# Towards a Full MHD Jet Model of Spinning Black Holes--I: Framework and a split monopole example

## TL;DR

This paper develops a comprehensive framework for modeling magnetohydrodynamical jets from spinning black holes, solving coupled equations numerically for specific magnetic configurations, and explores energy extraction mechanisms like the magnetic Penrose process.

## Contribution

It introduces a self-consistent numerical approach to solve MHD jet equations for spinning black holes, including a split monopole example and analysis of energy extraction processes.

## Key findings

- Magnetic field lines are dragged by fluid inertia.
- Fluid alone does not extract energy from the black hole.
- Magnetic Penrose process can operate for charged components at low plasma loading.

## Abstract

In this paper, we construct a framework for investigating magnetohydrodynamical jet structure of spinning black holes (BHs), where electromagnetic fields and fluid motion are governed by the Grad-Shafranov equation and the Bernoulli equation, respectively. Assuming steady and axisymmetric jet structure, we can self-consistently obtain electromagnetic fields, fluid energy density and velocity within the jet, given proper plasma loading and boundary conditions. Specifically, we structure the two coupled governing equations as two eigenvalue problems, and develop full numerical techniques for solving them. As an example, we explicitly solve the governing equations for the split monopole magnetic field configuration and simplified plasma loading on the stagnation surface where the poloidal fluid velocity vanishes. As expected, we find the rotation of magnetic field lines is dragged down by fluid inertia, and the fluid as a whole does not contribute to energy extraction from the central BH, i.e., the magnetic Penrose process is not working. However, if we decompose the charged fluid as two oppositely charged components, we find the magnetic Penrose process does work for one of the two components when the plasma loading is low enough.