Revealing the properties of void galaxies and their assembly using the
  EAGLE simulation
  We explore the properties of central galaxies living in voids using the EAGLE
cosmological hydrodynamic simulations in conjunction with the
\cite{paillas2017} void catalogue. Based on the distance to the closest void,
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 distance to their
closest void, in agreement with observations. To mitigate the influence of
stellar mass, we compare inner void galaxies to subsamples of fixed stellar
(halo) mass. Inner void galaxies with $M_{*}= 10^{[9.0-9.5]}M_\odot$ have
similar 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 lowest gas
metallicities compared to galaxies in denser environments. 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 only
fostered in underdense regions. 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 provide a unique insight into how galaxies are affected by their
large-scale environment.
