Connections between Turbulence and Jet Morphology
Radio jet morphologies may be caused by large-scale Kelvin-Helmholtz (KH) instabilities. If high-speed, pressure-confined fluid beams lie at the core of these jets, they are susceptible to KH modes, as studied by a number of authors.1–5 The “wiggles” seen, for example, in 3C449, NGC 6251, M87 and Cen A, may arise from helical instabilities. 3–4 “Knots” may be radial oscillations (not necessarily unstable) forming sausage-like regions of compression, as in NGC 315, M87, Cen A etc. There seems no reason why such macroscopic modes should not appear. The smaller scale waves, however, cannot be easily resolved by radio astronomy, and can have profound effects, such as particle reacceleration. It would be rather more satisfying if there were observable large-scale implications of the microturbulence.