MAGNETIC-STRUCTURE OF PULSAR WINDS

The expectation has long been that pulsar winds (with extension to ste llar winds is some cases) are energetically dominated by their magneti c fields. Coroniti has recently argued that reconnection could transfe r energy from magnetic reversals in the wind into particle energy. Thi s process could have observational consequences in binary systems such as PSR 1957 + 20 because the wind properties could change before inte racting with the companion. We show here that the reconnection process is simply inductive heating, which allows it to be calculated without appeal to existing phenomenology surrounding reconnection. Surprising ly, we find that the resultant wind will not necessarily shock, becaus e it is not super-Alfvenic, but rather may simply decelerate smoothly to match nebular boundary conditions. Moreover, the two oppositely mag netized hemispheres are not causally disconnected, and the flow should then relax meridionally which should lead to formation of an equatori al neutral sheet. Such a neutral sheet will not dissipate the field in ductively (unlike the sheets perpendicular to the flow), but may indee d be unstable to reconnection. A rather simple picture for magnetizati on of the wind emerges in which plasma is ''frozen'' into the large-am plitude electromagnetic waves generated by the orthogonal magnetic dip ole component of a rotating magnetic (neutron) star. As the plasma is convected away, it also pulls with it the aligned dipole magnetic fiel d lines beyond the wind zone (''light cylinder''). At large distances from the star, the wave component is dissipated, leaving behind the wo und-up field lines of the aligned component. It will be important to e xplore the torques exerted by these two components to eventually under stand why pulsar magnetic fields do not seem to asymptotically achieve either alignment parallel or orthogonal to the spin axis.