Title: CMB Lensing Beyond the Power Spectrum: Cosmological Constraints from the One-Point PDF and Peak Counts Show Chinese title

Title: CMB透镜效应 beyond 功率谱：来自单点PDF和峰计数的宇宙学限制

Abstract: Unprecedentedly precise cosmic microwave background (CMB) data are expected from ongoing and near-future CMB Stage-III and IV surveys, which will yield reconstructed CMB lensing maps with effective resolution approaching several arcminutes. The small-scale CMB lensing fluctuations receive non-negligible contributions from nonlinear structure in the late-time density field. These fluctuations are not fully characterized by traditional two-point statistics, such as the power spectrum. Here, we use $N$-body ray-tracing simulations of CMB lensing maps to examine two higher-order statistics: the lensing convergence one-point probability distribution function (PDF) and peak counts. We show that these statistics contain significant information not captured by the two-point function, and provide specific forecasts for the ongoing Stage-III Advanced Atacama Cosmology Telescope (AdvACT) experiment. Considering only the temperature-based reconstruction estimator, we forecast 9$\sigma$ (PDF) and 6$\sigma$ (peaks) detections of these statistics with AdvACT. Our simulation pipeline fully accounts for the non-Gaussianity of the lensing reconstruction noise, which is significant and cannot be neglected. Combining the power spectrum, PDF, and peak counts for AdvACT will tighten cosmological constraints in the $\Omega_m$-$\sigma_8$ plane by $\approx 30\%$, compared to using the power spectrum alone. Show Chinese abstract

Abstract: 前所未有的精确宇宙微波背景（CMB）数据预计会来自于正在进行和即将到来的CMB第三阶段和第四阶段调查，这些调查将产生重建的CMB透镜化地图，其有效分辨率接近几弧分。 小尺度的CMB透镜化涨落受到晚期密度场中非线性结构的非可忽略贡献。 这些涨落不能完全由传统的两点统计量（如功率谱）来表征。 在这里，我们使用CMB透镜化地图的$N$体光线追踪模拟来检验两种高阶统计量：透镜化汇聚一维概率分布函数（PDF）和峰值计数。 我们表明，这些统计量包含了两点多点函数未能捕捉到的重要信息，并且为正在进行的第三阶段高级阿塔卡马宇宙学望远镜（AdvACT）实验提供了具体的预测。 仅考虑基于温度的重建估计器，我们预测AdvACT将检测到9个$\sigma$（PDF）和6个$\sigma$（峰值）。 我们的模拟流程全面考虑了透镜化重建噪声的非高斯性，这是显著的并且不能被忽略。 与单独使用功率谱相比，结合AdvACT的功率谱、PDF和峰值计数将在$\Omega_m$-$\sigma_8$平面上使宇宙学限制紧缩$\approx 30\%$。