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The role of the ergosphere in the Blandford–Znajek process


E-mail: (MR); (CP); (FG); (CB)


The Blandford–Znajek process, one of the most promising models for powering relativistic jets from black holes, was initially introduced as a mechanism in which the magnetic fields extract energy from a rotating black hole. We study the evolution of force-free electromagnetic fields, which are generated by rapidly rotating stars, on regular space–times with an ergosphere. Our conclusive results confirm previous works, claiming that the Blandford–Znajek mechanism is not directly related to the horizon of the black hole. We also show that the radiated energy depends exponentially on the compactness of the star.