Black Holes of All Sizes Launch Jets at the Same Critical Feeding Rate

Astronomers observing supermassive black holes shredding stars have documented two seemingly incompatible behaviors. One set of observations shows these cosmic giants blasting out powerful radio jets immediately after tearing a star apart, driven by an extreme influx of stellar material. Another set of data reveals black holes that remain entirely dormant during the initial feast, only to suddenly fire up their jets up to 1,000 days later for no obvious reason. The conflicting timelines made it difficult to determine whether supermassive black holes follow a predictable mechanism or if their delayed eruptions are driven by entirely different physics than their smaller, stellar-mass counterparts.

On September 17, 2026, an international team led by researchers at the Institute for Advanced Study and Curtin University published a study in Nature Astronomy that reconciles these two timelines into a single, universal rule. By analyzing multi-wavelength data from telescopes across four countries—the United States, Australia, India, and South Africa—as well as orbital observatories, the researchers proved that black holes of all sizes launch jets at the exact same critical point in their feeding cycle.[1][2]

The team tracked tidal disruption events, the astronomical term for a star being torn apart by the immense gravitational forces of a supermassive black hole. Out of 20 such events studied, 10 provided data detailed enough to model both the black hole's accretion rate and the precise timing of its radio emissions.[1]

“We really wanted to figure out this massive puzzle,” said Andrew Mummery, a researcher at the Institute for Advanced Study. “Why do some supermassive black holes blast out radio jets right after shredding a star, while others just sit there looking completely dormant, only to suddenly fire up their jets months or even years later?”[2][5]

The models revealed that the delayed jets consistently switch on when the black hole’s feeding rate drops to exactly 2 percent of its Eddington limit. The Eddington limit represents the physical boundary where the outward pressure of a black hole's radiation perfectly balances the inward pull of its gravity.[1][5]

That specific 2 percent threshold is not new to astrophysics. It is the exact same trigger point already known to launch compact radio jets in stellar-mass black holes within the Milky Way—objects that weigh only about 10 times the mass of the sun.[1][3]

Finding this identical threshold in supermassive giants confirms that black hole accretion physics scales universally. The same fundamental rules govern the behavior of a 10-solar-mass black hole and a supermassive behemoth millions of times heavier, bridging a mass gap of roughly seven orders of magnitude.[1][2][3]

The process of consuming a star is highly chaotic, which explains why the jets carry so much energy. “When a black hole tears apart a star, it does not swallow everything neatly,” said Adelle Goodwin of Curtin University’s International Centre of Radio Astronomy Research. “Some of the material is consumed, and some is launched back into space in powerful jets and outflows.”[3][5]

Goodwin noted that these ejections act as a cosmic pressure-release valve. “You can think of it as a black hole burp, except these burps can blast material across enormous distances and influence the galaxies around them,” she said.[3]

Beyond resolving a theoretical debate, the universal threshold offers a highly practical tool for observational astronomy. Because researchers can now calculate exactly when a feeding black hole's accretion rate will decay to the 2 percent mark, they can predict the precise arrival window of delayed jets.[1][5]

That predictability allows observatories to book scarce telescope time months in advance. As next-generation facilities like the Square Kilometer Array prepare to begin science operations in 2028, astronomers will no longer have to monitor dormant black holes continuously; they can simply schedule their observations for the exact period the 2 percent threshold is crossed.[1]