The effect of massive neutrinos on the BAO peak

TL;DR

This study investigates how massive neutrinos influence the BAO peak's shape and height, using simulations and analytic models, revealing nonlinear effects that partially counteract linear theory predictions.

Contribution

It demonstrates that a simplified Zel'dovich approximation accurately models the nonlinear evolution of the BAO peak affected by neutrino masses.

Findings

Nonlinear structure formation reduces the BAO peak for higher neutrino masses.

The BAO peak decreases by ~0.6% for 0.15 eV neutrinos.

The BAO peak increases by ~1.2% for 0.3 eV neutrinos.

Abstract

We study the impact of neutrino masses on the shape and height of the BAO peak of the matter correlation function, both in real and redshift space. In order to describe the nonlinear evolution of the BAO peak we run N-body simulations and compare them with simple analytic formulae. We show that the evolution with redshift of the correlation function and its dependence on the neutrino masses is well reproduced in a simplified version of the Zel'dovich approximation, in which the mode-coupling contribution to the power spectrum is neglected. While in linear theory the BAO peak decreases for increasing neutrino masses, the effect of nonlinear structure formation goes in the opposite direction, since the peak broadening by large scale flows is less effective. As a result of this combined effect, the peak decreases by $\sim 0.6 \%$ for $ \sum m_\nu = 0.15$ eV and increases by $\sim1.2 \%$ for $ \sum m_\nu = 0.3$ eV, with respect to a massless neutrino cosmology with equal value of the other cosmological parameters. We extend our analysis to redshift space and to halos, and confirm the agreement between simulations and the analytic formulae. We argue that all analytical approaches having the Zel'dovich propagator in their lowest order approximation should give comparable performances, irrespectively to their formulation in Lagrangian or in Eulerian space.