Previous abstract Next abstract
We have imaged 13 extended 3CR quasars with high sensitivity and resolution using the VLA at 4.9 GHz.
We find a strong correlation between the prominence (relative to the extended lobe emission) of the milli-arc-second scale central features and of the inner, straight segments of the radio jets. The outer, bent, jet segments do not share this correlation, however.
Jet bending favors the detection of counterjet candidates, and inhibits the formation of prominent hot spots. There are no counterjet candidates opposite long, uninterrupted straight segments of the jets, and there is no evidence that the prominence of counterjet candidates anti-correlates with that of the jets, as it would if relativistic beaming controls the jet/counterjet asymmetry far from the quasar.
These data favor ``tired jet'' models in which the flows through the parsec-scale radio features are highly relativistic but those in larger-scale jets are only mildly relativistic. Further decreases in average jet velocity on kiloparsec scales may then (a) allow the jets to bend, (b) allow counterjets to become more visible, and (c) reduce the jets' ability to form compact hot spots.
We find a further correlation that may conflict with the simplest tired-jet interpretation, however. When there is a strong asymmetry in compactness between the jetted and counterjetted hot spots, it is always the jetted spot that is more compact. The hot spots thus retain some memory of the jet-sidedness asymmetry, but the mechanism for this is not clear.
Friday program listing