⚫ Black holes launch their jets at the same threshold, regardless of their size
Astronomers have discovered that black holes of varying sizes begin emitting jets of matter at a consistent threshold of 2% of the Eddington limit. This finding was made by observing stellar disruptions, which provide a clearer timeline for matter emission than supermassive black hole feeding cycles.
Why it matters
This discovery provides a universal benchmark for understanding how black holes interact with surrounding matter, regardless of their scale.
A black hole can attract gas around it. This matter generally does not fall directly in: it forms a disk, heats up and gradually loses energy before moving closer. Some of it may also return to space in the form of jets or other fast outflows. But the moment when these emissions appear remained difficult to predict for giant black holes.
The problem mainly comes down to time. Around the supermassive black holes at the centers of galaxies, feeding can continue for thousands of years. Astronomers therefore studied brief events: the destruction of a star passing too close to a black hole.
Artist’s view of a star stretched and torn apart by the tidal forces of a supermassive black hole. Credit: ESO/M. Kornmesser
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