In-N-Out: the gas cycle from dwarfs to spiral galaxies
  We examine the scalings of galactic outflows with halo mass across a suite of
twenty high-resolution cosmological zoom galaxy simulations covering halo
masses from 10^9.5 - 10^12 M_sun. These simulations self-consistently generate
outflows from the available supernova energy in a manner that successfully
reproduces key galaxy observables including the stellar mass-halo mass,
Tully-Fisher, and mass-metallicity relations. We quantify the importance of
ejective feedback to setting the stellar mass relative to the efficiency of gas
accretion and star formation. Ejective feedback is increasingly important as
galaxy mass decreases; we find an effective mass loading factor that scales as
v_circ^(-2.2), with an amplitude and shape that is invariant with redshift.
These scalings are consistent with analytic models for energy-driven wind,
based solely on the halo potential. Recycling is common: about half the outflow
mass across all galaxy masses is later re-accreted. The recycling timescale is
typically about 1 Gyr, virtually independent of halo mass. Recycled material is
re-accreted farther out in the disk and with typically about 2-3 times more
angular momentum. These results elucidate and quantify how the baryon cycle
plausibly regulates star formation and alters the angular momentum distribution
of disk material across the halo mass range where most of cosmic star formation
occurs.
