SwePub - search: WFRF:(Hardee Philip)

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1.	Perucho, Manel, et al. (author) VLBI observations of helical jets: Hints on the nature of radio-jets 2012 In: Proceedings of Science. - 1824-8039. ; 2012-October Conference paper (peer-reviewed)abstract We make use of VLBI observations of the radio jet in the quasar S5 0836+710 at different frequencies and epochs to study its properties. The jet shows helical structure at all frequencies. The ridge-line of the emission in the jet coincides at all frequencies and epochs, within the errors. We conclude that the helicity is a real, physical structure. Small differences between epochs reveal wave-like motion of the ridge-line transversal to the jet propagation axis. These transversal motions are measured to be superluminal. This unphysical result could correspond to a possible small amplitude oscillation of the ridge-line at the radio-core and to large errors in the determination of the positions. In addition, higher resolution images at 15 GHz show that the ridge-line does not coincide exactly with the centre of the radio jet. At arc-second scales, this powerful jet shows non-collimated, irregular structure and a lack of a hot-spot. Following this collection of evidence, we conclude that the ridge-line could be related to a pressure maximum within the jet cross-section, associated with the observed helical pattern that could lead to jet disruption at longer scales.

Perucho, Manel, et al. (author)
VLBI observations of helical jets: Hints on the nature of radio-jets
2012
In: Proceedings of Science. - 1824-8039. ; 2012-October
Conference paper (peer-reviewed)abstract
- We make use of VLBI observations of the radio jet in the quasar S5 0836+710 at different frequencies and epochs to study its properties. The jet shows helical structure at all frequencies. The ridge-line of the emission in the jet coincides at all frequencies and epochs, within the errors. We conclude that the helicity is a real, physical structure. Small differences between epochs reveal wave-like motion of the ridge-line transversal to the jet propagation axis. These transversal motions are measured to be superluminal. This unphysical result could correspond to a possible small amplitude oscillation of the ridge-line at the radio-core and to large errors in the determination of the positions. In addition, higher resolution images at 15 GHz show that the ridge-line does not coincide exactly with the centre of the radio jet. At arc-second scales, this powerful jet shows non-collimated, irregular structure and a lack of a hot-spot. Following this collection of evidence, we conclude that the ridge-line could be related to a pressure maximum within the jet cross-section, associated with the observed helical pattern that could lead to jet disruption at longer scales.

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