Experts of the Harvard-Smithsonian Center for Astrophysics (Massachusetts, USA) revealed that a black hole, which is located in a galaxy 665 million light years from the earth, swallowed a star in 2018 and is currently “burping” it, that is, expelling material belonging to that consumed celestial body.
The novelty was known following an investigation carried out by the aforementioned institution and which was published in the scientific journal The Astrophysical Journal. “This took us completely by surprise: naI had never seen anything like this before,” said researcher Yvette Cendes, lead author of this study.
In this sense, the team reported that it detected an unusual outburst while checking the tidal disruption events (TDE)), a phenomenon that occurs when invading stars are “spaghettised” by black holes. Precisely, the activity of an event called “AT2018hyz”.
The radio data of the Very Large Array (VLA), in New Mexico, showed that the black hole had mysteriously reanimated in June 2021. CEndes and the team rushed to examine the event more closely.
In this context, it was discovered that the black hole it is ejecting material that travels at half the speed of light. Nevertheless, they weren’t sure why the release was delayed for several years, since usually this astronomical object expels the waste of what it consumes instantly.
However, they believe that this phenomenon will help to better understand the feeding behavior of black holes, which Cendes compares to “belching” following a meal.
“We have been studying TDEs with radio telescopes for more than a decade, and sometimes we find that they glow in radio waves as they shed material as the black hole consumes the star for the first time,” said Edo Berger, professor of astronomy at Harvard and CfA, and co-author of the new study.
“But in AT2018hyz there was radio silence for the first three years and has now brightened dramatically to become one of the brightest radio TDEs ever observed“, he explained.
What are tidal disruption events
TDEs are the phenomena that occur when a star approaches a black hole. As the celestial body approaches that object, gravitational forces begin to stretch or spaguetear the star, generating a sparkle.
Possibly, elongated material spirals around the black hole and heats up, creating illumination that astronomers can detect from millions of light years away.
Occasionally, some spaghetti material is thrown back into space and astronomers compare it with black holes eating messilysince not everything they try to consume makes it to their mouths.
But the emission, known as the outflow, normally develops rapidly following a TDE occurs, not years later. “It’s as if AT2018hyz has abruptly started belching out a bunch of material from the star that it ate up years ago,” explains Cendes.
In this case, the “burps” are resounding, because the flow of material travels at a speed of 50% of the speed of light.
“This is the first time we have witnessed such a long delay between feeding and output. The next step is to explore whether this really happens more often and we just haven’t been looking at TDEs late enough in their evolution,” Berger said.