Scientists have uncovered the timing behind the powerful "burps" of material launched by black holes after they consume stars. These burps, in the form of massive jets of material, can have a significant impact on the evolution of entire galaxies. A black hole is an extremely dense object with gravity so strong that nothing, not even light, can escape beyond a boundary called the event horizon. Dr. Adelle Goodwin, an astrophysicist from Curtin University in Western Australia, explains that black holes are "very messy eaters." When a star gets too close, it is torn apart before the event horizon. Only about half of the star's material is swallowed by the black hole, while the rest is expelled in powerful jets and outflows. However, the timing of these burps had previously been unclear, with some occurring a year after the star was destroyed, and others happening three or five years later. New research published in the journal Nature Astronomy by Dr. Goodwin and Dr. Andrew Mummery from the Institute for Advanced Study has shed light on this mystery. Using radio telescopes, they studied 20 tidal disruption events—cases where a star is torn apart by a black hole. Radio waves are the only frequency that allows scientists to observe the jets and outflows as they travel outward. The study found that supermassive black holes—those with masses ranging from hundreds of thousands to billions of times that of our sun—emit powerful jets in two distinct phases during their feeding cycle. The first phase occurs when the black hole is feeding at very high rates. The second phase happens hundreds to thousands of days after the star is destroyed, when the feeding rate drops to about 2% of the maximum rate. This same threshold is known to trigger burps in smaller stellar-mass black holes, which are about 10 to 50 times the mass of the sun. The research revealed that black holes of all sizes release jets at the same point in their feeding cycle. This finding could help scientists predict when such jets will occur, allowing them to optimize telescope observation times. Dr. Sara Webb, an astrophysicist at Swinburne University who was not involved in the study, noted that the research highlights the predictable behavior of supermassive black holes during two key phases of their evolution, linking this behavior to what has been observed in smaller stellar-mass black holes.