One Jet Rule for All Black Holes, From the Smallest to the Largest
Astronomers studying stars torn apart by supermassive black holes have found that the trigger for jet formation is the same fraction of a black hole's maximum feeding rate, about 2%, regardless of how massive the black hole is. The result, published Sept. 17 in Nature Astronomy, supports the idea that a single physical process governs jet launching across all black holes.
Adelle J. Goodwin and Andrew Mummery used tidal disruption events (TDEs), episodes in which a star strays too close to a galactic center and is consumed, as a tool for tracking how supermassive black hole accretion flows change over time. Such events evolve over years, making them the only practical window onto the same kind of accretion state transitions that are well studied in stellar-mass black holes, which cycle through states in weeks.
The paper reports that TDEs produce a second, physically distinct outflow when the accretion rate falls to roughly 2% of the Eddington limit, the rate at which radiation pressure balances gravity. That threshold matches the critical accretion rate at which accreting stellar-mass black holes switch between jet-producing and non-jet-producing states, as observed in X-ray binary systems. The agreement holds across roughly ten orders of magnitude in black hole mass.
Goodwin and Mummery write that the match across such different mass scales "strongly indicates that a single, scale-invariant physical process governs jet launching in all black holes." The paper also provides a framework for predicting which black holes will launch jets and when: a practical tool for planning multi-wavelength follow-up of future TDE detections.
