Name of the Speaker(s): Pariev Vladimir
Institution: Radioastromomy Department of P.N.Lebedev Physical Institute (Russia)
Title of the communication: Stability of a relativistic rotating electron-positron jet and superluminal motion of knots.
Preliminary abstract (12 lines max.): The linear stability of a hydrodynamic relativistic flow of magnetized plasma is investigated in force-free approximation. Numerical calculations showed that modes having reasonable values of azimuthal wavenumber $m$ and radial number $n$ are stable and have attenuation increment $\gamma$ small. The dispersion curves $\omega =\omega (k_\parallel)$ have a minimum for $k_{{\parallel}_0}\simeq 1/R$ ($R$ is the jet radius ). This results in accumulation of perturbations inside the jet with wavelength of the order of the jet radius. The wave crests of the perturbation pattern formed in such a way move along the jet with the velocity exceeding light speed. If one has relativistic electrons emitting synchrotron radiation inside the jet, than this pattern will be visible. This provide us with the new type of superluminal source. If the jet is oriented close to the line of sight, than the observer will see knots moving backward to the core.