Ravenous black holes often rip apart and feed off collapsing stars, but for how long?
Apparently, a black hole's mealtime can go on for about a decade, a record-breaking duration 10 times longer than any previous episode of a star's death, a new study revealed.
Feeding Frenzy
Using data from three different X-ray telescopes, scientists from the University of Hampshire detected a giant black hole that destroyed a nearby star about 1.8 billion light years away from Earth. The black hole went on to feed off the dead star's remains for 10 years.
"We have witnessed a star's spectacular and prolonged demise," said study lead author Dacheng Lin. He and his colleagues analyzed data from NASA's Swift Satellite and Chandra X-ray observatory, as well as the X-MM Newton from the European Space Agency.
Known as a tidal disruption event, the dying star got close to the event horizon of a supermassive black hole and got pulled apart by the black hole's tidal forces.
Dozens of these tidal disruption events have been discovered since the 1990s. However, Lin said none has remained bright for nearly as long as a decade.
Extraordinary Brightness
During a tidal disruption event, some stellar debris is tossed outward at high speeds, while the rest moves toward the black hole. As the stellar debris gets ingested by the black hole, it heats up to millions of degrees and produces multiwavelength flares, which can be seen by satellites.
Previous X-ray flares are short-lived and become faint in a year, but the super-long X-ray flare detected by Lin and his team, which is called XJ1500+0154, has been bright for close to a decade.
This extraordinary phase may mean that either this was the most massive star ever to be ripped apart, or a smaller star was first completely torn apart.
Furthermore, data suggests that radiation surrounding the black hole has surpassed Eddington limit — the balance between outward pressure from hot gas and the inward pull of the black hole.
Scientists say such rapid expansion may help pinpoint how supermassive black holes can reach masses a billion times higher than that of the sun when the universe was only a billion years old.
Meanwhile, based on the team's model, the feeding supply of the giant black hole would be significantly lessened in the next 10 years. It will then begin to fade in the next several years.
The findings of the study are published in Nature Astronomy.
