Scientists have identified the timing and conditions under which supermassive black holes release powerful jets of material, a phenomenon often described as black hole “burps.” These jets occur after black holes feed on stars, blasting streams of matter vast distances into space.
Black holes are regions of space where gravity is so intense that nothing, not even light, can escape beyond their event horizon, the point of no return. Contrary to their reputation as cosmic vacuums, black holes are actually inefficient and turbulent consumers, destroying stars well before matter crosses the event horizon.
Dr. Adelle Goodwin, an astrophysicist at Curtin University in Western Australia and a Forrest Research Foundation fellow, explained that only about half of the disrupted star’s material ultimately falls into the black hole. The remainder is expelled in high-energy jets and outflows, which can be so extensive that they influence the evolution of entire galaxies.
Until now, astrophysicists lacked clarity on the timing of these jets, which appeared inconsistently after stars were torn apart — sometimes months or years later. New research published in the journal *Nature Astronomy* by Goodwin and co-author Dr. Andrew Mummery of the Institute for Advanced Study sheds light on this puzzle. The pair analyzed data from 20 tidal disruption events, instances where stars are shredded by supermassive black holes, using radio telescopes to observe jet emissions.
Their findings reveal that supermassive black holes, which vary in mass from hundreds of thousands to billions of times that of the sun, emit jets at two distinct stages during their feeding process. The first phase occurs when the black hole is consuming material at very high rates. The second phase takes place hundreds to thousands of days later, once the feeding rate declines to approximately 2% of the black hole’s maximum accretion capability. This threshold matches the point at which smaller stellar-mass black holes, typically 10 to 50 times the mass of the sun, are known to produce similar jets.
According to Goodwin, the discovery that black holes of vastly different sizes launch jets at comparable stages in their feeding cycles allows for more accurate predictions of jet activity. This improved understanding will help researchers better schedule telescope observations, optimizing the use of valuable resources.
“This work enables us to not only determine when jets occur but also to explore their strength and how that correlates with black hole properties,” Goodwin said.
Dr. Sara Webb, an astrophysicist at Swinburne University not involved in the study, noted that the research contributes to unraveling basic mechanisms behind the behavior of the universe’s most extreme objects. She remarked that the results demonstrate “supermassive black holes behave rather predictably at two distant periods in their evolution,” connecting these behaviors to observations made of smaller black holes.
The study represents a significant advance in understanding black hole feeding dynamics and their broader impact on galactic environments.