Magnetohydrodynamic models for extragalactic jets. I - General method based on conservation laws

Abstract A general method for building up composite magnetic and flow model structure for the description of jets is introduced. The method is essentially based on the use of MHD conservation equations to construct a steplike model in which the jet is represented as a sequence of purely cylindrical segments whose physical properties are related through the conservation laws. The method is applied to the study of the magnetic structure in a region near the end of the large-scale jet. Polarization distributions predicted by the model indicate that changing the magnetic configuration along the jet allows reproduction of FR I jet polarization features without involving highly wound-up helical fields.