Analytical and Numerical Methods and Test Calculations of One-dimensional Force-free Magnetodynamics on Arbitrary Magnetic Surfaces across Horizons of Spinning Black Holes

Abstract

Numerical simulations of the force-free magnetodynamics (FFMD) of the electromagnetic field around a spinning black hole are useful to investigate the dynamic electromagnetic processes around a spinning black hole, such as the emergence of the Blandford--Znajek mechanism. To reveal the basic physics of magnetic fields around a black hole through the dynamic process, we use one-dimensional (1D) FFMD along the axisymmetric magnetic surface, which provides a relatively simple, sufficiently precise, and powerful tool to analyze the dynamic process around a spinning black hole. We review the analytic and numerical aspects of 1D FFMD for an arbitrary magnetic surface around a black hole. In addition, we also show some numerical simulation test results for three types of magnetic surfaces at the equatorial plane of the black hole.