Washington: A giant black hole ripped apart a star and then binged on its remains for about a decade, setting a record for the longest such episode, say scientists who made the discovery using data from NASA’s Chandra X-ray Observatory and other space telescopes.
A trio of orbiting X-ray telescopes, including Swift satellite as well as ESA’s XMM-Newton, found evidence for a “tidal disruption event” (TDE), wherein the tidal forces due to the intense gravity from a black hole can destroy an object – such as a star – that wanders too close.
During a TDE, some of the stellar debris is flung outward at high speeds, while the rest falls toward the black hole.
As it travels inwards to be ingested by the black hole, the material heats up to millions of degrees and generates a distinct X-ray flare.
“We have witnessed a star’s spectacular and prolonged demise,” said Dacheng Lin from the University of New Hampshire in the UK.
“Dozens of tidal disruption events have been detected since the 1990s, but none that remained bright for nearly as long as this one,” said Lin, who led the study.
The extraordinary long bright phase of this event spanning over ten years means that among observed TDEs this was either the most massive star ever to be completely torn apart during one of these events, or the first where a smaller star was completely torn apart.
The X-ray source containing this force-fed black hole, known by its abbreviated name of XJ1500+0154, is located in a small galaxy about 1.8 billion light years from Earth.
The source was detected in an XMM-Newton observation on July 23rd in 2005, and reached peak brightness in a Chandra observation on June 5 in 2008.
These observations show that the source became at least 100 times brighter in X-rays. Since then, Chandra, Swift, and XMM-Newton have observed it multiple times.
The sharp X-ray vision of Chandra data shows that XJ1500+0154 is located at the center of its host galaxy, the expected location for a supermassive black hole.
“For most of the time we’ve been looking at this object, it has been growing rapidly,” said James Guillochon of the Harvard-Smithsonian Centre for Astrophysics in the US.
“This tells us something unusual like a star twice as heavy as our Sun is being fed into the black hole,” said Guillochon.
The conclusion that supermassive black holes can grow so rapidly may help explain how supermassive black holes were able to reach masses about a billion times higher than the Sun when the universe was only about a billion years old.
“This event shows that black holes really can grow at extraordinarily high rates. This may help understand how precocious black holes came to be,” said Stefanie Komossa of QianNan Normal University for Nationalities in China.
The findings were published in the journal Nature Astronomy.