In "The Central Engine of Active Galactic Nuclei", ASP Conference Series, Vol. 373, Xi'an, China, 16-21 October, 2007, eds. L. C. Ho and J.-M. Wang

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DUST IN ACTIVE GALACTIC NUCLEI

Aigen Li


Department of Physics and Astronomy, University of Missouri, Columbia, MO 65211, USA; email: lia@missouri.edu


Abstract. Dust plays an essential role in the unification theory of active galactic nuclei (AGNs). This review summarizes our current understanding of the extinction and infrared emission properties of the circumnuclear dust in AGNs as well as the inferred dust composition and size distribution.


Table of Contents

INTRODUCTION: ARE ALL AGNS BORN EQUAL? - THE ROLE OF DUST IN THE UNIFIED SCHEMES OF AGNs

EXTINCTION - A POWERFUL DISCRIMINATOR OF DUST SIZE
Interstellar Extinction: Milky Way, SMC, and LMC
AGN Extinction - "Gray" or SMC-like Extinction?

DUST SPECTROSCOPY - DIAGNOSIS OF DUST COMPOSITION
The 2175 Å Extinction Bump
The 3.4 µm Aliphatic Hydrocarbon Absorption Feature
The 9.7 µm and 18 µm Silicate Absorption and Emission Features
The 3.3, 6.2, 7.7, 8.6 and 11.3 µm PAH Emission Features
The Ice Absorption Features

IR EMISSION MODELING - INFERRING DUST SIZE AND TORUS GEOMETRY?

REFERENCES

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