AGN obscuration from winds: from dusty infrared-driven to warm and X-ray photoionized

TL;DR

This paper models AGN winds at parsec scales, showing how infrared radiation and X-ray interactions influence obscuration and wind structure, revealing a two-phase flow with implications for AGN unification.

Contribution

It introduces radiation-hydrodynamic simulations including IR and X-ray effects to study AGN wind obscuration and structure at parsec scales.

Findings

The torus has an opening angle of 72-75 degrees across luminosities.

IR pressure significantly contributes to obscuration at L > 0.1 L_edd.

The flow consists of a cold, dusty wind and a hot, ionized wind with distinct roles.

Abstract

We present calculations of AGN 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 degrees regardless of the luminosity. At L > 0.1 L_edd 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 \theta > 70 degrees 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.