| |
 |
| Paper: |
Non-Keplerian rotation in AGNs |
| Volume: |
290, Active Galactic Nuclei: from Central Engine to Host Galaxy |
| Page: |
223 |
| Authors: |
Lodato, G.; Bertin, G. |
| Abstract: |
There is now growing observational evidence for the presence of accretion disks in the nuclei of active galaxies. In some cases, the outer regions of these disks can now be directly imaged and their rotation traced with water maser spectroscopic observations. In standard α-models the value of the axisymmetric stability parameter Q would decrease rapidly with increasing radius, and eventually become much smaller than unity. This proves that the self-gravity of the disk should modify the relevant physical processes in the outer disk regions, where non-self-gravitating models are thus expected to fail. Here we illustrate a simple, steady-state model for a self-gravitating accretion disk, marginally stable with respect to axisymmetric Jeans instability. This model is characterized by a rotation curve which is flatter than Keplerian in the outer disk. The modified energy balance needed to bring the disk to a self-regulated state makes self-regulated disks thermally stable, even when optically thin bremsstrahlung is the dominant cooling term. Observations of the disk rotation in some Seyfert galaxy nuclei, such as that of NGC 1068, often show deviations from the Keplerian regime. Here we provide an interpretation of the observed kinematical properties of these objects in terms of our self-gravitating disk models. An interesting consequence is a quantitative estimate of the value of the long-sought parameter α. |
|
|
|
|
|
