DETECTING ACCRETION DISKS IN ACTIVE GALACTIC NUCLEI

Recent X-ray observations of active galactic nuclei with ASCA suggest that we may be observing Fe-K line emission from very close to the cen tral black-black hole. We provide here the relevant formalism to inter pret those observations. We show how to model the appearance of an acc retion disk around a rotating black hole and line profiles from disk e mission. We try to present in a coherent way results that are scattere d in the litterature and/or that are limited to particular cases. We e xtend these results to the more general case of a rotating black hole (Kerr metric). We finally discuss the relation of the full width at ze ro intensity of the line to the angular momentum of the black hole.