| Title: |
SwiftCℓ: fast differentiable angular power spectra beyond Limber |
| Authors: |
Reymond, Laura; Reeves, Alexander; Zhang, Pierre; id_orcid:0 000-0002-2866-7363; Refregier, Alexandre |
| Source: |
Journal of Cosmology and Astroparticle Physics, 2026 (1) |
| Publisher Information: |
IOP Publishing |
| Publication Year: |
2026 |
| Collection: |
ETH Zürich Research Collection |
| Subject Terms: |
power spectrum; redshift surveys; cosmological parameters from LSS; gravitational lensing |
| Description: |
The upcoming stage IV wide-field surveys will provide high precision measurements of the large-scale structure (LSS) of the universe. Their interpretation requires fast and accurate theoretical predictions including large scales. For this purpose, we introduce SwiftC & ell;, a fast, accurate and differentiable JAX-based pipeline for the computation of the angular power spectrum beyond the Limber approximation. It uses a new FFTLog-based method which can reach arbitrary precision and includes interpolation along k, allowing for kdependent growth factor and biases. SwiftC & ell; includes a wide range of probes and effects such as galaxy clustering, including magnification bias, redshift-space distortions and primordial non-Gaussianity, weak lensing, including intrinsic alignment, cosmic microwave background (CMB) lensing and CMB integrated Sachs-Wolfe effect. We compare our pipeline to the other available beyond-Limber codes within the N5K challenge from the Rubin Observatory Legacy Survey of Space and Time (LSST) Dark Energy Science Collaboration. SwiftC & ell; computes the 120 different angular power spectra over 103 & ell;-multipoles in 5 ms on one GPU core while the computation of the gradient is approximately 4x slower. Using a pre-calculation, SwiftC & ell; is thus about 40x faster than the winner of the N5K challenge with comparable accuracy. Furthermore, all outputs are auto-differentiable, facilitating gradient-based sampling and robust and accurate Fisher forecasts. We showcase a Markov Chain Monte Carlo, a Hamiltonian Monte Carlo and a Fisher forecast on an LSST-like survey, illustrating SwiftC & ell;'s differentiability, speed and reliability in measuring cosmological parameters. The code is publicly available at https://cosmo-gitlab.phys.ethz.ch/cosmo_public/swiftcl. ; ISSN:1475-7516 |
| Document Type: |
article in journal/newspaper |
| File Description: |
application/application/pdf |
| Language: |
English |
| Relation: |
info:eu-repo/semantics/altIdentifier/wos/001677487000002; https://hdl.handle.net/20.500.11850/795737 |
| DOI: |
10.3929/ethz-c-000795737 |
| Availability: |
https://hdl.handle.net/20.500.11850/795737; https://doi.org/10.3929/ethz-c-000795737 |
| Rights: |
info:eu-repo/semantics/openAccess ; http://creativecommons.org/licenses/by/4.0/ ; Creative Commons Attribution 4.0 International |
| Accession Number: |
edsbas.CE6A56E |
| Database: |
BASE |