Helical strands in the jetlike narrow-line region of ESO 428-G14

We present HST/WFPC2 images of the narrow-line region (NLR) of the Seyfert 2 galaxy ESO 428-G14 (0714-2914, M4-1). The NLR consists of many individual, thin strands, which are very closely related to the radio jet and produce a highly complex, yet ordered, structure. We find that the jet is two-sided, with a double helix of emission-line gas apparently wrapped around the northwest side. To the southeast, the jet seems to be deflected at a ridge of highly excited gas. The strands to the southeast may also wrap around the radio jet, but here complete helices are not seen. The overall structure is reminiscent of the jet seen in NGC 4258. Faint symmetric features aligned with the nucleus could indicate the presence of a highly collimated beam of photons or plasma from the center.