This orange dot is a gamma-ray burst which appears to be a sign of an unusual event
IT/A. Levan, A. Martin-Carrillo et al.
A black hole that was eaten by a star appears to have gotten revenge by consuming the star from the inside, producing a gamma-ray burst spotted about 9 billion light-years from Earth.
The burst, called GRB 250702B, was first spotted by NASA’s Fermi Gamma-ray Space Telescope in July. Such bursts are bright flashes caused by jets fired by energetic events, such as the collapse of massive stars into black holes or the merger of neutron stars, and they usually last no more than a few minutes.
GRB 250702B, however, lasted 25,000 seconds – or about 7 hours – making it the longest known gamma-ray burst. Scientists had struggled to explain it, but Eliza Neights of NASA’s Goddard Space Flight Center in the United States and her colleagues now suggest an unusual and rare possibility.
“The only [model] what naturally explains the properties observed in GRB 250702B is the fall of a stellar mass black hole into a star,” the researchers write in an article on their work.
In more typical long gamma-ray bursts, a massive star collapses to form a black hole, firing off jets as it dies. In this case, the team suggests the opposite: a pre-existing black hole spiraled into a companion star whose outer layers expanded late in its life, causing the black hole to lose angular momentum and fall toward the star’s core.
The black hole would then have consumed the star from the inside out, producing the powerful jets seen as GRB 250702B and possibly triggering a faint supernova, although too faint to be detected at this distance, even with the James Webb Space Telescope.
This explanation makes sense for how an ultra-long burst like this could occur, says Hendrik van Eerten of the University of Bath in the United Kingdom. “The argument made in this article is very convincing,” he says.
Neights and his colleagues hope that more events like this can be observed in the future, thanks to upcoming telescopes like the Vera Rubin Observatory in Chile. For the moment, this gamma-ray burst remains “an absurdity”, believes Van Eerten.
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