The Physics of E X B-drifting Jets

E x B-drifting jets have been generally ignored for the past 25 years even though they may well describe all the astrophysical jet sources, both on galactic and stellar scales. Here we present closed-form solutions for their joint field-and-particle distribution, argue that the observed jets are near equipartition, with extremely relativistic, mono-energetic e ±-pairs of bulk Lorentz factor γ < ∼ 10 4 , and are first-order stable. We describe plausible mechanisms for the jets' (i) formation, (ii) propagation, and (iii) termination. Wherever a beam meets with resistance, its frozen-in Poynting flux transforms the delta-shaped energy distribution of the pairs into an almost white power law, E 2 N E ∼ E −ǫ with ǫ > ∼ 0, via single-step falls through the convected potential. 1. How much is known? Pair-plasma jets with ultra-relativistic bulk motion have been proposed twenty-five years ago by one of us (Kundt, 1979), then jointly elaborated by us (Kundt & Gopal-Krishna, 1980). They were also proposed by Morrison (1981), but have usually not been mentioned (cf. A possible reason for this lack of widespread acceptance may have been a concern about whether or not the beams allowed a stable transport of a broad energy distribution of high-energy charges, in the form of an ordered E x B-drift. The beams are indeed unlikely to transport a broad distribution. Instead, their Poynting-flux-flooded formation regions are expected to generate particle distributions at least as sharp in 4-momentum as relativistic Maxwellians, and an onsetting E x B-drift will further sharpen the narrow distribution towards a delta-type one. Such equipartition pair-plasma flows convect half of their energy as a stationary Poynting flux which is ready – wherever stalled – to broaden the particle distribution into an almost white power law, starting with Lorentz factors of order 10 2 at their bottom end, and extending up to Lorentz factors of order 10 6 , in the form of a long high-energy tail 1