The narrow line region of active galaxies - III. Profile comparisons.

High-dispersion observations of different narrow emission line profiles are presented for a sample of nine galaxies. Some causes of profile differences are examined, including velocity gradients and line ratio gradients. The observations were combined with previous profile observations to give a total sample of 23 active galaxies, comprising eight Seyfert 2s; five Seyfert 1s; nine intermediate Seyferts; and one LINER. A parameter Sigma is defined which characterizes the degree of forbidden profile width difference within each object. A strong correlation between Sigma and the strength of the broad line region was found. Correlations between FWHM and the critical density, N_c, and ionization potential X, were also analyzed, and the results are discussed. It is shown that the correlations with N_c tended to be stronger than those with X, suggesting that N_c is a more fundamental parameter. However, the forbidden line of O III was broader than the forbidden line of O I at 6300 A, indicating the opposite trend. A complete list of the emission line galaxies is given.