Black Holes of All Sizes Emit Jets at a Common 2% Eddington Threshold

Scientists have shown that black holes, whether supermassive or stellar‑mass, launch powerful jets when their feeding rate falls to roughly 2 % of the Eddington limit. In supermassive black holes, the jets appear shortly after a star is torn apart, then flare again hundreds or thousands of days later as the accretion rate drops. The same 2 % threshold also triggers jet production in smaller black holes within the Milky Way. The discovery links jet activity across a vast range of masses, suggesting a universal mechanism that governs how black holes convert accreted matter into relativistic outflows. This insight refines models of black hole growth and feedback, and may help explain the diverse jet phenomena observed in active galactic nuclei and X‑ray binaries alike.