Suitable initial conditions for Newtonian simulations with massive neutrinos

Initial conditions for cosmological N-body simulations are usually calculated by resealing 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 ACDM 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 becomes significantly more complex in cosmologies with massive neutrinos and present an alternative method based on the Newtonian motion gauge framework.