Fast CMB lensing using statistical interpolation on the sphere

Understand

We describe a accurate and fast pixel-based statistical method to interpolate fields of arbitrary spin on the sphere.

• We call this method Fast and Lean Interpolation on the Sphere (FLINTS).
• The method predicts the optimal interpolated values based on the theory of isotropic Gaussian random fields and provides an accurate error estimate at no additional cost.
• We use this method to compute lensed Cosmic Microwave Background (CMB) maps precisely and quickly, achieving a relative precision of 0.02% at a HEALPix resolution of Nside=4096, for a bandlimit of l_max=4096 in the same time it takes to simulate the original, unlensed CMB map.