Ultraviolet and X-ray observations of active galactic nuclei: Constraints on models of the broad emission line region

摘要

The extensive ultraviolet spectra of broad line active nuclei and the large body of X-ray photometry and spectroscopy of these objects and the constraints that these data place on the photoionization models of the broad emission line region (BLR) are considered. Many active galactic nuclei, in particular quasars and Seyfert I's, are characterized by strong, broad (full width 2000 km/sec), emission lines from permitted transitions in abundant elements. In the simplist models these lines originate in clouds located at some characteristic distance from the central ionizing source in a quasi-spherical distribution. While the dynamics of these clouds are quite important, the emphasis is on how to derive the observed line strengths and line ratios.