下一代宇宙微波背景巡天对中微子及其他轻遗迹的灵敏度
Sensitivity of Next-Generation CMB Surveys to Neutrinos and Other Light Relics
AI总结：
本研究利用DRAFT工具对CMB-S4不同巡天配置的$N_\mathrm{eff}$测量灵敏度做Fisher矩阵预测，给出精度结果并探讨其对早期宇宙物理研究的意义。
AI中文摘要：
中微子及其他轻遗迹会在宇宙微波背景各向异性中留下特征印记，使其观测成为探测早期宇宙粒子组成与热历史的灵敏手段。这类相对论性物种的能量密度由其有效数$N_\mathrm{eff}$参数化。在百分比水平上测量该参数是CMB-S4及其他实验长期以来的科学目标，将能检验粒子物理标准模型内外一系列有充分理论依据的物理理论。本文中，我们针对CMB-S4广泛设计阶段考虑的多种巡天配置，给出了其对$N_\mathrm{eff}$预期灵敏度的Fisher矩阵预测。概念设计方案在七年观测周期内可达到$σ(N_\mathrm{eff}) < 0.03$，而修订后的配置需在更长时间尺度上才能达到相同精度。我们补充了相同多极矩范围内受宇宙方差限制的巡天结果，以量化通过额外仪器、观测和理论努力可获得的提升空间。最后，我们讨论了精确$N_\mathrm{eff}$测量对辐射扇区、大爆炸核合成、轻热遗迹及其他早期宇宙物理的广泛意义。本工作中的预测使用公开发布的DRAFT（暗辐射各向异性推演团队）工具完成。该工具提供了从模拟前景图、成分分离到去透镜化以及任意宇宙学参数预期灵敏度的端到端流程，可直接应用于其他宇宙微波背景巡天设计。
英文摘要：
Neutrinos and other light relics leave characteristic imprints in the cosmic microwave background anisotropies, making their observation a sensitive probe of the particle content and thermal history of the early universe. The energy density in these relativistic species is parameterized by their effective number $N_\mathrm{eff}$. Measuring this parameter at the percent level, which is a long-standing science goal of CMB-S4 and other experiments, would test a wide range of well-motivated physics within and beyond the Standard Model of particle physics. In this paper, we present Fisher-matrix forecasts of the projected sensitivity to $N_\mathrm{eff}$ of several CMB-S4 survey configurations considered during its extensive design phase. The conceptual design reaches $σ(N_\mathrm{eff}) < 0.03$ over its seven-year observing period, while the revised configuration achieves the same precision over a longer timescale. We complement these results with a cosmic-variance-limited survey over the same multipole range to quantify the room for improvement accessible with additional instrumental, observational, and theoretical efforts. Finally, we discuss the broad implications of precise $N_\mathrm{eff}$ measurements for the radiation sector, big bang nucleosynthesis, light thermal relics, and other early-universe physics. The forecasts presented in this work are performed with the publicly released DRAFT (Dark Radiation Anisotropy Flowdown Team) tool. It provides an end-to-end pipeline from simulated foreground maps and component separation to delensing and projected sensitivities for any cosmological parameter, and it can be directly applied to other cosmic microwave background survey designs.
