Lensing simulations by Taylor expansion -- not so inefficient after all

Abstract

Cosmic Microwave Background lensing simulation by Taylor expansion has long been considered impractical due to slow convergence, but a recent flat-sky implementation shows that a simple trick eliminates this problem, making Taylor lensing a fast and simple lensing algorithm for the flat sky. Here we generalize the method to the full sky, and study its convergence and performance relative to a commonly used numerical code, Lenspix, with extensive benchmarks of both. Compared to the flat sky case, the method takes a speed hit due to the slow speed of spherical harmonic transforms compared to fast Fourier transforms, resulting in speeds of 1/3 to 2/3 of Lenspix for similar accuracy.

7 pages, 6 figures, submitted to JCAP

References in corpus (6)

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• Correlation of CMB with large-scale structure: II. Weak lensing
• Cosmological Information from Lensed CMB Power Spectra
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• The Simons Observatory: Galactic Science Goals and Forecasts
• MillimeterDL: Deep Learning Simulations of the Microwave Sky
• Comparison of delensing methodologies and assessment of the delensing capabilities of future experiments
• Searching for patchy reionization from cosmic microwave background with hybrid quadratic estimators
• Spin characterisation of systematics in CMB surveys -- a comprehensive formalism
• Accelerating Cosmic Microwave Background map-making procedure through preconditioning
• Detecting Electron Density Fluctuations from Cosmic Microwave Background Polarization using a Bispectrum Approach
• The C-Band All-Sky Survey (C-BASS): Total intensity point-source detection over the northern sky
• Fast map-based simulations of systematics in CMB surveys including effects of the scanning strategy