Issue |
A&A
Volume 678, October 2023
|
|
---|---|---|
Article Number | A165 | |
Number of page(s) | 8 | |
Section | Numerical methods and codes | |
DOI | https://doi.org/10.1051/0004-6361/202346717 | |
Published online | 20 October 2023 |
Improved cosmic microwave background (de-)lensing using general spherical harmonic transforms
1
Max-Planck Institut für Astrophysik,
Karl-Schwarzschild-Str. 1,
85748
Garching,
Germany
2
Université de Genève, Département de Physique Théorique et CAP,
24 Quai Ansermet,
1211
Genève 4,
Switzerland
e-mail: sebastian.belkner@unige.ch
Received:
20
April
2023
Accepted:
28
July
2023
Deep cosmic microwave background polarization experiments allow a very precise internal reconstruction of the gravitational lensing signal in principle. For this aim, likelihood-based or Bayesian methods are typically necessary, where very large numbers of lensing and delensing remappings on the sphere are sometimes required before satisfactory convergence. We discuss here an optimized piece of numerical code in some detail that is able to efficiently perform both the lensing operation and its adjoint (closely related to delensing) to arbitrary accuracy, using nonuniform fast Fourier transform technology. Where applicable, we find that the code outperforms current widespread software by a very wide margin. It is able to produce high-resolution maps that are accurate enough for next-generation cosmic microwave background experiments on the timescale of seconds on a modern laptop. The adjoint operation performs similarly well and removes the need for the computation of inverse deflection fields. This publicly available code enables de facto efficient spherical harmonic transforms on completely arbitrary grids, and it might be applied in other areas as well.
Key words: cosmic background radiation
© The Authors 2023
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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