AAS Meeting #194 - Chicago, Illinois, May/June 1999
Session 29. White Dwarfs, Neutron Stars and Pulsars
Oral, Monday, May 31, 1999, 2:00-3:30pm, International Ballroom North

## [29.06] The Exact Axisymmetric Pulsar Magnetosphere

D. Kazanas (NASA/GSFC), J. Contopoulos (Un. of Crete), C. Fendt (Astrophysicalishes Institut, Potsdam)

We present, for the first time, the structure of the axisymmetric force--free magnetosphere of an aligned rotating magnetic dipole, in the case in which there exists a sufficiently large charge density (whose origin we do not question) to satisfy the ideal MHD condition, E\cdot B=0, everywhere. The unique distribution of electric current along the open magnetic field lines which is required for the solution to be continuous and smooth is obtained numerically. With the geometry of the field lines thus determined we compute the dynamics of the associated MHD wind. The main result is that the relativistic outflow contained in the magnetosphere is not accelerated to extremely relativistic energies near the light cylinder and therefore it is unlikely that gamma ray production is associated with this location. We expect that our solution will be useful as the starting point for detailed studies of pulsar magnetospheres under more general conditions, namely when either the force-free and/or the ideal MHD condition E\cdot B=0 are not valid in the entire magnetosphere. Based on our solution, we consider that the most likely positions of such an occurrence are the polar cap, the crossings of the zero space charge surface by open field lines, and the return current boundary, but {\em not} the light cylinder.

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