Scientists have discovered the most powerful radiation and the longest afterglow from gamma burst (GRB). Observations change established ideas about the generation of gamma rays. This is reported in the Science magazine.
The 190829A event was recorded on August 29, 2019 with the help of Fermi and SWIFT Space Observatory in Eridan’s constellation. The source is located at a distance of about one billion light years, although typical GRBs are at a distance of about 20 billion light years (the size of the universe due to accelerated expansion is much higher than its age).
Astronomers conducted observations of the source through the complex of telescopes H.E.S.S. In Namibia. This tool registers the rains of particles that occur when high-energy photons are condensed to the Earth’s atmosphere. A relatively short distance to this gamma burst made it possible to measure the spectrum of the afterglow, which is the distribution of energies of radiation photons in the range of very high energies. The maximum energy reached 3.3 teraelectronvolt, which is about trillion times higher than that of the photons of the visible energy.
observations also showed the similarity between X-ray and gamma radiation. Theories assume that both components of radiation are created by individual mechanisms: the X-ray component comes from ultrafast electrons accelerated by strong magnetic fields during the flash, but it is considered that even the most powerful explosions are not able to speed up electrons to reproduce the gamma rays. Therefore, gamma radiation occurs in the collision of accelerated electrons with photons, increasing the energy of the latter.
But the surveillance of the afterglow of the GRB 190829A now show that both components, X-ray and gamma radiation disappeared synchronously. This suggests that X-ray and gamma radiation arose as a result of one mechanism, which still remains not known.
There are several varieties of gamma bursts, which are the brightest electromagnetic events in the universe. It is believed that the first arises when the neutron stars are configured in the double systems, which generates giant explosions, and the second-type bursts are associated with the collapse of the core of massive stars when the supernovae flashes. Short bursts with rigid gamma radiation, resembling gamma bursts of the first type, refer to sources of soft repetitive gamma bursts, many of which are in the Milky Way or in close galaxies.