Hyper-Eddington accretion flows onto black holes accompanied by powerful
  outflows
  We perform two-dimensional radiation hydrodynamical simulations of accretion
flows onto black holes (BHs) at the nuclei of protogalaxies, and study the
impact of mechanical and radiative feedback on rapid growth of BHs. The
outflows deposit mass, momentum and energy into the surrounding medium and
prevent mass accretion onto the BH, resulting in the reduction of radiative
output. We find that when the BH is embedded in a dense gas core, ionizing
radiation attenuated by inefficient BH feeding owing to mechanical feedback
hardly affects the gas dynamics at the BH gravitational sphere of influence,
from which intense inflows of neutral gas occur at rates substantially
exceeding the Eddington limit without impeded by photoionization and heating.
Since mechanical power of outflows driven by the rapidly accreting BH is
sufficiently strong, bipolar outflows completely evacuate the surrounding gas
in the polar region but mass inflows through the equatorial region maintain the
BH accretion rate as high as $\sim 300-10^3~\dot{M}_{\rm Edd}$, which is
reduced by one order of magnitude from those with radiative feedback alone.
Furthermore, we find that the critical gas density required for rapid accretion
is lower by a factor of $\sim 3$ nearly independently of BH mass, when
mechanical feedback is considered. By studying the dependence on outflow model
parameters (e.g., opening angle, mass-loading degree into outflows, velocity),
we conclude that contrary to naive expectation, the existence of stronger
outflow leads to the transition to rapid accretion phases more efficiently.
Rapidly growing BHs inject mechanical power with $\sim 0.1-1\%$ of the
radiative luminosity into their host galaxy scales, which is used for
cosmological simulations.
