Wiggles and knots in radio jets

Dynamical effects in binary nuclei inside parent galactic cores, gravitational interactions with companion galaxies and Kelvin-Helmholtz instabilities in the flow propagation have been proposed as mechanisms responsible for the formation of the low amplitude morphologies, wiggles and knots, observed in radio jets. The authors discuss the basic characteristics and implications of these models, and confront them with the limited number of existing data. In conclusion they show that present observations cannot discriminate definitely between these theories; conversely, different mechanisms may be at work together in any jet at the same time. (Auth.)