A STUDY OF THE STRUCTURE AND KINEMATICS OF THE NARROW-LINE REGION IN SEYFERT-GALAXIES .3. INDIVIDUAL OBJECTS

This is the third paper in a series discussing the results of a high-resolution study of the narrow-line profiles in 16 Seyfert galaxies. In this paper the objects in the sample are analyzed individually. The high spectral resolution, excellent signal-to-noise ratio, and broad wavelength coverage of the data allow a detailed comparison of the emission-line profiles in each galaxy through profile ratio and decomposition techniques. Substructure is observed in the narrow-line profiles of all but one of the objects in the sample (Mrk 359). A direct relationship between the radio structure and these emission-line components appears to exist in at least six objects. Evidence for ionization/density stratification of the gas in the narrow-line region (NLR) was discovered or confirmed in 4 (ionization)/5 (density) of the 11 objects in the sample for which a multispecies analysis was possible. Stronger evidence for stratification is observed in the objects whose emission lines present a minimum of profile substructure. The results of profile ratios suggest that the blueward asymmetry, observed in the profiles of at least 10 of the 16 galaxies in the sample, is caused by dust within the line-emitting clouds or by the effects of an occulting (i.e., highly optically thick) component located near the nucleus. The gas producing the blue wing generally is more highly ionized than the rest of the gas. A multicomponent model of the NLR is proposed to attempt to tie together the results of Papers I, II, and III and of previous kinematic studies.