Voids in massive neutrino cosmologies

TL;DR

This study investigates how massive neutrinos influence the properties of cosmic voids, revealing that neutrino mass affects void size, density, and velocity profiles, and breaks degeneracies present in other cosmological measurements.

Contribution

It provides a comprehensive numerical analysis of void properties in massive neutrino cosmologies, combining N-body simulations and galaxy modeling to identify unique neutrino effects.

Findings

Massive neutrinos lead to more small voids and fewer large voids.

Void profiles are less evacuated in massive neutrino cosmologies.

Neutrino effects are detectable in matter density and velocity profiles around voids.

Abstract

Cosmic voids are a promising environment to characterize neutrino-induced effects on the large-scale distribution of matter in the universe. We perform a comprehensive numerical study of the statistical properties of voids, identified both in the matter and galaxy distributions, in massive and massless neutrino cosmologies. The matter density field is obtained by running several independent $N$-body simulations with cold dark matter and neutrino particles, while the galaxy catalogs are modeled by populating the dark matter halos in simulations via a halo occupation distribution (HOD) model to reproduce the clustering properties observed by the Sloan Digital Sky Survey (SDSS) II Data Release 7. We focus on the impact of massive neutrinos on the following void statistical properties: number density, ellipticities, two-point statistics, density and velocity profiles. Considering the matter density field, we find that voids in massive neutrino cosmologies are less evolved than those in the corresponding massless neutrinos case: there is a larger number of small voids and a smaller number of large ones, their profiles are less evacuated, and they present a lower wall at the edge. Moreover, the degeneracy between $\sigma_8$ and $\Omega_{\nu}$ is broken when looking at void properties. In terms of the galaxy density field, we find that differences among cosmologies are difficult to detect because of the small number of galaxy voids in the simulations. Differences are instead present when looking at the matter density and velocity profiles around these voids.