Turbulent AGN tori

TL;DR

This paper combines hydrodynamical simulations and radiative transfer modeling to explore the structure and observable properties of AGN tori, revealing a filamentary, turbulent, and multi-component geometry consistent with recent interferometric observations.

Contribution

It introduces a novel simulation approach integrating stellar feedback, hydrodynamics, and radiative transfer to model AGN tori in detail, aligning with observational data.

Findings

Filamentary large-scale torus structure forms naturally from stellar feedback.

Dense, turbulent disk component surrounds the filamentary torus.

Model results agree well with interferometric and spectral observations.

Abstract

Recently, the MID-infrared Interferometric instrument (MIDI) at the VLTI has shown that dust tori in the two nearby Seyfert galaxies NGC 1068 and the Circinus galaxy are geometrically thick and can be well described by a thin, warm central disk, surrounded by a colder and fluffy torus component. By carrying out hydrodynamical simulations with the help of the TRAMP code (Klahr et al. 1999), we follow the evolution of a young nuclear star cluster in terms of discrete mass-loss and energy injection from stellar processes. This naturally leads to a filamentary large scale torus component, where cold gas is able to flow radially inwards. The filaments open out into a dense and very turbulent disk structure. In a post-processing step, we calculate observable quantities like spectral energy distributions or images with the help of the 3D radiative transfer code MC3D (Wolf 2003). Good agreement is found in comparisons with data due to the existence of almost dust-free lines of sight through the large scale component and the large column densities caused by the dense disk.