On 1 August 2024, the Chinese-European Einstein Probe satellite detected an X-ray flash lasting about two minutes, originating in the constellation Pegasus. At the same time, the Fermi Gamma-ray Space Telescope recorded a gamma-ray burst from the same region of the sky. Optical analysis showed that the bursts occurred at a redshift of 1.67, meaning they were emitted roughly ten billion years ago.
It was mainly the “afterglow” of the explosion that provided astronomers with crucial information about the origin of the flash. The signal remained visible in the optical and infrared bands for months. The event was identified as a type 1c supernova—a catastrophic explosion marking the end of a star’s life.
Although a supernova origin had previously been suspected, scientists were unable to confirm it until now. Thanks to the extreme sensitivity of the James Webb Space Telescope, launched in 2021, confirmation has finally been achieved. The spectrum measured by Webb matches those of nearby supernovae, while the light curve observed with the Hubble Space Telescope also supports the supernova interpretation. 'It is extremely interesting that, thanks to fast X-ray and gamma-ray bursts, we can find and study supernovae at higher redshifts,' says Agnes van Hoof, PhD student at Radboud University and lead author of the study. 'We would not have found this supernova without the X-ray and gamma-ray burst.'
