Synthetic X-ray spectra for simulations of the dynamics of an accretion flow irradiated by a quasar. (arXiv:1207.7194v1 [astro-ph.HE]):
Ultraviolet and X-ray observations show evidence of outflowing gas around
many active galactic nuclei. Some of these outflows may be driven off gas
infalling towards the central black hole. We perform radiative transfer
calculations to compute the gas ionization state and X-ray spectra for two- and
three-dimensional (3D) hydrodynamical simulations of this outflow-from-inflow
scenario. By comparison with observations, our results can be used to test the
theoretical models and guide future numerical simulations. We predict both
absorption and emission features, most of which are formed in a polar funnel of
outflowing gas. This outflow causes strong absorption for observer orientation
angles of < 35 degrees. Particularly in 3D, the strength of this absorption
varies significantly for different lines-of-sight owing to the fragmentary
structure of the gas flow. Although infalling material occupies a large
fraction of the simulation volume, we do not find that it imprints strong
absorption features since the ionization state is very high. Thus, an absence
of observed inflow absorption features does not exclude the models. The main
spectroscopic consequence of the infalling gas is a scattered continuum
component that partially re-fills the absorption features caused by the
outflowing polar funnel. Fluorescence and scattering in the outflow is
predicted to give rise to several emission features for all observer
orientations. For the hydrodynamical simulations considered we find both
ionization states and column densities for the outflowing gas that are too high
to be quantitatively consistent with well-observed X-ray absorption systems.
Nevertheless, our results are qualitatively encouraging and further exploration
of the model parameter space is warranted. (Abridged.)
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