AI 中文总结
该研究利用4066个FRB事件，结合Landy-Szalay估计量等，发现FRB天空的表观各向异性源于巡天选择函数，校正后其分布符合统计各向同性，验证了标准模型的相关预测。
AI 中文摘要
我们利用快速射电暴（FRB）的天空分布对宇宙的统计各向同性进行检验，所使用的样本来自多个巡天项目探测到的共4066个FRB事件。我们的方法基于Landy-Szalay估计量中的两点角相关函数w(θ)，结合层析绝对各向异性统计量，并通过互补的刀切法（jackknife）和自助法（bootstrap）重采样估计其观测不确定性。我们将两种估计量与各向同性模拟星表的分层集合进行对比，该集合传播了经验重建的巡天选择函数的不确定性，以及各向同性实现的泊松涨落。显著性通过协方差感知、SVD正则化的χ²统计量获得，该统计量通过模拟集合进行经验校准，我们评估了四个嵌套场景，逐步加入银道面掩膜和巡天选择函数。结果显示，原始FRB天空与各向同性存在显著不一致；仅银道面掩膜使这种张力降低约3倍，而选择函数使张力降低近四个数量级，表明表观各向异性由贡献巡天的极不均匀天空覆盖驱动，其中CHIME占主导。仅当结合两种效应时，我们发现观测分布与统计各向同性完全一致。该结果得到绝对各向异性估计量的独立验证，且在分析参数变化时稳定。因此，我们发现FRB天空分布与统计各向同性一致，有助于确认标准模型情景的主要预测之一。
英文摘要
We perform a test of statistical isotropy in the Universe using the sky distribution of fast radio bursts (FRBs), based on a compilation of $4066$ events detected by multiple surveys. Our method is based on the two-point angular correlation function $w(θ)$ as in the Landy--Szalay estimator, together with a tomographic absolute-anisotropy statistic, and estimates their observational uncertainties from complementary jackknife and bootstrap resampling. Both estimators are confronted with hierarchical ensembles of isotropic mock catalogs that propagate the uncertainties of empirically reconstructed survey selection functions, as well as the Poisson fluctuations of the isotropic realizations. The significances are obtained from a covariance-aware, SVD-regularized $χ^2$ statistic calibrated empirically against the mock ensemble, and we evaluate four nested scenarios that progressively incorporate a Galactic-plane mask and the survey selection functions. As for our results, we find that the raw FRB sky is strongly inconsistent with isotropy; Galactic masking alone reduces the tension by only a factor of $\sim 3$, whereas the selection functions reduce it by nearly four orders of magnitude, showing that the apparent anisotropy is driven by the highly non-uniform sky coverage of the contributing surveys, overwhelmingly dominated by CHIME. Only when both effects are combined we obtain that the observed distribution is fully consistent with statistical isotropy. This result is independently corroborated by the absolute-anisotropy estimator, and is stable under variations of the analysis parameters. Therefore, we find that the FRB sky distribution is consistent with statistical isotropy, helping confirm one of the main predictions of the standard model scenario.
Comments26 pages with 14 figures
