SPH Simulations of Black Hole Accretion: A Step to Model Black Hole
  Feedback in Galaxies
  (Abridged) We test how accurately the smoothed particle hydrodynamics (SPH)
numerical technique can follow spherically-symmetric Bondi accretion. Using the
3D SPH code GADGET-3, we perform simulations of gas accretion onto a central
supermassive black hole (SMBH) of mass 10^8 M_sun within the radial range of
0.1 - 200 pc. We carry out simulations without and with radiative heating by a
central X-ray corona and radiative cooling. For an adiabatic case, the radial
profiles of hydrodynamical properties match the Bondi solution, except near the
inner and outer radius of the computational domain. We find that adiabatic
Bondi accretion can be reproduced for durations of a few dynamical times at the
Bondi radius, and for longer times if the outer radius is increased. With
radiative heating and cooling included, the spherically accreting gas takes a
longer time to reach a steady-state than the adiabatic Bondi accretion runs,
and in some cases does not reach a steady-state even within several hundred
dynamical times. We find that artificial viscosity in the GADGET code causes
excessive heating near the inner radius, making the thermal properties of the
gas inconsistent with a physical solution. This overheating occurs typically
only in the supersonic part of the flow, so that it does not affect the mass
accretion rate. We see that increasing the X-ray luminosity produces a lower
central mass inflow rate, implying that feedback due to radiative heating is
operational in our simulations. With a sufficiently high X-ray luminosity, the
inflowing gas is radiatively heated up, and an outflow develops. We conclude
that the SPH simulations can capture the gas dynamics needed to study radiative
feedback provided artificial viscosity alters only highly supersonic part of
the inflow.
