Cosmological Leverage from the Matter Power Spectrum in the Presence of Baryon and Nonlinear Effects

TL;DR

This paper demonstrates that incorporating smaller scales in galaxy clustering analyses, while accounting for complex nonlinear, bias, and baryonic effects, significantly enhances constraints on dark energy and neutrino mass.

Contribution

It introduces a model-independent approach to include high-wavenumber data in cosmological analyses, improving parameter constraints despite many nuisance parameters.

Findings

Increased maximum wavenumber improves dark energy constraints.

Breaking degeneracies beyond linear scales enhances parameter estimation.

Modeling uncertainties allows robust use of small-scale data.

Abstract

We investigate how the use of higher wavenumbers (smaller scales) in the galaxy clustering power spectrum influences cosmological constraints. We take into account uncertainties from nonlinear density fluctuations, (scale dependent) galaxy bias, and baryonic effects. Allowing for substantially model independent uncertainties through separate fit parameters in each wavenumber bin that also allow for the redshift evolution, we quantify strong gains in dark energy and neutrino mass leverage with increasing maximum wavenumber, despite marginalizing over numerous (up to 125) extra fit parameters. The leverage is due to not only an increased number of modes but, more significantly, breaking of degeneracies beyond the linear regime.