3C 390.3: Modeling Variable Profile Humps

Abstract

A comparison of the Hα and Hβ profiles of the radio galaxy 3C 390.3 at different epochs shows that the Hβ/Hα ratio is significantly higher in the line "humps" than in the rest of the profiles. No humps are found in the Lyα profile, although Lyα is as broad as the Balmer lines. Therefore, the profile humps are probably produced in a region of higher density. A double-stream model fitted to the Hα profiles requires that the conical structure is close to the line of sight and subtends a large angle (>=60^deg^) and a limited radial distance (R_max_/R_min_ <= 10). The pair of humps in the profile may arise from gas lumps or a narrow stream inside the cone. Fluctuations in the blue-to-red hump flux ratio may be due to variations in the relative intensity of the ionizing continuum in the two cones or to changes in the orientation of these cones. Another model is a disk with a corotating enhanced emission region ("hot patch"). With a significant angular size (~90^deg^), such a region would contribute a time-dependent emission component which migrates between the two humps and changes their relative intensity.