Which mechanism is named for Roger Blandford and Roman Znajek and can extract energy from a spinning black hole?

The Blandford–Znajek process can extract rotational energy from a spinning black hole through magnetic fields.

Roger Blandford and Roman Znajek proposed the mechanism in 1977. In the model, magnetic fields threading the region around a rotating black hole are twisted by frame dragging. Energy and angular momentum can then be carried outward along electromagnetic fields, potentially powering highly relativistic jets.

The process does not mean that material escapes from inside the event horizon. Instead, the energy comes from the black hole’s rotation and is transferred through electromagnetic interactions outside the horizon. The surrounding accretion flow supplies plasma and helps anchor the magnetic field.

The mechanism is one leading explanation for jets from active galactic nuclei and some systems containing stellar-mass black holes. Its strength depends on the black hole’s spin, the magnetic flux near the horizon, and the structure of the surrounding accretion flow.