Wow.

[johncarlosbaez@mathstodon.xyz]

Wow. A black hole may have fallen into a star, eating it up and causing three big gamma ray bursts! Never seen before.

The first gamma ray burst was detected by the Fermi Gamma-ray Space Telescope on July 2, 2025. The second came 47 minutes later. The third came 188 minutes after that. These bursts were also seen by X-ray detectors.

At first people thought these bursts were coming from within our galaxy. But a day later, the Very Large Telescope found they were from a distant galaxy. This was soon confirmed by the Hubble Space Telescope. So they had to be very powerful.

Repeated powerful bursts like this over a long period of time are unprecedented. Now a careful analysis has come out, which argues that they came from a black hole falling into a 'helium star'. This is a star that's already blown off its outer hydrogen layers, leaving a core of helium.

I'm not quite sure why they think it was a helium star - the paper is not easy to follow for nonexperts like me - but I think it's because these stars are massive yet small in size. They also considered the scenario of a black hole falling into a white dwarf, but rejected it.

These graphs show gamma rays as a function of time, detected by various detectors.

(1/2)