Numerical simulation of magnetic reconnection around a black hole

TL;DR

This paper uses numerical simulations to study magnetic reconnection near a Schwarzschild black hole, revealing its characteristics, rate dependence on resistivity, and agreement with theoretical models.

Contribution

First to simulate relativistic magnetic reconnection around a black hole with resistivity, showing reconnection dynamics and rate behavior consistent with theoretical models.

Findings

Reconnection occurs near the black hole's equatorial plane.

Reconnection rate decreases with smaller resistivity.

Reconnection rate increases linearly over time for high magnetic Reynolds numbers.

Abstract

We performed numerical simulations of general relativistic magnetohydrodynamics with uniform resistivity to investigatethe occurrence of magnetic reconnection in a split-monopole magnetic field around a Schwarzschild black hole. We found that magnetic reconnection happens near the black hole at its equatorial plane. The magnetic reconnection has a point-like reconnection region and slow shock waves, as in the Petschek reconnection model. The magnetic reconnection rate decreases as the resistivity becomes smaller. When the global magnetic Reynolds number is $10^4$ or larger, the magnetic reconnection rate increases linearly with time from $2 \tau_{\rm S}$ to $\sim 10 \tau_{\rm S}$ ($\tau_{\rm S}=r_{\rm S}/c, r_{\rm S}$ is the Schwarzschild radius and $c$ is the speed of light). The linear increase of the reconnection rate agrees with the magnetic reconnection in the Rutherford regime of the tearing mode instability.