Broad Iron Lines in AGN

Kirpal Nandra, Imperial College London

Observations of broad iron lines in AGN have the potential to be an important diagnostic of the black hole/accretion disk system at the smallest radii. After a brief historical review, the state of the art of these observations will be presented and discussed. Several mysteries remain, such as the apparent lack of significant broad emission in some objects, and a framework in which all observations can be explained is still lacking. Some possible pathways towards future progress will be outlined.