Impact of post-Born lensing on the CMB
Impact of post-Born lensing on the CMB
复制标题
出生后透镜效应对 CMB 的影响
DOI：
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复制
发表时间：
2016
期刊：
影响因子：
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通讯作者：
A. Lewis
中科院分区：
文献类型：
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作者：
G. Pratten;A. Lewis
CMB的透镜效应受到后玻恩透镜效应的影响，产生对会聚功率谱的修正并引入场旋转。数值计算表明，在可达尺度上，透镜会聚功率谱的影响在~ 0.2%的水平上，对于角分束和噪声水平~ 1 μK角分的观测，这种校正和场旋转是可以忽略的。场旋转产生了总透镜B模偏振振幅的2.5%（小尺度上的功率为0.2%），但在大尺度上具有蓝色光谱，使其在尺度上高度次显性于会聚B模，它们是原始引力波信号的混淆源。由于后玻恩信号是非线性的，它也产生一个双谱的收敛。我们发现，出生后的贡献的双谱大幅改变的形状预测从大规模的结构非线性单独，因此必须包括估计预期的总信号和双谱偏差的影响CMB透镜重建二次估计和其他可观的。场旋转功率谱只有在噪声水平为<$1 μK arcmin时才有可能被探测到，但它的收敛双谱在<$3 σ时可以用IV级观测观测到。旋转引起的和收敛引起的B模式是轻微相关的双谱，和双谱也产生额外的贡献，透镜BB功率谱。
Lensing of the CMB is affected by post-Born lensing, producing corrections to the convergence power spectrum and introducing field rotation. We show numerically that the lensing convergence power spectrum is affected at the ≲ 0.2% level on accessible scales, and that this correction and the field rotation are negligible for observations with arcminute beam and noise levels ≳ 1 μK arcmin. The field rotation generates ∼ 2.5% of the total lensing B-mode polarization amplitude (0.2% in power on small scales), but has a blue spectrum on large scales, making it highly subdominant to the convergence B modes on scales where they are a source of confusion for the signal from primordial gravitational waves. Since the post-Born signal is non-linear, it also generates a bispectrum with the convergence. We show that the post-Born contributions to the bispectrum substantially change the shape predicted from large-scale structure non-linearities alone, and hence must be included to estimate the expected total signal and impact of bispectrum biases on CMB lensing reconstruction quadratic estimators and other observables. The field-rotation power spectrum only becomes potentially detectable for noise levels ≪ 1 μK arcmin, but its bispectrum with the convergence may be observable at ∼ 3σ with Stage IV observations. Rotation-induced and convergence-induced B modes are slightly correlated by the bispectrum, and the bispectrum also produces additional contributions to the lensed BB power spectrum.
影响因子：
6.5
作者：
S. Hilbert;J. Hartlap;S. White;P. Schneider
通讯作者：
S. Hilbert;J. Hartlap;S. White;P. Schneider