宇宙加速的动力学测试：宇宙微波背景与宇宙红外背景的k近邻交叉相关性
Dynamical Test of Cosmic Acceleration: $k$-nearest Neighbor Cross Correlation of Cosmic Microwave Background and Cosmic Infrared Background
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中文总结 AI 辅助
研究宇宙加速的物理起源，通过测量宇宙微波背景与宇宙红外背景的k近邻交叉相关性进行动力学测试，发现正相关证据，量化幅度，该分析比两点相关函数提高检测显著性，还探索演化暗能量，结果与ΛCDM一致。
中文摘要 AI 辅助
宇宙加速的物理起源仍是现代宇宙学的核心问题之一。由引力势演化产生的积分萨克斯-沃尔夫（ISW）和里斯-夏马（RS）效应提供了宇宙加速的动力学测试。我们使用k近邻累积分布函数（kNN-CDF）测量了宇宙微波背景（CMB）的普朗克温度图与蒋义宽（2023年）的无前景100μm宇宙红外背景（CIB）图之间的交叉相关性。由于CIB图是从约6亿个延伸至z≈2.5的广域红外巡天探测器星系重建而来，该测量等同于星系-CMB交叉相关性。我们发现了正交叉相关性的证据，使用χ²检验在p = 0.02（2.3σ）时拒绝了无相关性的零假设。我们进一步用相对于假设宇宙学模型定义的AkNN量化其幅度，相对于包括ISW和RS效应的ΛCDM模拟数据，得到AkNN = 0.95±0.20（4.8σ）。kNN-CDF分析比两点相关函数将检测显著性提高了约20%。我们还通过从完整的CIB图构建两个层析图来探索演化的暗能量；结果与ΛCDM一致。例如，对CIB进行更精细的层析重建，如来自SPHEREx多波段数据，将进一步收紧对演化暗能量的约束。
英文摘要
The physical origin of cosmic acceleration remains one of the central questions in modern cosmology. The integrated Sachs-Wolfe (ISW) and Rees-Sciama (RS) effects, which arise from the evolution of gravitational potentials, provide a dynamical test of cosmic acceleration. We measure the cross correlation between the Planck temperature map of the cosmic microwave background (CMB) and a foreground-free map of the $100\,μ\mathrm{m}$ cosmic infrared background (CIB) from Y.-K. Chiang (2023), using the $k$-nearest neighbor cumulative distribution function ($k$NN-CDF). As the CIB map is reconstructed from ${\sim}600$ million Wide-field Infrared Survey Explorer galaxies extending to $z\approx2.5$, the measurement is equivalent to a galaxy-CMB cross correlation. We find evidence for a positive cross correlation, rejecting the null hypothesis of no correlation at $p=0.02~(2.3σ)$ using the $χ^2$ test. We further quantify its amplitude with $A_{k\mathrm{NN}}$, defined relative to an assumed cosmological model, and obtain $A_{k\mathrm{NN}}=0.95\pm0.20~(4.8σ)$ with respect to $Λ\mathrm{CDM}$ mock data including the ISW and RS effects. The $k$NN-CDF analysis improves the detection significance by ${\sim}20\%$ over the two-point correlation function. We also explore evolving dark energy by constructing two tomographic maps from the full CIB map; the results are consistent with $Λ$CDM. Finer tomographic reconstruction of the CIB, for example from multiband data of SPHEREx, would further tighten constraints on evolving dark energy.
