A team led by Dr. Adelle Goodwin, an astrophysicist at Curtin University's International Centre of Radio Astronomy Research (ICRAR) and a Forrest Research Foundation Fellow, and Dr. Andrew Mummery of the Institute for Advanced Study in Princeton, has uncovered a surprisingly simple pattern behind black hole eruptions.
The breakthrough came after years of observing tidal disruption events, in which supermassive black holes shred stars that wander too close. By combining telescope data from Australia, the United States, India, South Africa and space-based observatories, the researchers built a clearer picture of how black holes behave as they consume matter.
The crucial insight did not arrive at a telescope, but during a conversation in a bar in Madrid, where Goodwin and Mummery were attending a scientific conference. They recognised that the same rule that governs jet formation in relatively small black holes also seemed to apply to their supermassive counterparts.
A key mystery the team wanted to explain was why black holes do not always launch jets at the same time after a star is torn apart. Sometimes a jet appears almost immediately; in other cases the black hole stays quiet for months or even years before suddenly producing a detectable radio outflow.
"We were looking at these events and asking why the timing was so different," Dr. Goodwin said. "Then the pattern became clear. The delayed jets were appearing when the black hole's feeding rate dropped to the same critical point already known from much smaller black holes. That was the moment we realised this was not just a quirk of one type of black hole, but it looked like a rule that applied across the Universe."
As material spirals toward a black hole, not all of it disappears beyond the event horizon. Some matter is expelled into space through powerful jets and outflows. "When a black hole tears apart a star, it does not swallow everything neatly," Dr. Goodwin said. "Some of the material is consumed, and some is launched back into space in powerful jets and outflows. 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."
The finding suggests that the mechanism behind these outflows may be universal, operating at the same critical feeding rate whether the black hole is a stellar-mass object or a supermassive giant. The result could help astronomers predict when jets will appear and understand how black holes shape their host galaxies over cosmic time.