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arXiv · 1108.3766

AGN obscuration through dusty infrared dominated flows. I. Radiation-hydrodynamics solution for the wind

A. Dorodnitsyn·G. S. Bisnovatyi-Kogan·T. Kallman
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Abstract

We construct a radiation-hydrodynamics model for the obscuring toroidal structure in active galactic nuclei. In this model the obscuration is produced at parsec scale by a dense, dusty wind which is supported by infrared radiation pressure on dust grains. To find the distribution of radiation pressure, we numerically solve the 2D radiation transfer problem in a flux limited diffusion approximation. We iteratively couple the solution with calculations of stationary 1D models for the wind, and obtain the z-component of the velocity. Our results demonstrate that for AGN luminosities greater than 0.1 Ledd external illumination can support a geometrically thick obscuration via outflows driven by infrared radiation pressure. The terminal velocity of marginally Compton-thin models (0.2<tau_T<0.6), is comparable to or greater than the escape velocity. In Compton thick models the maximum value of the vertical component of the velocity is lower than the escape velocity, suggesting that a significant part of our torus is in the form of failed wind. The results demonstrate that obscuration via normal or failed infrared-driven winds is a viable option for the AGN torus problem and AGN unification models. Such winds can also provide an important channel for AGN feedback.

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A. Dorodnitsyn, G. S. Bisnovatyi-Kogan, T. Kallman. 2011-08-18. AGN obscuration through dusty infrared dominated flows. I. Radiation-hydrodynamics solution for the wind. https://doi.org/10.1088/0004-637x/741/1/29

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