Dynamics of gas and dust clouds in active galactic nuclei

TL;DR

This paper models the motion of optically thick clouds in active galactic nuclei, deriving analytical solutions for their orbits and stability criteria based on radiation anisotropy, luminosity, and cloud properties.

Contribution

It provides the first analytical solutions for cloud orbits considering anisotropic radiation and establishes stability criteria dependent on inclination, luminosity, and cloud density.

Findings

All stable orbits are closed with complex shapes.

A critical inclination determines cloud stability based on luminosity and column density.

Analytical solutions are derived for constant cloud column densities.

Abstract

We analyse the motion of single optically thick clouds in the potential of a central mass under the influence of an anisotropic radiation field ~|cos(\theta)|, a model applicable to the inner region of active galactic nuclei. Resulting orbits are analytically soluble for constant cloud column densities. All stable orbits are closed, although they have non-trivial shapes. Furthermore, there exists a stability criterion in the form of a critical inclination, which depends on the luminosity of the central source and the column density of the cloud.