Self-collimation and magnetic field generation of astrophysical jets

A novel model for collimation and transport of electron-positron-ion jets is presented. Analytical results show that the filamentary structures can be sustained by self-induced toroidal magnetic fields permeating through the filaments, whose widths significantly expand in the pair-dominant regimes. The magnetic field strength reflects a characteristic of equipartition of excess kinetic energy of the jets. It is also shown that growth of the hoselike instability is strongly suppressed. Essential features derived from this model are consistent with recent results observed by using very long baseline telescopes.