Astronomers solve the mystery of black holes' delayed cosmic 'burps'

Supermassive black holes are notoriously messy when devouring a star, but they can also linger over their meals, letting out massive radio "burps" months or even years after their cosmic feast appears finished. Now, scientists tracking these events have found there is no one-size-fits-all model for how black holes digest stellar material. Speaking Monday (June 15) at the 248th meeting of the American Astronomical Society in California, Kate Alexander, an astronomer at the University of Arizona who has been studying these events, said the behavior depends instead on their shifting dietary phases. "Sometimes, after it seems like they are done eating, they may get indigestion and they may let out a large radio 'burp,'" Alexander said during a press conference on Monday. "These late-time radio burps can appear when the black hole eats too fast or eats too slowly, so you should always eat the right speed if you want to avoid indigestion." Her recent research focuses on Tidal Disruption Events, or TDEs , which are cosmic catastrophes that occur when an unlucky star wanders too close to a supermassive black hole. As the star nears the behemoth, intense gravitational fields shred it into a spaghetti-like stream of gas debris in a process known as " spaghettification ." Because these events are rare, occurring roughly once every 100,000 years in any given galaxy, astronomers must monitor a large number of galaxies just to spot them. …