AI 中文总结
该研究利用ACT DR6 CMB数据，对各向异性屏蔽和宇宙双折射效应进行分析，未显著探测到两种效应，给出相关上限约束，为下一代地面CMB巡天的相关研究铺路。
AI 中文摘要
尽管我们已从近期的毫米波巡天中获取了大量关于宇宙微波背景（CMB）的信息，但CMB的诸多次级各向异性仍有待深入探索。本文聚焦其中两种效应：一是CMB光子与自由电子发生汤姆孙散射所诱导的各向异性屏蔽，二是宇宙双折射，即超出标准模型的宇称破缺物理导致的CMB偏振旋转。为测量这些效应，我们采用针对统计各向异性的最先进估计量，应用于阿塔卡马宇宙学望远镜（ACT）第6批数据（DR6）的CMB数据，构建了两种效应的噪声图和功率谱。对于各向异性屏蔽，我们在基线数据中未发现显著探测结果，对其功率谱设定的上限比当前再电离模型的预测值高两个数量级；在其中一个频率上，我们获得了与河外模拟预期一致的前景污染证据。对于各向异性双折射分析，我们同样未探测到信号，设定的信号上限与此前分析结果一致；相应地，我们得到陈-西蒙斯耦合项的上限为$g_{a \bar{\text{}}} < 4.9 \times 10^{-2} / H_\text{I}$，其中$H_\text{I}$为暴胀哈勃尺度。这些分析为下一代地面CMB巡天获取更严格约束奠定了基础。
英文摘要
While we have learned much from recent surveys of the mm-wave sky, many secondary anisotropies of the CMB remain under-explored. We consider two of these here: the anisotropic screening induced by Thomson scattering of CMB photons off free electrons, and cosmic birefringence, the rotation of CMB polarization due to parity-violating physics beyond the standard model. To measure these effects, we apply state-of-the-art estimators for statistical anisotropy to the ACT Data Release 6 CMB data and construct noisy maps and power spectra of both effects. For anisotropic screening, we find no significant detection with the baseline data, and place an upper limit on its power spectrum that is two orders of magnitude above predictions from current reionization models. We obtain evidence for some foreground contamination at one of our frequencies that is consistent with expectations from extragalactic simulations. For our anisotropic birefringence analysis, we also find no detection and place an upper limit on the signal that is consistent with previous analyses. We report a corresponding upper limit on the Chern-Simons coupling term $g_{a γ} < 4.9 \times 10^{-2} / H_\mathrm{I}$, with $H_\mathrm{I}$ the inflationary Hubble scale. These analyses pave the way toward obtaining improved constraints with the next generation of ground-based CMB surveys.
Comments31 pages, 24 figures. To be submitted to ApJ
