Extracting high-order cosmological information in galaxy surveys with power spectra

TL;DR

This paper demonstrates that analyzing both pre- and post-reconstruction galaxy power spectra allows for efficient extraction of higher-order cosmological information, improving constraints on dark energy models.

Contribution

It introduces a joint analysis method of power spectra from reconstructed galaxy samples to access higher-order information beyond the 2-point spectrum.

Findings

Joint analysis yields increased information over single-sample analysis.

Higher-order information enhances constraints on cosmological parameters.

Method simplifies use of higher-order data in galaxy surveys.

Abstract

The reconstruction method was proposed more than a decade ago to boost the signal of baryonic acoustic oscillations measured in galaxy redshift surveys, which is one of key probes for dark energy. After moving the observed overdensities in galaxy surveys back to their initial position, the reconstructed density field is closer to a linear Gaussian field, with higher-order information moved back into the power spectrum. We find that by jointly analysing power spectra measured from the pre- and post-reconstructed galaxy samples, higher-order information beyond the $2$-point power spectrum can be efficiently extracted, which generally yields an information gain upon the analysis using the pre- or post-reconstructed galaxy sample alone. This opens a window to easily use higher-order information when constraining cosmological models.