AGN Dusty Tori as a Clumpy Two-Phase Medium: The 10 Micron Silicate Feature

TL;DR

This study models active galactic nuclei dusty tori as a clumpy two-phase medium to analyze the 10 micron silicate feature, revealing how dust distribution and clump arrangement influence infrared emission characteristics.

Contribution

It introduces a three-dimensional radiative transfer model of clumpy two-phase dusty tori, providing new insights into the silicate feature variability in AGN infrared spectra.

Findings

Dust distribution affects silicate feature shape and strength.

Clump arrangement influences the emission profile.

Smooth and clumpy models can both produce diverse silicate features.

Abstract

We investigated the emission of active galactic nuclei dusty tori in the infrared domain, with a focus on the 10 micron silicate feature. We modeled the dusty torus as a clumpy two-phase medium with high-density clumps and a low-density medium filling the space between the clumps. We employed a three-dimensional radiative transfer code to obtain spectral energy distributions and images of tori at different wavelengths. We calculated a grid of models for different parameters and analyzed the influence of these parameters on the shape of the mid-infrared emission. A corresponding set of clumps-only models and models with a smooth dust distribution is calculated for comparison. We found that the dust distribution, the optical depth and a random arrangement of clumps in the innermost region, all have an impact on the shape and strength of the silicate feature. The 10 micron silicate feature can be suppressed for some parameters, but models with smooth dust distribution are also able to produce a wide range of the silicate feature strength.