Published in PASP, 112, 1145, 2000.
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BROAD IRON LINES IN ACTIVE GALACTIC NUCLEI

A.C. Fabian 1, K. Iwasawa 1, C.S. Reynolds 2, 3, A.J. Young 4


Abstract. An intrinsically narrow line emitted by an accretion disk around a black hole appears broadened and skewed as a result of the Doppler effect and gravitational redshift. The fluorescent iron line in the X-ray band at 6.4 - 6.9 keV is the strongest such line and is seen in the X-ray spectrum of many active galactic nuclei and, in particular, Seyfert galaxies. It is an important diagnostic with which to study the geometry and other properties of the accretion flow very close to the central black hole. The broad iron line indicates the presence of a standard thin accretion disk in those objects, often seen at low inclination. The broad iron line has opened up strong gravitational effects around black holes to observational study with wide-reaching consequences for both astrophysics and physics.


Table of Contents

INTRODUCTION

THE BASICS OF THE BROAD IRON LINE
Line Production
Elemental Abundance
Inclination Angle
Ionization of the Disk Surface
The Profile of the Broad Iron Line
Observations of Broad Iron Lines

ALTERNATIVE MODELS FOR A BROAD LINE

WHAT HAPPENS INSIDE 6 rg: KERR BLACK HOLES

REVERBERATION

OTHER TYPES OF BLACK HOLE SYSTEMS
Quasars
Low Luminosity AGN
Radio-loud AGN
Galactic Black Hole Candidates

SUMMARY

REFERENCES



1 Institute of Astronomy, Madingley Road, Cambridge CB3 0HA UK

2 JILA, University of Colorado, Boulder CO 80309

3 Hubble Fellow

4 Department of Astronomy, University of Maryland, College Park MD 20742

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