On the internal structure of relativistic jets

A magnetohydrodynamic model is constructed for a cylindrical jet embedded in an external uniform magnetic field. It is shown that, as in the force-free case, the total electric current within the jet can be zero. The particle energetics and the magnetic-field structure are determined in a self-consistent way; all jet parameters depend markedly on the physical conditions in the external medium. In particular, we show that a region with subsonic flow can exist in the central jet regions. In real relativistic jets, most of the energy is transferred by the electromagnetic field only at a sufficiently large magnetization parameter sigma > 10(6). We also show that, in general, the well-known solution with a central core B-z = B-0/(1 + omega(2)/omega(c)(2)) cannot be realized in the presence of an external medium. (C) 2000 MAIK Nauka/Interperiodica.