Fast and accurate computation of projected two-point functions

Henry S. Grasshorn Gebhardt and Donghui Jeong
Phys. Rev. D 97, 023504 – Published 8 January 2018

Abstract

We present the two-point function from the fast and accurate spherical Bessel transformation (2-FAST) algorithm for a fast and accurate computation of integrals involving one or two spherical Bessel functions. These types of integrals occur when projecting the galaxy power spectrum P(k) onto the configuration space, ξν(r), or spherical harmonic space, C(χ,χ). First, we employ the FFTLog transformation of the power spectrum to divide the calculation into P(k)-dependent coefficients and P(k)-independent integrations of basis functions multiplied by spherical Bessel functions. We find analytical expressions for the latter integrals in terms of special functions, for which recursion provides a fast and accurate evaluation. The algorithm, therefore, circumvents direct integration of highly oscillating spherical Bessel functions.

Our code is available at https://github.com/hsgg/twoFAST.

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  • Received 15 September 2017

DOI:https://doi.org/10.1103/PhysRevD.97.023504

© 2018 American Physical Society

Physics Subject Headings (PhySH)

Gravitation, Cosmology & AstrophysicsInterdisciplinary PhysicsGeneral Physics

Authors & Affiliations

Henry S. Grasshorn Gebhardt* and Donghui Jeong

  • Department of Astronomy and Astrophysics, and Institute for Gravitation and the Cosmos, The Pennsylvania State University, University Park, Pennsylvania 16802, USA

  • *hsg113@psu.edu

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Issue

Vol. 97, Iss. 2 — 15 January 2018

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