Perucho, Manel

Jet dynamics and stability.

In my talk, I will review our recent results on the effects of the growth of instabilities on jet structure and evolution of relativistic jets. The analysis of VLBI observations of the jet in 0836+710 shows that theobserved helical structure of the jet responds to a pattern motion,possibly related to a pressure maximum within the jet cross-sectiondriving the helical motion. I will discuss some implications that thisresult has with respect to the long-term evolution of this jet, and moregenerally, regarding the nature of the radio core and the superluminaltransversal motions detected in other extragalactic jets. I will alsopresent results from a detailed study of a strong flare in CTA 102. We have followed the spectral and kinematic evolution of the injected perturbation in the jet and obtained possible evidence for shock-shock interaction, possibly produced by the travelling perturbation and a standing shock within the core region.