Towards a Full MHD Jet Model of Spinning Black Holes

The Event Horizon Telescope has achieved resolution of ~ 60 microseconds on 1.3 mm wavelength, which has been used for resolving the horizon-scale structure of black holes (BHs) nearby, including Sgr A* and M87. Motivated by the coming high-resolution observations, we aim to develop a full MHD jet model of spinning BHs. In this model, 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 boundary conditions and plasma loading. As an example, we explicitly solve the two governing equations for the split monopole magnetic field configuration and a 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.

Zhen Pan (Perimeter Institute)
DoA, Rm 2907
Mon, 2018-12-17 12:00 to 13:00