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• The Collimation of Relativistic Jets in Quasars,
  K. I. Kellermann, D. C. Homan, M. L. Lister, M. H. Cohen, R. C. Vermeulen, E. Ros, J. A. Zensus;
  IAU XXV General Assembly, Joint Discussion 18, Quasar Cores & Jets, Sydney, Australia, July 23, 2003
  
  • Abstract High resolution radio interferometry provides a unique opportunity to directly study the formation and evolution of relativistic jets associated with accretion onto massive black holes in quasars and AGN. Since 1994 we have been using the NRAO Very Long Baseline Array to study the collimation and motions of the relativistic jets which flow outward from quasar cores. Most quasars show apparent superluminal velocity with apparent speeds ranging up to about 30c. The motion of individual features is often non-linear reflecting apparent complex three dimensional trajectories. However, a detailed quantitative analysis is difficult, owing to poorly defined moving features which may brighten and fade with time, apparent differences between the bulk motion of the relativistic flow and the apparent pattern (shock) speed, as well as to the unknown distribution of intrinsic Lorentz factors. Each jet appears to have a preferred position angle which sometimes extends hundreds of thousands of kpc from the core, but the focusing of the jet along this trajectory may occur up to a kpc or more downstream from the core. Observations now in progress will extend these studies to include changes in linear and circular polarization in a well-defined complete sample of quasars and AGN.

Eduardo Ros ros@mpifr-bonn.mpg.de

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