THEORETICAL EMISSION-LINE PROFILES OF ACTIVE GALACTIC NUCLEI AND THE UNIFIED MODEL .1. THE FACE-ON TORUS

Theoretical emission-line profiles are obtained for active galactic nu clei (AGNs) taking into account the presence of an obscuring torus aro und the central energy source. For the sake of simplicity, the torus i s represented by a cylindrical shell characterized by the inner and ou ter radius and the opening angle. In this paper we discuss the results with angle of sight equal to 0, i.e., for a face-on torus. Different line profiles are obtained following the torus parameters. The line pr ofiles may show more than one peak and bumps, depending on the torus d imensions. The main parameter determining the number of peaks or bumps is the opening angle. Thus, the observed line shape may be a good ind icator of the torus characteristics. As an example, the fit to the obs erved [O III] lambda 5007 emission line of NGC 4151 is presented. The model reproduces the FWHM and the asymmetrical bumps observed.