Non-Sobolev modelling of radiation pressure driven flows in Active Galactic Nuclei

Abstract

We present a new general scheme for calculating the structure and dynamics of radiation pressure driven, photoionized flows. The new method goes one step beyond the Sobolev approximation. It involves a numerical solution of the radiative transfer in absorption lines including the effects of differential expansion and line interactions such as line locking and blanketing. We also present a new scheme for calculating the radiation pressure due to trapped line photons in finite, differentially expanding flows. We compare our results for the radiation pressure force with those obtained using the Sobolev approximation and show the limitations of the latter. In particular, we demonstrate that the Sobolev method gives a poor approximation near discontinuity surfaces and its neglect of line blanketing can lead to erroneous results in high velocity flows. We combine the newly calculated radiation pressure force with self-consistent photoionization and thermal calculations to study the dynamics and spectral features of broad absorption line flows and highly ionized gas flows in AGN. A comparison with Sobolev-type calculations shows that the latter over estimates the flow's terminal velocity and, conversely, under estimates its opacity. We also show that line locking on broad emission lines can have a significant effect on the dynamics and spectral features of AGN flows.

12 pages, 14 figures; includes an erratum on page 12 which corrects an erroneous reference to the work of Elitzur & Ferland (1986)

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Cited by in corpus (10)

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• Radiative Transfer and Acceleration in Magnetocentrifugal Winds
• Dynamical and Spectral Modeling of the Ionized Gas and Nuclear Environment in NGC 3783
• Dramatic X-ray Spectral Variability of the Broad Absorption Line Quasar PG2112+059
• Feedback from supercritical disk accretion flows; Two-dimensional radiation-hydrodynamic simulations of stable and unstable disks with radiatively driven outflows
• SDSS J094533.99+100950.1 - the remarkable weak emission line quasar
• Large-Scale Parker Winds in Active Galactic Nuclei
• Metal enrichment by radiation pressure in active galactic nucleus outflows -- theory and observations
• Hubble Space Telescope [O III] Emission-Line Kinematics in Two Nearby QSO2s: A Case for X-ray Feedback
• On the Steady Nature of Line-Driven Disk Winds: Application to Cataclysmic Variables