Global Simulations of Galactic Discs: Violent Feedback from Clustered
  Supernovae during Bursts of Star Formation
  A suite of idealised, global, gravitationally unstable, star-forming galactic
disc simulations with 2 pc spatial resolution, performed with the adaptive mesh
refinement code {\sc ramses} is used in this paper to predict the emergent
effects of supernova feedback. The simulations include a simplified
prescriptions for formation of single stellar populations of mass $\sim 100 \,
M_{\odot}$, radiative cooling, photoelectric heating, an external gravitational
potential for a dark matter halo and an old stellar disc, self-gravity, and a
novel implementation of supernova feedback. The results of these simulations
show that gravitationally unstable discs can generate violent supersonic winds
with mass loading factors $\eta \gtrsim 10$, followed by a galactic fountain
phase. These violent winds are generated by highly clustered supernovae
exploding in dense environments created by gravitational instability, and they
are not produced in simulation without self-gravity. The violent winds
significantly perturb the vertical structure of the disc, which is later
re-established during the galactic fountain phase. Gas resettles into a
quasi-steady, highly turbulent disc with volume-weighted velocity dispersion
$\sigma > 50 \, {\rm km/s}$. The new configuration drives weaker galactic winds
with mass loading factor $\eta \leq 0.1$. The whole cycle takes place in $\leq
10$ dynamical times. Such high time variability needs to be taken into account
when interpreting observations of galactic winds from starburst and
post-starburst galaxies.
