Space telescope detects supernova blast so bright instruments couldn’t keep up
A space telescope has detected a gamma ray burst (GRBs) so bright instruments couldn’t keep up with it, triggered by the collapse of a massive, distant star.
Gamma ray bursts are hugely energetic explosions – and this is believed to be the brightest ever observed.
It was accompanied by a huge supernova explosion, leaving behind a black hole.
Dr Peter Veres, an assistant professor with CSPAR, said: "During a GRB, we see the death of a massive star, approximately 30 times more massive than the sun, and the formation of a black hole."
"The black hole launches a very fast jet close to the speed of light, and the jet will produce the gamma-ray burst. At later times, GRBs are visible at other wavelengths as well, from radio, or optical through very high-energy gamma-rays, which is called the afterglow of the GRB.
"This GRB was so bright, the afterglow showed up in the gamma ray burst monitor, which is very uncommon, and we could follow it for almost three hours.”
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The explosion came from 2.4 billion light-years away in the constellation Sagitta.
GRB 221009A is also one of the nearest and possibly most energetic GRBs ever found, as detailed in a paper on the arXiv preprint server, which has been accepted for publication in The Astrophysical Journal Letters.
The GBM is an instrument in low-Earth orbit aboard the Fermi Gamma-ray Space Telescope that can see the entire gamma-ray sky not blocked by the Earth and hunts for GRBs as part of its main programme.
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"This gamma-ray burst was extremely bright. We expect to see one like this only every 10,000 years or so," says Dr Veres.
"We routinely detect GRBs at a rate of about five per week and keep an eye out if any of the GRBs are special in some way.
“This one was so bright, the instrument couldn't keep up with the large number of incoming photons. Most of the work, led by Stephen Lesage, was to figure out how to reconstruct the lost counts."
When the gamma rays enter these detectors, they interact with crystals in the instrument. The more energetic the gamma ray, the more light is produced.
By seeing which crystals light up, the GBM can tell the direction of the bursts. In all, the Fermi instrument has discovered over 3,500 GRBs, and 221009A is by far the brightest ever detected.
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