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We performed one-dimensional force-free magnetodynamic numerical simulations of the propagation of Alfven waves along magnetic field lines around a spinning black-hole-like object, the Banados--Teitelboim--Zanelli black string, to investigate the dynamic process of wave propagation and energy transport with Alfven waves. We considered axisymmetric and stationary magnetosphere and perturbed the background magnetosphere to obtain the linear wave equation for the Alfven wave mode. The numerical results show that the energy of Alfven waves monotonically increases as the waves propagate outwardly along the rotating curved magnetic field line around the ergosphere, where energy seems not to be conserved, in the case of energy extraction from the black string by the Blandford--Znajek mechanism. The apparent breakdown of energy conservation suggests the existence of an additional wave induced by the Alfven wave. Considering the additional fast magnetosonic wave induced by the Alfven wave, the energy conservation is recovered. Similar relativistic phenomena, such as the amplification of Alfven waves and induction of fast magnetosonic waves, are expected around a spinning black hole.
We consider the evolution of a cosmic string loop that is captured by a much more massive and compact black hole. We show that after several reconnections that produce ejections of smaller loops, the loop that remains bound to the black hole moves on
In this note we observe that the exact Maxwell-Einstein equations in the background metric of a spinning string can be solved analytically. This allows us to construct an analytical model for the magnetosphere which is approximately force free near t
In this letter, we present the first 3D force-free general relativity simulations of the magnetosphere dynamics related to the magnetar outburst/flare phenomenology. Starting from an initial dipole configuration, we adiabatically increase the helicit
We investigate a vacuum decay around a spinning seed black hole by using the Israel junction condition and conclude that the spin of black hole would suppress a vacuum decay rate compared to that for a non-spinning case, provided that the surface of
In this work, expanded solutions of force-free magnetospheres on general Kerr black holes are derived through a radial distance expansion method. From the regular conditions both at the horizon and at spatial infinity, two previously known asymptotic