Zusammenfassung
We present an analysis of the galaxy-scale gaseous outflows from the FIRE
(Feedback in Realistic Environments) simulations. This suite of hydrodynamic
cosmological zoom simulations provides a sample of halos where star-forming
giant molecular clouds are resolved to z=0, and features an explicit stellar
feedback model on small scales. In this work, we focus on quantifying the gas
mass ejected out of galaxies in winds and how this material travels through the
halo. We correlate these quantities to star formation in galaxies throughout
cosmic history. Our simulations reveal that a significant portion of every
galaxy's evolution, particularly at high redshift, is dominated by bursts of
star formation, which are followed by powerful gusts of galactic outflow that
sweep up a large fraction of gas in the interstellar medium and send it through
the circumgalactic medium. The dynamical effect of these outflows can
significantly limit the amount of star formation within the affected galaxy. At
low redshift, however, sufficiently massive galaxies corresponding to
L*-progenitors develop stable disks and switch into a continuous and quiescent
mode of star formation that does not drive outflows into the halo. We find
inflow to be more continuous than outflow, although filamentary accretion onto
the galaxy can be temporarily disrupted by recently ejected outflows. Using a
variety of techniques, we measure outflow rates and use them to derive
mass-loading factors, and their dependence on circular velocity, halo mass, and
stellar mass for a large sample of galaxies in the FIRE simulation suite,
spanning four decades in halo mass, six decades in stellar mass, and a redshift
range of 4.0 > z > 0. Mass-loading factors for L*-progenitors are eta ~= 10 at
high redshift, but decrease to eta << 1 at low redshift. continued in text
Nutzer