Black holes of every size follow the same surprising rule

Scientists have found evidence that black holes of vastly different sizes may launch powerful jets according to the same universal rule. Supermassive black holes can produce jets soon after tearing apart a star, then fire up again hundreds or thousands of days later when their feeding rate drops to about 2% of the Eddington limit. That same threshold is known to trigger jets from much smaller black holes in the Milky Way.