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

Title: CMB 弱引力透镜超越功率谱：来自一点概率分布函数和峰值计数的宇宙学约束

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 30$\sigma$ (PDF) and 10$\sigma$ (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）数据将来自正在进行的和近期的CMB第三阶段和第四阶段调查，这将产生有效分辨率接近几角分的重建CMB引力透镜图。 小尺度CMB引力透镜涨落从晚期密度场的非线性结构中获得不可忽略的贡献。 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$N$-体光线追踪模拟的CMB引力透镜图来检查两种高阶统计量：引力透镜会聚的一点概率分布函数（PDF）和峰值计数。 我们表明这些统计量包含两点函数未捕捉到的重要信息，并为正在进行的第三阶段先进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30$\sigma$（PDF）和10$\sigma$（峰值）这些统计量。 我们的模拟流程充分考虑了引力透镜重建噪声的非高斯性，这是显著且不能被忽略的。 将AdvACT的功率谱、PDF和峰值计数结合起来，相比于仅使用功率谱，将在$\Omega_m$-$\sigma_8$平面上收紧宇宙学约束$\approx 30\%$。