A black hole accretes matter. The infalling material releases gravitational potential energy, some fraction of which powers jets — collimated outflows of magnetized plasma moving at nearly the speed of light. In the standard picture, the jet power is limited by the accretion power: you can't get more energy out of the jet than the matter brings in. The efficiency — jet power divided by accretion power — is typically a few percent, rising to perhaps tens of percent in favorable configurations.
Nathanail (arXiv 2602.22824, February 2026) demonstrates jet efficiencies exceeding 100 — the jet power is more than a hundred times the power supplied by accretion. The jet is not powered by the infalling matter.
The energy source is the black hole's rotation. The Blandford-Znajek mechanism extracts rotational energy from a spinning black hole through magnetic field lines threading the event horizon. When the magnetic field is strong enough to saturate — the magnetically arrested disk (MAD) state — the field pressure near the horizon balances the ram pressure of the infalling gas, periodically halting or reversing accretion. In this state, the hole's spin energy is extracted more efficiently than matter energy is deposited.
The simulation achieves a quasi-steady MAD state sustained for approximately 10,000 dynamical times — far longer than previous simulations. During this period, accretion is globally suppressed across the entire azimuthal extent of the disk. The magnetic field, however, remains anchored to the horizon and continues extracting spin energy. The result is a regime where the denominator (accretion power) drops while the numerator (jet power from spin extraction) remains high. The efficiency ratio diverges not because the jet got stronger, but because the accretion got weaker.
This isn't violating energy conservation. The total energy budget includes the black hole's rotational energy, which for a maximally spinning hole can be up to 29% of its rest mass — an enormous reservoir. The Blandford-Znajek process taps this reservoir through the magnetic field, converting spin energy to Poynting flux in the jet. The process slows the hole's rotation, and the jet carries away the difference.
The observational implication: jets observed to be far more powerful than their host accretion flows would suggest are not anomalous. They are not over-powered. They are spin-powered, operating in a regime where the black hole itself is the fuel.