Comparative parameters of Seyfert 1 and Seyfert 2 galaxies

Bolometric luminosities (infrared + optical + x-ray) are calculated for 35 Seyfert 1 and 15 Seyfert 2 galaxies. The parameters of the gas in the nucleus of each galaxy (volume, mass, kinetic energy, characteristic size) are estimated in the zones where the broad wings of the permitted lines (the H II zone) and the forbidden lines (the O III zone) are formed; mean parameters are obtained for each of these emission zones. Type 1 Seyferts differ markedly from type 2's in having an enhanced x-ray luminosity, a bluer color, and perhaps a higher mean bolometric luminosity. The earlier finding that Seyfert 2 galaxies lack an inner zone of relatively dense gas is confirmed. The data obtained here are compared with theoretical models. Type 1 and type 2 Seyferts may differ because of the presence (type 1) or absence (type 2) of an accretion disk around a massive black hole at the center. An alternative but complementary possibility is that Seyfert 1 galaxies are radiating in a near-critical regime (close to the Eddington limit), while Seyfert 2 galaxies may have a luminosity far below the critical value