Dynamical Evolution of Voids with Surrounding Gravitational Tidal Field

TL;DR

This paper investigates how individual void shapes evolve under gravitational tidal forces using N-body simulations, revealing correlations between shape changes and tidal fields, and highlighting complexities in interpreting void shapes.

Contribution

It introduces a detailed analysis of individual void responses to tidal forces during non-linear evolution, utilizing particle tracking and advanced void identification methods.

Findings

Void ellipticity variation correlates with surrounding tidal field.

Void shape deformation can result from particle exchange, not just tidal forces.

Some voids' shapes may not accurately reflect the gravitational quadrupole field.

Abstract

The void ellipticity distribution today can be well explained by the tidal field. Going a step further from the overall distribution, we investigate individuality on the tidal response of void shape in non-linear dynamical evolution. We perform an N-body simulation and trace individual voids using particle ID. The voids are defined based on Voronoi tessellation and watershed algorithm, using public code VIDE. A positive correlation is found between the time variation of void ellipticity and tidal field around a void if the void maintains its constituent particles. Such voids tend to have smaller mass densities. Conversely, not a few voids significantly deform by particle exchange, rather than the tidal field. Those voids may prevent us from correctly proving a quadrupole field of gravity out of a void shape.