaussian Process regression, investigating how the smoothness properties of covariance kernels influence the inferred Hubble parameter. Using 32 cosmic chronometer measurements, we reconstruct $H(z)$ with the Matérn $3/2$, $5/2$, $7/2$, $9/2$, and Squared Exponential kernels, which form a well-defined hierarchy of differentiability. Across this hierarchy, we observe a systematic and monotonic trend in which increasing kernel smoothness is associated with progressively lower reconstructed values of the present-day Hubble constant $H_0$, accompanied by reduced statistical uncertainties. Rather than indicating a statistical preference for a specific kernel, this behaviour reflects the sensitivity of non-parametric reconstructions to the assumed smoothness prior encoded in the covariance function. The same ordering is reflected in descriptive goodness-of-fit statistics and remains stable when incorporating recent DESI DR2 BAO measurements and performing jackknife resampling tests, demonstrating robustness against individual data points and dataset variations. Additional analysis of derivative reconstructions shows that differences in kernel differentiability propagate into the local slope of the expansion history, providing a consistent interpretation of the observed ordering in $H_0$. Our results highlight that kernel smoothness plays an important role in Gaussian Process reconstructions and should be carefully accounted for when interpreting non-parametric cosmological inferences.
CommentsPublished in Physics Letters B
Journal refPhysics Letters B 877 (2026) 140456
DOI：10.1016/j.physletb.2026.140456
