CONES OF IONIZING-RADIATION IN ACTIVE GALAXIES - PROBING THE CENTRAL ENGINE

Highly ionized gas has been detected at large distances from the nucleus in several classes of active galaxies. There is evidence that photoionization by the active nucleus may be the most relevant mechanism for the observed ionization. The spatial distribution of such gas has a conical shape, whose vertex points towards the nucleus and the axis is closely oriented with the radio structure. This scenario suggests collimation or anisotropy of the ionizing continuum. A geometrically thick accretion disk may produce such ionizing spectrum. We use a simple model for a thick accretion disk around a supermassive black hole and a photoionization code to make theoretical predictions. Results are compared with the observational data (for radio and Seyfert galaxies). © 1990 Kluwer Academic Publishers.