Redshift-space distortions in massive neutrino and evolving dark energy cosmologies

TL;DR

This paper extends the Time-RG perturbative framework to accurately compute the redshift-space power spectrum in cosmologies with massive neutrinos and evolving dark energy, enabling precise tests of cosmological models.

Contribution

The authors develop a scale-dependent perturbation theory extension for redshift space, incorporating massive neutrinos and dynamic dark energy, validated against N-body simulations.

Findings

Time-RG predicts the monopole and quadrupole to 1% accuracy up to specified scales.

The method distinguishes effects of neutrino mass and dark energy evolution on power spectrum.

The approach remains accurate even for neutrino masses above current bounds and rapid dark energy evolution.

Abstract

Large-scale structure surveys in the coming years will measure the redshift-space power spectrum to unprecedented accuracy, allowing for powerful new tests of the LambdaCDM picture as well as measurements of particle physics parameters such as the neutrino masses. We extend the Time-RG perturbative framework to redshift space, computing the power spectrum P_s(k,mu) in massive neutrino cosmologies with time-dependent dark energy equations of state w(z). Time-RG is uniquely capable of incorporating scale-dependent growth into the P_s(k,mu) computation, which is important for massive neutrinos as well as modified gravity models. Although changes to w(z) and the neutrino mass fraction both affect the late-time scale-dependence of the non-linear power spectrum, we find that the two effects depend differently on the line-of-sight angle mu. Finally, we use the HACC N-body code to quantify errors in the perturbative calculations. For a LambdaCDM model at redshift z=1, our procedure predicts the monopole~(quadrupole) to 1% accuracy up to a wave number 0.19h/Mpc (0.28h/Mpc), compared to 0.08h/Mpc (0.07h/Mpc) for the Kaiser approximation and 0.19h/Mpc (0.16h/Mpc) for the current state-of-the-art perturbation scheme. Our calculation agrees with the simulated redshift-space power spectrum even for neutrino masses above the current bound, and for rapidly-evolving dark energy equations of state, |dw/dz| ~ 1. Along with this article, we make our redshift-space Time-RG implementation publicly available as the code redTime.