Dense Clouds near the Center of Active Galactic Nuclei
Abstract
A model is presented which assumes the existence of 'cold' (not completely ionized) dense clouds near the central engine of Active Galactic Nuclei (AGN). The presence of such cold matter so close to the central engine is a logical interpretation of the results of x-ray observations of Seyfert nuclei by the EXOSAT and GINGA missions. The geometrical distribution of this matter is determined by its accretion rate, the mass of the central compact object and the magnitude of the confining magnetic fields, which are assumed to be of virial-strength. We show that this matter may assume the shape of clouds, sheets and fillaments. We use the luminosity, the fastest variability and the absorption coloumn density of a source to derive self consistant equations of state for the clouds, in which the temperature, density and covering factor depend on the distance from the central source. The effects of such clouds on the observed spectrum and lightcurve are calculated, using Monte Carlo integration methods. It is shown that this model is consistent with the complicated observed spectra and variability behavior of the most extensively studied Seyfert nuclei. The results are compared with other proposed models. The existing observational evidence appears to favor the `cloud-model'.
- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1992
- Bibcode:
- 1992AAS...181.8402S