Active galactic nucleus obscuration from winds: From dusty infrared-driven to warm and X-ray photoionized

Abstract

We present calculations of active galactic nucleus winds at parsec scales along with the associated obscuration. We take into account the pressure of infrared radiation on dust grains and the interaction of X-rays from a central black hole with hot and cold plasma. Infrared radiation (IR) is incorporated in radiation-hydrodynamic simulations adopting the flux-limited diffusion approximation. We find that in the range of X-ray luminosities L = 0.05-0.6 L Edd, the Compton-thick part of the flow (aka torus) has an opening angle of approximately 72°-75° regardless of the luminosity. At L ≳ 0.1, the outflowing dusty wind provides the obscuration with IR pressure playing a major role. The global flow consists of two phases: the cold flow at inclinations θ ≳ 70° and a hot, ionized wind of lower density at lower inclinations. The dynamical pressure of the hot wind is important in shaping the denser IR-supported flow. At luminosities ≤0.1 L Edd episodes of outflow are followed by extended periods when the wind switches to slow accretion. © 2012. The American Astronomical Society. All rights reserved..