Accretion Disks and Dust Disks in Active Elliptical Galaxies

We aim here to study the relation between optical/radio nuclear activity and resolvable dust/gas disks in active ellipticals. We will do this by analyzing a complete, unbiased sample of 112 galaxies chosen on a nearly isotropic property, the diffuse radio flux at 178 MHz. In order to understand the significance of the detected dust in the active ellipticals, we will also analyze a control sample of 135 normal ellipticals matched in starlight luminosity and central surface brightness for comparison. The inner dust structures which probe the effects described here appear on very small scales and generally cannot be observed from the ground. The relative position angle between the radio axis and the dust disk serves as a powerful diagnostic; the orientation of the outer dust disk has the potential to reveal the history of a triggering merger, while the orientation of the innermost dust disk reveals the structure of the accretion disk on 10-100 pc scale. Finally, the radio jet indicates the innermost axis which is generated on scales of 100 R_G or less. With a sample that includes FRI's, FRII's {with luminous active nuclei and ``optically dull"}, and normal elliptical galaxies, we can test predictions for the causes of activity, current ideas about the dynamics of the gas/dust involved in mergers, and probe the physics of the resulting accretion disks.