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Session 40 - Radiogalaxies & Jets.
Display session, Tuesday, January 14
Motivated by the puzzling, radio-quiet optical jets from the spiral galaxy NGC 1097, we have carried out a search for similar optical jets. The source list was compiled from a visual inspection of all S(E)RC-J sky survey plates at galactic latitudes beyond \pm 10^\circ. Selection criteria were based on a pilot project (Keel 1985 AJ 90, 2207) which compared sky-survey and CCD images of possible jets, resulting in criteria of straightness, relative brightness, and sidedness to rule out tidal features, polar rings, and photographic artifacts. For 113 of the most promising objects, based on comparison with accepted optical jets, we have analyzed CCD imagery from ESO and CTIO to confirm the reality and nature of the apparent jets. Depending on the galaxy structure, we used spatial filtering, flip-and-subtract, or image modelling to remove the overall galaxy structure. Of this sample, eight objects show a radial, linear feature which is faint enough compared to the galaxy to be a plausible jet candidate (instead of a companion or tidal feature). A single one of these, the Sab component of AM 0410-421 at z=0.06066, has a catalogued redshift, showing both galaxy and jet to have luminosities comparable to the values for M87. The search probably would have recovered NGC 1097 itself, based on its jets' appearance on the survey plates, while objects like M87 and PKS 0521-36 would have been missed to photographic saturation of the inner parts of these galaxies. From these results, there may indeed be a rare class of optically-detectable but radio-quiet features which plausibly result from nuclear ejection.
Program listing for Tuesday