Bursting Bubbles: Clustered Supernova Feedback in Local and
  High-redshift Galaxies
  We compare an analytic model for the evolution of supernova-driven
superbubbles with observations of local and high-redshift galaxies, and the
properties of intact HI shells in local star-forming galaxies. Our model
correctly predicts the presence of superwinds in local star-forming galaxies
(e.g., NGC 253) and the ubiquity of outflows near $z \sim 2$. We find that
high-redshift galaxies may `capture' 20-50\% of their feedback momentum in the
dense ISM (with the remainder escaping into the nearby CGM), whereas local
galaxies may contain $\lesssim$10\% of their feedback momentum from the central
starburst. Using azimuthally averaged galaxy properties, we predict that most
superbubbles stall and fragment \emph{within} the ISM, and that this occurs at,
or near, the gas scale height. We find a consistent interpretation in the
observed HI bubble radii and velocities, and predict that most will fragment
within the ISM, and that those able to break-out originate from short dynamical
time regions (where the dynamical time is shorter than feedback timescales).
Additionally, we demonstrate that models with constant star cluster formation
efficiency per Toomre mass are inconsistent with the occurrence of outflows
from high-$z$ starbursts and local circumnuclear regions.
