Fast Theoretical Predictions for Spherical Fourier Analysis of Large-Scale Structures

TL;DR

This paper introduces a fast computational method for spherical Fourier analysis of large-scale structures, enabling efficient predictions of cosmological constraints from upcoming galaxy surveys.

Contribution

The authors develop a rapid code for SFB power spectrum calculation that accounts for survey geometry and physical effects, improving analysis efficiency.

Findings

The code significantly speeds up SFB power spectrum computations.

Line of sight effects and non-Gaussianity impact the SFB power spectrum estimates.

Predicted cosmological constraints are tighter with realistic survey specifications.

Abstract

On-going or soon to come cosmological large-scale structure surveys such as DESI, SPHEREx, Euclid, or the High-Latitude Spectroscopic Survey of the Nancy Grace Roman Space Telescope promise unprecedented measurement of the clustering of galaxies on large scales. When quantified with the Cartesian Fourier basis, the measurement of these large scales requires the introduction of so-called wide-angle corrections. By contrast, the measurement of the power spectrum in a spherical Fourier Bessel (SFB) basis does not require such corrections and naturally accounts for the spherical survey geometries. Here, we develop and implement a fast code to construct the SFB power spectrum and investigate how line of sight effects, physics such as non-Gaussianity, and differing survey geometries affect SFB power spectrum estimates. We then leverage our program to predict the tightness of cosmological constraints from realistic survey specifications using a Fisher matrix formalism.