The impact of stellar feedback on the density and velocity structure of
  the interstellar medium
  We study the impact of stellar feedback in shaping the density and velocity
structure of neutral hydrogen (HI) in disc galaxies. For our analysis, we carry
out $\sim 4.6$pc resolution $N$-body+adaptive mesh refinement (AMR)
hydrodynamic simulations of isolated galaxies, set up to mimic a Milky Way
(MW), and a Large and Small Magellanic Cloud (LMC, SMC). We quantify the
density and velocity structure of the interstellar medium using power spectra
and compare the simulated galaxies to observed HI in local spiral galaxies from
THINGS (The HI Nearby Galaxy Survey). Our models with stellar feedback give an
excellent match to the observed THINGS HI density power spectra. We find that
kinetic energy power spectra in feedback regulated galaxies, regardless of
galaxy mass and size, show scalings in excellent agreement with super-sonic
turbulence ($E(k)\propto k^{-2}$) on scales below the thickness of the HI
layer. We show that feedback influences the gas density field, and drives gas
turbulence, up to large (kpc) scales. This is in stark contrast to density
fields generated by large scale gravity-only driven turbulence. We conclude
that the neutral gas content of galaxies carries signatures of stellar feedback
on all scales.
