Magnetic Hair and Reconnection in Black Hole Magnetospheres

The no-hair theorem of general relativity states that isolated black holes are characterized by three parameters: mass, spin, and charge. In this Letter we consider Kerr black holes endowed with highly magnetized plasma-filled magnetospheres. Using general relativistic kinetic plasma and resistive magnetohydrodynamics simulations, we show that a dipole magnetic field on the event horizon opens into a split monopole and reconnects in a plasmoid-unstable current sheet. The no-hair theorem is satisfied, in the sense that all components of the stress-energy tensor decay exponentially in time. We measure the decay time of magnetic flux on the event horizon for plasmoid-dominated reconnection in collisionless and collisional plasma. The reconnecting magnetosphere should be a powerful source of hard x-ray emission when the magnetic field is strong.

Automated summary

This passage discusses the no-hair theorem of general relativity, outlining the characteristics of isolated black holes and their interaction with highly magnetized plasma-filled magnetospheres. It describes the behavior of dipole magnetic fields on the event horizon of Kerr black holes, as well as the reconnection process in plasmoid-unstable current sheets. Additionally, it highlights the potential for strong magnetic fields in the reconnecting magnetosphere to emit hard x-ray radiation.