3D radiation hydrodynamics of a dynamical torus

Abstract

We have developed a new dynamical model of the torus region in active galactic nuclei (AGNs), using a three-dimensional radiation hydrodynamics algorithm. These new simulations have the specific aim to explore the role of radiatively driven outflows, which is hotly debated in current literature as a possible explanation for the observed IR emission from the polar regions of AGNs. In this first paper, we only consider radiative effects induced by the primary radiation from the AGN. The simulations generate a disk and outflow structure that qualitatively agrees with observations, although the outflow is radial rather than polar, likely due to the lack of radiation pressure from hot dust. We find cutoffs between the wind and disk at gas temperatures of 1000 K and dust temperatures of 100 K, producing kinematic signatures that can be used for interpretation of high-resolution IR observations. We also produce line emission maps to aid in the interpretation of recent ALMA observations and future James Webb Space Telescope observations. We investigate a number of simulation parameters and find that the anisotropy of the radiation field is equally important to the Eddington factor, despite the anisotropy often being assumed to have a single, sometimes arbitrary form in many previous works. We also find that supernovae can have a small but significant impact, but only at extremely high star formation rates.

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ORCID for David Williamson: orcid.org/0000-0002-5168-7979

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