Non-local halo bias with and without massive neutrinos

TL;DR

This paper investigates non-local halo bias in cosmologies with massive neutrinos, using third-order perturbation theory and peak-background split, achieving accurate modeling of scale-dependent bias up to moderate scales.

Contribution

It extends perturbation theory to include non-local terms and applies this to neutrino cosmologies, providing precise bias modeling without free parameters.

Findings

Non-local terms are crucial for accurate bias modeling.

The model fits numerical data within a few percent up to k=0.3 h/Mpc.

Inclusion of Lagrangian k^2 terms improves fit accuracy.

Abstract

Understanding the biasing between the clustering properties of halos and the underlying dark matter distribution is important for extracting cosmological information from ongoing and upcoming galaxy surveys. While on sufficiently larges scales the halo overdensity is a local function of the mass density fluctuations, on smaller scales the gravitational evolution generates non-local terms in the halo density field. We characterize the magnitude of these contributions at third-order in perturbation theory by identifying the coefficients of the non-local invariant operators, and extend our calculation to include non-local (Lagrangian) terms induced by a peak constraint. We apply our results to describe the scale-dependence of halo bias in cosmologies with massive neutrinos. The inclusion of gravity-induced non-local terms and, especially, a Lagrangian $k^2$-contribution is essential to reproduce the numerical data accurately. We use the peak-background split to derive the numerical values of the various bias coefficients from the excursion set peak mass function. For neutrino masses in the range $0\leq \sum_i m_{\nu_i} \leq 0.6$ eV, we are able to fit the data with a precision of a few percents up to $k=0.3\, h {\rm \,Mpc^{-1}}$ without any free parameter.