A Stellar Feedback Origin for Neutral Hydrogen in High-Redshift
  Quasar-Mass Halos
  Observations reveal that quasar host halos at z~2 have large covering
fractions of cool dense gas (>~60% for Lyman limit systems within a projected
virial radius). Most simulations have so far have failed to explain these large
observed covering fractions. We analyze a new set of 15 simulated massive halos
with explicit stellar feedback from the FIRE project, covering the halo mass
range M_h~2x10^12-10^13 Msun at z=2. This extends our previous analysis of the
circum-galactic medium of high-redshift galaxies to more massive halos. AGN
feedback is not included in these simulations. We find Lyman limit system
covering fractions consistent with those observed around quasars. The large HI
covering fractions arise from star formation-driven galactic winds, including
winds from low-mass satellite galaxies that interact with cosmological
filaments. We show that it is necessary to resolve these satellite galaxies and
their winds to reproduce the large Lyman limit system covering fractions
observed in quasar-mass halos. Our simulations predict that galaxies occupying
dark matter halos of mass similar to quasars but without a luminous AGN should
have Lyman limit system covering fractions comparable to quasars.
