Particle acceleration in relativistic current sheets.

Relativistic current sheets have been proposed as the sites of dissipation in pulsar winds, jets in active galaxies, and other Poynting flux dominated flows. It is shown that the steady versions of these structures differ from their nonrelativistic counterparts because they do not permit transformation to a de Hofmann-Teller frame with zero electric field. Instead, their generic form is that of a true neutral sheet with no linking magnetic field component normal to the sheet. The maximum energy to which such structures can accelerate particles is derived, and used to compute the maximum frequency of the subsequent synchrotron radiation. This can be substantially in excess of standard estimates. In the magnetically driven gamma-ray burst scenario, acceleration of electrons is possible to energies sufficient to enable photon-photon pair production after an inverse Compton scattering event.