“The energy of the gamma rays was detected for several days”, the experts explain. Prior to this, gamma-ray bursts are typically detected around 20 billion light-years away (this time just 1 billion light-years away). and its glow could only be observed for a few hours each and at much lower energies.
“We were really sitting in the front row when this gamma-ray burst happened,” celebrates DESY co-author Andrew Taylor. The team caught the post-explosion glow immediately when it became visible to the HESS telescopes. “We were able to observe the afterglow for several days at unprecedented gamma ray energies,” Taylor says.
Its relatively short distance allowed detailed measurements of the glow spectrum, the distribution of ‘colors’ or energies of the radiation photons, in the very high energy range.
“We could determine the spectrum of GRB 190829A up to an energy of 3.3 tera-electron volts, which is about a trillion times more energetic than photons in visible light, “explains Edna Ruiz-Velasco of the Max Planck Institute for Nuclear Physics in Heidelberg.
“Our observations revealed curious similarities between X-rays and the very high-energy gamma ray emission from the blast glow,” the authors comment.
The theory states that the two emission components must be produced by separate mechanisms. But observations of the afterglow of GRB 190829A show that both components, X-rays and gamma rays, faded in sync. This poses a challenge to the synchrotron origin of very high energy gamma ray emission.