New force-free magnetospheres in the Schwarzschild spacetime

Abstract

The force-free condition is a widely used approximation in magnetospheric physics, particularly in the study of strongly magnetized astrophysical objects such as pulsars and relativistic black~hole jets. We propose a novel solution-generating method to force-free electrodynamics from simple solutions in arbitrary spacetime with the aid of exterior calculus. Then, we apply this method to find dynamic magnetospheres in Schwarzschild background. We find nonradiative solutions and radiative solutions with Poynting fluxes that scale similarly as ~tr in large distances at finite time. These solutions can serve as zeroth-order fields to plasma-filled force-free magnetosphere surrounding a rotating black hole or pulsar.