Void Galaxies and AGN Activity in ZOBOV-identified TNG300 Voids Out to z=3.0

TL;DR

This study uses the TNG300 simulation to analyze void galaxies across redshifts up to 3, revealing their distinct properties and higher AGN activity compared to non-void galaxies, with implications for galaxy evolution in cosmic voids.

Contribution

It introduces a watershed-based void catalog in TNG300 and characterizes galaxy properties and AGN activity within different void populations across redshifts.

Findings

Void galaxies are bluer, smaller, more star-forming, and less metal-rich than non-void galaxies.

Density-controlled void galaxies exhibit significantly higher AGN fractions than non-void galaxies.

Differences in galaxy properties are less pronounced at redshifts ≥ 1 due to resolution and selection effects.

Abstract

We study void galaxies in the TNG300 simulation between redshifts $z=3$ and $z=0$. Cosmic void catalogs were constructed using a watershed-based void-finding algorithm, and we define four populations of field galaxies for our investigation: [1] galaxies that are members of a watershed void, [2] galaxies that are located within a radius $r \leq 0.8 R_{\rm eff}$ of the center of a void, [3] galaxies interior to spheres centered on void centers that have underdensity contrasts $<-0.8$, and [4] non-void galaxies. We show that population statistics on void galaxy properties can be recovered from watershed-based void catalogs. Differences between galaxy populations are most pronounced interior to the shell-crossing surface (i.e., population [3]) where densities are intermediate to high. Compared to non-void galaxies at all redshifts, the density controlled galaxies are bluer, smaller, more actively star forming, more massive, and less metal enriched. At redshifts $\geq 1$, these differences are less apparent, likely caused by resolution and selection effects incurred by attempting to define a density-controlled sample from a watershed-based void finding algorithm. Further, we investigate the fraction of galaxies with Active Galactic Nuclei (AGN) and find that our density controlled population has AGN fractions that are significantly higher than those of non-void galaxy population ($79.8 \pm 0.4$\% higher at $z=0.0$ and $61.5\pm 0.7$\% higher at larger redshifts).