  Galactic outflows driven by supernovae (SNe) are thought to be a powerful
regulator of a galaxy's star-forming efficiency. Mass, energy, and metal
outflows ($\eta_M$, $\eta_E$, and $\eta_Z$, here normalized by the star
formation rate, the SNe energy and metal production rates, respectively) shape
galaxy properties by both ejecting gas and metals out of the galaxy and by
heating the circumgalactic medium (CGM), preventing future accretion.
Traditionally, models have assumed that galaxies self-regulate by ejecting a
large fraction of the gas which enters the interstellar medium (ISM), even
though such high mass-loadings are in growing tension with observations. To
better understand how the relative importance of ejective (i.e. high
mass-loading) vs preventative (i.e. high energy-loading) feedback affects the
present-day properties of galaxies, we develop a simple gas-regulator model of
galaxy evolution, where the stellar mass, ISM, and CGM are modeled as distinct
reservoirs which exchange mass, metals, and energy at different rates within a
growing halo. Focusing on the halo mass range from $10^{10}$ to $10^{12}
M_{\odot}$, we demonstrate that, with reasonable parameter choices, we can
reproduce the stellar-to-halo mass relation and the ISM-to-stellar mass
relation with low mass-loaded ($\eta_M \sim 0.1-10$) but high energy-loaded
($\eta_E \sim 0.1-1$) winds, with self-regulation occurring primarily through
heating and cooling of the CGM. We show that the model predictions are robust
against changes to the mass-loading of outflows but are quite sensitive to our
choice of the energy-loading, preferring $\eta_E \sim 1$ for the lowest mass
halos and $\sim 0.1$ for Milky Way-like halos.
