Magnetic Field Structure

If the coherence length of the magnetic field is larger than the gyroradius of particles, the structure of the magnetic field in the dissipation region does not affect the spectrum or the pulse profile. However, it significantly affects the level of polarization. Therefore, spectro-polarimetric observations that strongly indicate synchrotron emission as the underlying radiation mechanism can be used to also determine the magnetic field structure. At least four physically motivated axisymmetric magnetic field structures, and the emergent synchrotron polarization, have been discussed in the literature [108–111]:


as the flow expands. Therefore, at large distances from the central engine the toroidal field component dominates.
