1998/05/13 by Arthur Kosowsky, Kosowsky, Arthur · 1 citation
Physics and Astronomy · #Astrophysics (astro-ph) #Astrophysics and Cosmic Phenomena #Cosmology and Gravitation Theories #FOS: Physical sciences #Radio Astronomy Observations and Technology #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9805173
9 pages with 4 included figures. C code available on request
arxiv created 1998/05/13 · openalex publication_date 1998/05/13 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Fast and accurate computations of the power spectrum of cosmic microwave background fluctuations are essential for comparing current and upcoming data sets with the large parameter space of viable cosmological models. The most efficient numerical algorithm for power spectrum calculation, recently implemented by Seljak and Zaldarriaga, involves integrating sources against spherical Bessel functions or, in the case of a non-flat universe, analogous hyperspherical Bessel functions. Evaluation of these special functions usually dominates the computation time in non-flat spatial geometries. This paper presents a highly accurate and very fast WKB approximation for computing hyperspherical Bessel functions which will greatly increase the speed of microwave background power spectrum computations in open and closed universes.