From many studies we understand the main features of Seyfert galaxy spectra as resulting from photoionization by a spectrum that extends to high-energy photons. In this model, both the ionizing photons and the radio plasma can escape through the BLG most easily along the axis of the cylinder, where the amount of material encountered is the smallest, and correspondingly the ionized NLG has a roughly conical distribution about this axis. Intermediate objects in the classification scheme are those which have intermediate amounts of BLG, according to this model. Schematic observational model of an AGN as described in text.
Ionized gas is shown in various cross-hatchings as indicated, neutral gas is shown as plain white.
Furthermore, there are many indications that the active galactic nucleus may be tipped with respect to the main body of the galaxy in which it occurs. The small cylindrically symmetric. The core about the axis of the BLR, in which most of the ionizing photons that get to the NLR escape, is shown by the dashed lines, and the units of the structure implied by the small filling factor are schematically indicated as spherical, homogeneous, uniform-density clouds. Schematic, slightly more sophisticated observational model of an AGN as described in text. Tilt of BLR with respect to NLR, and ionization structure of clouds in NLR are indicated.