Revealing the properties of void galaxies and their assembly using the EAGLE simulation

TL;DR

This study uses the EAGLE simulation to analyze how void galaxies differ in properties and evolution from those in denser regions, revealing environment-dependent variations in star formation, gas content, and metallicity.

Contribution

It provides a detailed comparison of void and denser environment galaxies across different stellar mass ranges, highlighting environmental effects on galaxy properties and assembly histories.

Findings

Void galaxies with low halo mass have lower stellar mass and star formation.

Inner void galaxies show distinct metallicity and gas fraction trends based on stellar mass.

Void environment influences merger history and feedback processes.

Abstract

We explore the properties of central galaxies living in voids using the EAGLE cosmological hydrodynamic simulations. Based on the minimum void-centric distance, we define four galaxy samples: inner void, outer void, wall, and skeleton. We find that inner void galaxies with host halo masses $<10^{12}M_\odot$ have lower stellar mass and stellar mass fractions than those in denser environments, and the fraction of galaxies with star formation (SF) activity and atomic hydrogen (HI) gas decreases with increasing void-centric distance, in agreement with observations. To mitigate the influence of stellar (halo) mass, we compare inner void galaxies to subsamples of fixed stellar (halo) mass. Compared to denser environments, inner void galaxies with $M_{*}= 10^{[9.0-9.5]}M_\odot$ have comparable SF activity and HI gas fractions, but the lowest quenched galaxy fraction. Inner void galaxies with $M_{*}= 10^{[9.5-10.5]}M_\odot$ have the lowest HI gas fraction, the highest quenched fraction and the lowest gas metallicities. On the other hand, inner void galaxies with $M_{*}>10^{10.5}M_\odot$ have comparable SF activity and HI gas fractions to their analogues in denser environments. They retain the highest metallicity gas that might be linked to physical processes that act with lower efficiency in underdense regions, such as AGN feedback. Furthermore, inner void galaxies have the lowest fraction of positive gas-phase metallicity gradients, which are typically associated with external processes or feedback events, suggesting they have more quiet merger histories than galaxies in denser environments. Our findings shed light on how galaxies are influenced by their large-scale environment.