Effect of lensing non-Gaussianity on the CMB power spectra
Effect of lensing non-Gaussianity on the CMB power spectra
复制标题
透镜非高斯性对 CMB 功率谱的影响
DOI：
10.1088/1475-7516/2016/12/003
复制
发表时间：
2016
影响因子：
6.4
通讯作者：
G. Pratten
中科院分区：
文献类型：
--
作者：
A. Lewis;G. Pratten
观测到的CMB各向异性是透镜化的，并且假设透镜化偏转是高斯的，可以精确地计算透镜化功率谱。然而，由于非线性大尺度结构生长和后玻恩校正，透镜偏转实际上是稍微非高斯的。我们计算了由透镜双谱决定的非高斯性对透镜CMB功率谱的超前修正。假设没有原始的非高斯性，最低阶结果给出了小尺度上的BB和EE偏振谱的约0.3%的修正。然而，我们表明，EE上的影响减少了约一个因素的两个高阶高斯透镜平滑，使总的影响可以忽略不计，在可预见的未来。我们给出了一个简单的分析模型的预期从大规模的透镜场的偏斜的信号，效果是类似于一个净缩小，因此在声学尺度的小的变化（因此与占主导地位的透镜平滑，主要影响功率谱的波峰和波谷的相位）。
Observed CMB anisotropies are lensed, and the lensed power spectra can be calculated accurately assuming the lensing deflections are Gaussian. However, the lensing deflections are actually slightly non-Gaussian due to both non-linear large-scale structure growth and post-Born corrections. We calculate the leading correction to the lensed CMB power spectra from the non-Gaussianity, which is determined by the lensing bispectrum. Assuming no primordial non-Gaussianity, the lowest-order result gives ∼ 0.3% corrections to the BB and EE polarization spectra on small-scales. However we show that the effect on EE is reduced by about a factor of two by higher-order Gaussian lensing smoothing, rendering the total effect safely negligible for the foreseeable future. We give a simple analytic model for the signal expected from skewness of the large-scale lensing field; the effect is similar to a net demagnification and hence a small change in acoustic scale (and therefore out of phase with the dominant lensing smoothing that predominantly affects the peaks and troughs of the power spectrum).