How Supernovae Launch Galactic Winds
  We use idealized three-dimensional hydrodynamic simulations of global
galactic discs to study the launching of galactic winds by supernovae (SNe).
The simulations resolve the cooling radii of the majority of supernova remnants
(SNRs) and thus self-consistently capture how SNe drive galactic winds. We find
that SNe launch highly supersonic winds with properties that agree reasonably
well with expectations from analytic models. The energy loading ($\eta_E =
\dot{E}_{\rm wind} / \dot{E}_{\rm SN}$) of the winds in our simulations are
well converged with spatial resolution while the wind mass loading ($\eta_M =
\dot{M}_{\rm wind} / \dot{M}_\star$) decreases with resolution at the
resolutions we achieve. We present a simple analytic model based on the concept
that SNRs with cooling radii greater than the local scale height breakout of
the disc and power the wind. This model successfully explains the dependence
(or lack thereof) of $\eta_E$ (and by extension $\eta_M$) on the gas surface
density, star formation efficiency, disc radius, and the clustering of SNe. The
winds in the majority of our simulations are weaker than expected in reality,
likely due to the fact that we seed SNe preferentially at density peaks.
Clustering SNe in time and space substantially increases the wind power.
