FASTPT: a novel algorithm to calculate convolution integrals in cosmological perturbation theory
Abstract
We present a novel algorithm, FASTPT, for performing convolution or modecoupling integrals that appear in nonlinear cosmological perturbation theory. The algorithm uses several properties of gravitational structure formation—the locality of the dark matter equations and the scale invariance of the problem—as well as Fast Fourier Transforms to describe the input power spectrum as a superposition of power laws. This yields extremely fast performance, enabling modecoupling integral computations fast enough to embed in Monte Carlo Markov Chain parameter estimation. We describe the algorithm and demonstrate its application to calculating nonlinear corrections to the matter power spectrum, including oneloop standard perturbation theory and the renormalization group approach. We also describe our public code (in Python) to implement this algorithm. The code, along with a user manual and example implementations, is available at https://github.com/JoeMcEwen/FASTPT.
 Publication:

Journal of Cosmology and Astroparticle Physics
 Pub Date:
 September 2016
 DOI:
 10.1088/14757516/2016/09/015
 arXiv:
 arXiv:1603.04826
 Bibcode:
 2016JCAP...09..015M
 Keywords:

 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 24 pages, 5 figures, 2 tables. fig.1 corrected. changes made. matched with the journal version. Code available at https://github.com/JoeMcEwen/FASTPT