Key points are not available for this paper at this time.
We report high-resolution (0. 1") observations of the Seyfert 2 galaxy NGC 5728 with the Hubble Space Telescope. Images have been obtained in the light of O III λλ4959, 5007, Hα+N II λλ6548, 6583 and green and red continua. The emission-line images reveal a spectacular biconical structure with overall extent 1. 8 kpc. The two cones share a common axis and apex. The cones' axis coincides to within ~3ᵈeg^ with that of the one-sided nuclear radio continuum emission but is not aligned with the rotation axis of the galaxy disk. No O III and only weak Hα + N II emissions are seen at the apex itself where the continuum is also weak and its color red. These results suggest our line of sight to the cones' apex is obscured or blocked. The apex almost certainly reflects the location of the "true" active nucleus, for it coincides with the radio nucleus, the gaseous kinematical center, and the geometrical center of the circumnuclear star-forming ring (which has been interpreted in terms of an inner Lindblad resonance). Bright, barlike features are seen in continuum light and may represent either a kpc-scale stellar bar or scattered nuclear light. Our data provide strong support for unified models of Seyfert galaxies, in which Seyfert 2 nuclei are blocked from direct view by an optically thick torus or other structure, with optical and ultraviolet radiation escaping preferentially along and around the torus axis.
Wilson et al. (Wed,) studied this question.