Redshift-space distortion from dynamical dark energy with time-dependent Lagrangian perturbation theory

TL;DR

This paper models the impact of dynamical dark energy on redshift-space distortions using advanced Lagrangian perturbation theory, providing improved constraints for upcoming galaxy surveys and highlighting the importance of time-dependent growth functions.

Contribution

It introduces a second and third order Lagrangian perturbation theory with time-dependent growth functions to better model dark energy effects on redshift-space distortions.

Findings

Potentially improves density parameter constraints to better than 1%.

Constraints on $w_0$ and $w_a$ could be better than 5% and 60%.

Time-dependent growth functions can alter the nonlinear power spectrum by up to 10%.

Abstract

We apply the Lagrangian perturbation theory with time-dependent growth functions at second and third order of perturbation with the aim to model the effect of dynamical dark energy on redshift-space distortions. Our fiducial galaxy redshift surveys are modeled after the upcoming SKA and DESI redshift surveys. We include PLANCK CMB priors and the 20\% uncertainty on the linear bias parameter, incorporating the unknown instrumentation noise. After the marginalizing, our results show that the constraints on the density parameter could potentially get better than $\sim$1\%, while the constraints on $w_0$ and $w_{\rm a}$ could be better than $\sim 5\%$ and $\sim 60\%$ respectively, consistent with works done before. However, the inclusion of time-dependent growth functions would alter the nonlinear power spectrum by as much as $\sim$10\%. The inclusion of the time-dependent growth functions become crucial as the precision gets better.