Galaxy Skew-Spectra in Redshift-Space

TL;DR

This paper introduces galaxy skew-spectra in redshift-space as a simple, effective method to analyze higher-order correlations in galaxy surveys, capturing the bispectrum contributions with ease and accuracy.

Contribution

The paper demonstrates that skew-spectra can efficiently capture all tree-level bispectrum contributions in redshift-space galaxy data, simplifying higher-order analysis.

Findings

Skew-spectra accurately match analytical predictions.

Method effectively captures bispectrum contributions.

Pipeline shows expected dependence on bias and growth rate.

Abstract

Modern galaxy surveys focus on the galaxy power spectrum or 2-point correlation function to test and constrain cosmological models. Additional information comes from higher-order N-point functions, but their analysis is challenging. A simple solution is to compute the cross-power spectrum between the squared galaxy density and the galaxy density. Being simple to measure and to plot, this skew-spectrum shares many of the familiar useful properties of the standard galaxy power spectrum. We show that by computing multiple quadratic fields and correlating them with the density, all contributions to the tree-level redshift-space galaxy bispectrum can be captured with skew-spectra. Using synthetic datasets, we show that our measurement pipeline matches analytical predictions, and that their dependence on galaxy bias parameters and the logarithmic growth rate is as expected theoretically.