Scientists unlock the timing of black hole 'burps' across all sizes

Black holes have a reputation for being cosmic vacuums, pulling everything into an inescapable void. The reality is messier. When a star wanders too close to a supermassive black hole, the encounter does not end in silent consumption. Instead, the black hole becomes what astrophysicist Adelle Goodwin describes as a very untidy eater, launching powerful jets of material back into space with enough force to reshape entire galaxies. For decades, astronomers have observed these jets—sometimes called black hole burps—but the timing remained baffling. A jet might arrive a year after the star's destruction, or three years, or five. The pattern seemed random. Now, researchers believe they have cracked the code.

When a star ventures within a black hole's gravitational reach, it does not cross the event horizon intact. The boundary of no return—the point where escape would require traveling faster than light—lies deep within the black hole's grip. But the star is destroyed long before reaching that threshold, torn apart by the differential gravity between its near and far sides, a process physicists call spaghettification. Only about half the stellar material actually falls into the black hole. The rest gets ejected violently outward, sometimes with consequences that ripple across an entire galaxy's evolution.

Goodwin, an astrophysicist at Curtin University in Western Australia and a Forrest Research Foundation fellow, led a study published in Nature Astronomy that examined 20 tidal disruption events—instances where supermassive black holes consumed stars. Working with co-author Andrew Mummery from the Institute for Advanced Study, the team used radio telescopes to track the jets as they moved outward through space. Radio frequencies proved essential; they are the only wavelength at which astronomers can actually watch these outflows in motion.

The breakthrough came from recognizing a pattern across all the black holes studied, regardless of their size. Supermassive black holes, which range from hundreds of thousands to billions of times the sun's mass, released jets in two distinct phases. The first burst occurred when the black hole was feeding at maximum intensity, consuming material at its highest possible rate. The second phase arrived much later—hundreds to thousands of days after the star's initial destruction—when the feeding rate had dropped to roughly 2 percent of that maximum capacity. That same 2 percent threshold, it turned out, was already known to trigger jets from stellar-mass black holes, much smaller objects weighing only 10 to 50 times the sun's mass.

The finding suggests a universal mechanism governing jet release across black holes of vastly different scales. A black hole does not care whether it weighs a million suns or a billion; it appears to follow the same rules about when to launch its jets. This consistency opens a practical door for astronomers. If the timing of jets depends on reaching specific feeding rates, scientists can now predict when those jets will appear, narrowing the observation windows needed to catch them and freeing up precious telescope time for other observations. Goodwin noted that the research also promises to illuminate not just when jets are released, but how powerful they become and whether that strength depends on the black hole's own properties.

Sara Webb, an astrophysicist at Swinburne University who was not involved in the research, called the work significant for understanding the most extreme objects in the universe. She highlighted how the study demonstrated that supermassive black holes behave predictably at two distinct periods in their feeding cycle, and how the researchers had successfully connected this behavior back to patterns already observed in much smaller stellar-mass black holes. The connection between objects separated by orders of magnitude in size suggests that black hole physics operates according to principles that transcend scale—a finding that could reshape how astronomers approach the study of these cosmic engines.