On the Coupling of Rotation Powered Pulsars to Plerionic Nebulae

After discussion of observational constraints on the nature of the MHD wind coupling between the Crab Pulsar and the Crab Nebula, the theory of transverse relativistic shock structure is reviewed and applied to the interpretation of the wisps in the Nebula as the manifestation of the distributed wind termination shock structure, energetically dominated by heavy ions, accelerated in the rotational equator of the pulsar to energies comparable to the total voltage across the pulsar's open field lines and carrying a current comparable to the Goldreich- Julian current. New results on the variability of the shock structure are presented, which show that the gyrating ion bunches emit outwardly traveling finite amplitude compressional waves, in agreement with recent ground based observations. The implications of the theory for X-ray, $\gamma$-ray and high energy neutrino emission are briefly discussed, as are the problems of low magnetic energy density in the upstream wind and the origin of the Nebular radio emission. A brief discussion of other plerions leads to the conclusion that much more detailed observations are needed before these systems can be modeled with the same sophistication as can be done for the Crab Nebula.