Radiation hydrodynamics simulations of the evolution of the diffuse
  ionized gas in disc galaxies
  There is strong evidence that the diffuse ionized gas (DIG) in disc galaxies
is photoionized by radiation from UV luminous O and B stars in the galactic
disc, both from observations and detailed numerical models. However, it is
still not clear what mechanism is responsible for providing the necessary
pressure support for a diffuse gas layer at kpc-scale above the disc. In this
work we investigate if the pressure increase caused by photoionization can
provide this support. We run self-consistent radiation hydrodynamics models of
a gaseous disc in an external potential. We find that photoionization feedback
can drive low levels of turbulence in the dense galactic disc, and that it
provides pressure support for an extended diffuse gas layer. Our results show
that there is a natural fine-tuning between the total ionizing radiation budget
of the sources in the galaxy and the amount of gas in the different ionization
phases of the ISM, and provide the first fully consistent radiation
hydrodynamics model of the DIG.
