At https://archaeologynewsnetwork.blogspot.com/2019/08/mechanism-for-gamma-… … short and intense flashes of energetic radiation, known as gamma ray bursts, were discovered back in the late 1960s by the Vela satellites sent to monitor man made nuclear explosions from space. Since then they have become a focus of great interest to astronomers. In the late 1990s it was discovered they had an association with what is thought to represent the death and collapse of stars. In the 2000s short bursts were confirmed, we are told, during observation of gravitational waves by the LIGO and Virgo detectors) etc. In spite of the mainstream theory of their origins the picture is far from clear, we are also told, as scientists do not know how the high energy gradient is produced. Perhaps the post on the bow shock phenomenon may help. However, last January NASA detected a bright burst in a distant galaxy – and extremely high energy photons. In a paper in Astrophysical Journal Letters scientists from Novgorod and Jerusalem universities combined data to show radiation must have originated in a jet moving at almost the speed of light, emitted by electrons accelerated to TeV energies within the jet in a process known as the 'inverse compton mechanism' in which ultra high energy electrons collide with low energy photons and boost their energy.
At https://phys.org/news/2019-07-x-rays-black-holes-cosmic-sea.html .. like whirlpools in the oceans spiralling black holes in space create a swirling torrent around them. However, rather than eddies of wind or water black holes generate disks of gas and dust heated to hundreds of millions of degrees – and it glows in X-ray light.
At https://phys.org/news/2019-07-highest-energy-gamma-rays-tibet-asgamma.html … a Chinese and Japanese collaboration = the Tibet AS gamma experiment. It has observed the most energetic gamma ray burst yet recorded – coming from the Crab Nebula.