Rejuvenating Power Spectra II: the Gaussianized galaxy density field

TL;DR

This paper demonstrates that Gaussianizing transforms can significantly reduce nonlinearities and enhance the linearity and Fisher information of galaxy density power spectra, even with shot noise, across various resolutions and spaces.

Contribution

It introduces and evaluates the effectiveness of Gaussianizing transforms in improving power spectrum analysis of galaxy density fields, accounting for shot noise and resolution effects.

Findings

Gaussianization reduces nonlinearities in power spectra.

It increases the Fisher information content.

Gains vary with space type and grid resolution.

Abstract

We find that, even in the presence of discreteness noise, a Gaussianizing transform (producing a more-Gaussian one-point distribution) reduces nonlinearities in the power spectra of cosmological matter and galaxy density fields, in many cases drastically. Although Gaussianization does increase the effective shot noise, it also increases the power spectrum's fidelity to the linear power spectrum on scales where the shot noise is negligible. Gaussianizing also increases the Fisher information in the power spectrum in all cases and resolutions, although the gains are smaller in redshift space than in real space. We also find that the gain in cumulative Fisher information from Gaussianizing peaks at a particular grid resolution that depends on the sampling level.