The physics of jets in FR I radio galaxies
  We model jets in low-luminosity (FR I) radio galaxies as intrinsically symmetrical, axisymmetric, decelerating relativistic flows with transverse velocity gradients. This allows us to derive velocity fields and the three-dimensional distributions of magnetic-field ordering and rest-frame emissivity. A conservation-law analysis, combining the kinematic model with X-ray observations of the surrounding IGM, gives the profiles of internal density, pressure, Mach number and entrainment rate along the jets. We summarize our recently-published results on 3C 31 and outline new work on other sources and adiabatic jet models. 
R. A. Laing (1 and 2), J.R. Canvin (1), A.H. Bridle (3) ((1) Oxford,   (2) RAL, (3) NRAO)