Properties of simulated galaxies and supermassive black holes in cosmic
  voids
  Cosmic voids, the under-dense regions of the cosmic web, are widely used to
constrain cosmology. Voids contain few, isolated galaxies, presumably expected
to be less evolved and preserving memory of the pristine Universe. We use the
cosmological hydrodynamical simulation Horizon-AGN coupled to the void finder
{\sc \texttt{VIDE}} to investigate properties of galaxies in voids at z=0. We
find that, closer to void centers, low-mass galaxies are more common than their
massive counterparts. At fixed dark matter halo mass, they have smaller stellar
masses than in denser regions. The star formation rate of void galaxies
diminishes when approaching void centers, but their sSFR slightly increases,
suggesting that void galaxies form stars more efficiently with respect to their
stellar mass. We find that this can not only be attributed to the prevalence of
low-mass galaxies. The inner region of voids also predominantly host low-mass
BHs. However, the BH mass to galaxy mass ratios resemble those of the whole
simulation at z=0. Our results suggest that even if the growth channels in
cosmic voids are different than in denser environments, voids grow their
galaxies and BHs in a similar way. While a large fraction of the BHs have low
Eddington ratios, we find that 20\% could be observed as AGN with log10
L=41.5-42.5 erg/s in hard X-ray (2-10 keV). These results pave the way to
future work with larger next-generation hydro simulations, aiming to confirm
our findings and prepare the application on data from upcoming large surveys
such as PFS, Euclid and WFIRST.
