Suitable Initial Conditions for Newtonian Simulations with Massive Neutrinos

TL;DR

This paper introduces a new method using the Newtonian motion gauge framework to set initial conditions in cosmological simulations involving massive neutrinos, addressing limitations of traditional rescaling techniques.

Contribution

It proposes an alternative approach for initial conditions in simulations with massive neutrinos, overcoming the limitations of the standard rescaling method.

Findings

Traditional rescaling is not feasible with massive neutrinos.

The Newtonian motion gauge framework provides a viable alternative.

The method improves the accuracy of cosmological N-body simulations.

Abstract

Initial conditions for cosmological N-body simulations are usually calculated by rescaling the present day linear power spectrum obtained from an Einstein-Boltzmann solver to the initial time employing the scale-independent matter growth function. For the baseline Lambda-CDM model, this has been shown to be consistent with General Relativity (GR) even in the presence of relativistic species such as photons. We show that this approach is not feasible in cosmologies with massive neutrinos and present an alternative method employing the Newtonian motion gauge framework.