The Impact of Wind Scalings on Stellar Growth and the Baryon Cycle in
  Cosmological Simulations
  Many phenomenologically successful cosmological galaxy formation simulations
employ kinetic winds to model galactic outflows, a crucial ingredient in
obtaining predictions that agree with various observations. Yet systematic
studies of how variations in kinetic wind scalings might alter observable
galaxy properties are rare. Here we employ GADGET-3 simulations to study how
the baryon cycle, stellar mass function, and other galaxy and CGM predictions
vary as a function of the assumed outflow speed $v_w$ and the scaling of the
mass loading factor $\eta$ with velocity dispersion $\sigma$. We design our
fiducial model to reproduce the measured wind properties at 25% of the virial
radius from the Feedback In Realistic Environments (FIRE) simulations. We find
that a strong dependence of $\eta \sim \sigma^5$ in low mass haloes with
$\sigma < 106\ \mathrm{km\ s^{-1}}$ is required to match the faint end of the
stellar mass functions at $z > 1$. The wind speed also has a major impact, with
faster winds significantly reducing wind recycling and heating more halo gas.
Both effects result in less stellar mass growth in massive haloes and impact
high ionization absorption in halo gas. We cannot simultaneously match the
stellar content at $z=2$ and $z=0$ within a single model, suggesting that an
additional feedback source such as AGN might be required in massive galaxies at
lower redshifts, but the amount needed depends strongly on assumptions
regarding the outflow properties. We run a 50 $\mathrm{Mpc/h}$, $2\times576^3$
simulation with our fiducial parameters and show that it matches a range of
star-forming galaxy properties at $z\sim0-2$. In closing, the results from
simulations of galaxy formation are much more sensitive to small changes in the
feedback implementation than to the hydrodynamic technique.
