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The Accretion Geometry in Radio-Loud Active Galaxies

David Ballantyne, The University of Arizona

I review the latest attempts to determine the accretion geometry in radio-loud AGN. Multiwavelength surveys have shown that radio-loudness is more common in low-luminosity AGN than in higher luminosity Seyfert galaxies or quasars. These low-luminosity AGN have small enough accretion rates that they are most likely accreting via a geometrically thick and radiatively inefficient accretion flow. I emphasize the role of X-ray spectroscopic observations to determine the accretion geometry of the higher luminosity broad-line radio galaxies. Observations of this kind are needed to determine the importance of the black hole spin in jet production. I suggest that there are three conditions to jet formation that must be satisfied: the presence of a rapidly spinning black hole, an accretion flow with a large H/r ratio, and a favorable magnetic field geometry.