http://arxiv.org/abs/1402.1849
Accretion disk winds are thought to produce many of the characteristic features seen in the spectra of active galactic nuclei (AGN) and quasi-stellar objects (QSOs). These outflows also represent a natural form of feedback between the central supermassive black hole and its host galaxy. The mechanism for driving this mass loss remains unknown, although radiation pressure mediated by spectral lines is a leading candidate. Here, we calculate the ionization state of, and emergent spectra for, the hydrodynamic simulation of a line-driven disk wind previously presented by Proga & Kallman (2004). To achieve this, we carry out a comprehensive Monte Carlo simulation of the radiative transfer through, and energy exchange within, the predicted outflow. We find that the wind is much more ionized than originally estimated. This is because it is much more difficult to shield any wind regions effectively when the outflow itself is allowed to reprocess and redirect ionizing photons. As a result, the wind no longer produces the broad ultraviolet spectral lines that are observed in many AGN/QSOs. In fact, it is unlikely that this particular simulated outflow could exist at all, since the efficiency of line-driving is very sensitive to the ionization state of the gas. To obtain a self-consistent model of line-driven disk winds in AGN/QSO, it is therefore critical to include a more detailed treatment of radiative transfer and ionization in the next generation of hydrodynamic simulations.
N. Higginbottom, D. Proga, C. Knigge, et. al.
Tue, 11 Feb 14
29/55
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