Highly-collimated, magnetically-dominated jets around rotating black holes

Understand

In this paper, we propose a general method for perturtative solutions to Blandford-Znajek mechanism.

• Instead of solving the nonlinear Grad-Shafranov equation directly, we introduce an alternative way to determine relevant physical quantities based on the horizon boundary condition and the convergence requirement.
• Both the angular velocity $\Omega$ of magnetic field lines, the toroidal magnetic field $B^\phi$ and the total electric current $I$ are self-consistently specified according to our method.
• As an example, stationary axisymmetric and force-free jet models around rotating black holes are self-consistently constructed according to the method we proposed.