标题： 透镜化CMB功率谱的遮罩星系外源偏差 显示英文标题

标题： Lensed CMB power spectrum biases from masking extragalactic sources

摘要： 宇宙微波背景（CMB）被大尺度结构引力透镜化，这会扭曲任何方向上原始各向异性的观测结果。 在天空上平均来看，这一重要效应通常通过透镜化CMB功率谱进行建模。 这考虑了这种畸变的方差，其中主要的方差效应是透镜偏移量的二次项。 然而，我们表明，如果在CMB图中遮蔽了与大尺度结构相关的明亮河外源，则使用标准伪$C_\ell$估计器在未遮蔽区域测量的功率谱会有一个额外的线性透镜效应，这是由遮蔽区域与透镜之间的相关性引起的。 这会导致未遮蔽观测点对之间未透镜距离的尺度依赖性平均去放大，并在 $\sim 10$ 弧分处对CMB相关函数产生一个负贡献。 我们给出了点源的简单解析模型，以及基于相关高斯前景场构建的阈值遮蔽。 我们通过现实的数值模拟验证了它们对于移除射电源和太阳-泽尔多维奇和宇宙红外背景峰值的遮蔽预测的一致性。 我们讨论了在没有遮蔽源的良好模型的情况下可用于测试该效应的简单诊断方法，并表明通过构建特定遮蔽可以观察到普朗克数据中的该效应。 对于用于普朗克和其他当前数据集分析的遮蔽，该效应可能可以忽略不计，但如果遮蔽了大量已解析源，则对于未来的调查可能会成为重要的亚百分比修正。 显示英文摘要

摘要： The cosmic microwave background (CMB) is gravitationally lensed by large-scale structure, which distorts observations of the primordial anisotropies in any given direction. Averaged over the sky, this important effect is routinely modelled with via the lensed CMB power spectra. This accounts for the variance of this distortion, where the leading variance effect is quadratic in the lensing deflections. However, we show that if bright extragalactic sources correlated with the large-scale structure are masked in a CMB map, the power spectrum measured over the unmasked area using a standard pseudo-$C_\ell$ estimator has an additional linear lensing effect arising from correlations between the masked area and the lensing. This induces a scale-dependent average demagnification of the unlensed distance between unmasked pairs of observed points and a negative contribution to the CMB correlation function peaking at $\sim 10$ arcmin. We give simple analytic models for point sources and a threshold mask constructed on a correlated Gaussian foreground field. We demonstrate the consistency of their predictions for masks removing radio sources and peaks of Sunyaev-Zeldovich and cosmic infrared background emissions using realistic numerical simulations. We discuss simple diagnostics that can be used to test for the effect in the absence of a good model for the masked sources and show that by constructing specific masks the effect can be observed on Planck data. For masks employed in the analysis of Planck and other current data sets, the effect is likely to be negligible, but may become an important sub-percent correction for future surveys if substantial populations of resolved sources are masked.