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K. Brecher (Boston University)
The actual mechanism for acceleration of pulsars to high (500 km/sec) spatial velocities is not definitively known. Intrinsically asymmetric supernova explosions or disruption of binary star systems are possible causes. Asymmetric emission of magnetic dipole radiation, nonthermal electromagnetic radiation and/or energetic particles arising from off-center neutron star dipole magnetic fields has also been proposed as a possible cause (Harrison & Tademaru, Ap. J., 201, 447, 1975). However, to be effective, this mechanism requires high magnetic fields and/or rapid rotation. Strong magnetic field neutron stars (dubbed “magnetars”) have been proposed to be the underlying causes of the soft gamma-ray repeaters (Duncan & Thompson, Ap. J., 392, L9, 1992). We have re-examined models for the early evolution of pulsar magnetic fields and radiation. A plausible range of initial and evolutionary parameters can lead to high pulsar proper motions. Therefore, the Harrison-Tademaru mechanism could be responsible for the acceleration of neutron stars to the high velocities associated with soft gamma-ray repeaters such as the March 5, 1979 source in the supernova remnant N49 in the LMC.
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