Astronomers have used the Very Large Telescope (VLT) to observe a distant black hole feeding on a star, revealing that black holes do not consume everything they pull in. Instead, the observations showed that a large amount of material is thrown back into space during the process, reported Space.com.
The research focused on the black hole system Swift J1727.8-1613, located about 8,800 light-years from Earth. The system first drew attention in 2023 after a powerful outburst made it one of the brightest X-ray sources visible from Earth.
Researchers found that as the black hole stripped material from a nearby companion star, some of it was consumed while the rest was blasted back into space as high-speed jets and powerful black hole winds.
They also discovered that the largest outflows of material occurred when the black hole's feeding activity was much lower than scientists had previously believed.
Team leader Noel Castro Segura of the University of Warwick said people often imagine black holes simply swallowing everything around them.
However, he explained that the observations showed a much more complex process in which matter falls in, the system processes it and a surprising amount is expelled again.
Swift J1727.8-1613 consists of a black hole surrounded by an accretion disk made of material pulled from a companion star. The black hole's strong gravity heats this spinning disk, causing it to glow brightly.
Using the VLT, the team tracked the system over time as the black hole fed on the star.
Their observations created what researchers described as a "movie" of the feeding process, showing changes in the glowing disk while the black hole launched powerful jets into space.
The study also found that even after the black hole's feeding frenzy had slowed down, it continued producing dense gas winds.
Researchers suggested that the total amount of material thrown away could eventually equal the amount consumed by the black hole, meaning nearly half of its stellar meal may be lost to space.
Segura said that if black holes continue shedding material even after their biggest outbursts, they may be much less efficient eaters than previously thought.
He added that a significant fraction of the material may never reach the black hole at all, changing scientists understanding of how binary star systems in galaxies evolve.
Kyle Solomons, a doctoral researcher at the University of Cape Town, said scientists usually focus on the dramatic beginning of a black hole outburst, but the observations showed that the final stages can be just as intense.
The findings were published in the Monthly Notices of the Royal Astronomical Society (MNRAS).
