# How to add massive neutrinos to your $\Lambda$CDM simulation -- extending cosmology rescaling algorithms

## TL;DR

This paper extends cosmology-rescaling algorithms to include massive neutrinos, enabling fast and accurate predictions of large-scale structure in neutrino cosmologies based on standard $\\Lambda$CDM simulations.

## Contribution

The authors develop a method to modify existing $\\Lambda$CDM simulations to incorporate massive neutrinos, achieving high accuracy in matter power spectrum and halo mass function predictions.

## Key findings

- Matter power spectrum recovered within 1% for neutrino masses 0.06-0.3 eV.
- Halo mass function predicted within a few percent across a wide mass range.
- Galaxy correlation multipoles match simulations over relevant scales.

## Abstract

Providing accurate predictions for the spatial distribution of matter and luminous tracers in the presence of massive neutrinos is an important task, given the imminent arrival of highly accurate large-scale structure observations. In this work, we address this challenge by extending cosmology-rescaling algorithms to massive neutrino cosmologies. In this way, a $\Lambda$CDM simulation can be modified to provide nonlinear structure formation predictions in the presence a hot component of arbitrary mass, and, if desired, to include non-gravitational modifications to the clustering of matter on large scales. We test the accuracy of the method by comparing its predictions to a suite of simulations carried out explicitly including a neutrino component in its evolution equations. We find that, for neutrino masses in the range $M_\nu \in [0.06, 0.3] ~ \mathrm{eV}$ the matter power spectrum is recovered to better than $1\%$ on all scales $k<2~h~\mathrm{Mpc}^{-1}$. Similarly, the halo mass function is predicted at a few percent level over the range $M_{\rm halo} \in [10^{12}, 10^{15}] ~ h^{-1} ~ \mathrm{M}_{\odot}$, and so do also the multipoles of the galaxy 2-point correlation function in redshift space over $r \in [0.1, 200] ~ h^{-1} ~ \mathrm{Mpc}$. We provide parametric forms for the necessary transformations, as a function of $\Omega_{\rm m}$ and $\Omega_{\nu}$ for various target redshifts.