The halo model in a massive neutrino cosmology

TL;DR

This paper develops and tests a halo model for massive neutrino cosmologies, accurately modeling non-linear matter clustering and neutrino effects, and compares it with N-body simulations up to scales of k=10 h/Mpc.

Contribution

The paper introduces a neutrino halo model that accurately predicts non-linear matter and neutrino clustering, extending the halo model framework to massive neutrino cosmologies.

Findings

Achieves ~20% accuracy in non-linear matter power spectra up to k=10 h/Mpc.

Matches N-body simulation results within 8% for scales below 0.2 h/Mpc for neutrino masses <0.3 eV.

Predicts neutrino and CDM-neutrino cross-power spectra with ~30% accuracy up to k=1 h/Mpc.

Abstract

We provide a quantitative analysis of the halo model in the context of massive neutrino cosmologies. We discuss all the ingredients necessary to model the non-linear matter and cold dark matter power spectra and compare with the results of N-body simulations that incorporate massive neutrinos. Our neutrino halo model is able to capture the non-linear behavior of matter clustering with a $\sim 20\%$ accuracy up to very non-linear scales of $k=10~h/$Mpc (which would be affected by baryon physics). The largest discrepancies arise in the range $k=0.5-1~h/$Mpc where the 1-halo and 2-halo terms are comparable and are present also in a massless neutrino cosmology. However, at scales $k<0.2~h/$Mpc our neutrino halo model agrees with the results of N-body simulations at the level of 8\% for total neutrino masses of $<0.3$ eV. We also model the neutrino non-linear density field as a sum of a linear and clustered component and predict the neutrino power spectrum and the cold dark matter-neutrino cross-power spectrum up to $k=1~h/$Mpc with $\sim$ 30\% accuracy. For masses below 0.15 eV the neutrino halo model captures the neutrino induced suppression, casted in terms of matter power ratios between massive and massless scenarios, with a 2\% agreement with the results of N-body/neutrino simulations. Finally, we provide a simple application of the halo model: the computation of the clustering of galaxies, in massless and massive neutrinos cosmologies, using a simple Halo Occupation Distribution scheme and our halo model extension.