Halo abundances and shear in void models

TL;DR

This paper investigates how background shear in void models influences dark matter halo formation, using N-body simulations and an extended halo mass function, suggesting potential observational constraints on inhomogeneous cosmologies.

Contribution

The authors extend the halo mass function formalism to inhomogeneous void models and demonstrate its accuracy and implications for constraining background shear through cluster counts.

Findings

Extended halo mass function matches simulation data across scales.

Background shear impacts the growth of perturbations.

Cluster counts could constrain inhomogeneous model parameters.

Abstract

We study the non-linear gravitational collapse of dark matter into halos through numerical N-body simulations of Lemaitre-Tolman-Bondi void models. We extend the halo mass function formalism to these models in a consistent way. This extension not only compares well with the simulated data at all times and radii, but it also gives interesting clues about the impact of the background shear on the growth of perturbations. Our results give hints about the possibility of constraining the background shear via cluster number counts, which could then give rise to strong constraints on general inhomogeneous models, of any scale.