Ultra-high-energy gamma ray

[1] In a 18 May 2021 press release, China's Large High Altitude Air Shower Observatory (LHAASO) reported the detection of a dozen ultra-high-energy gamma rays with energies exceeding 1 peta-electron-volt (quadrillion electron-volts or PeV), including one at 1.4 PeV, the highest energy photon ever observed.

The authors of the report have named the sources of these PeV gamma rays PeVatrons.

In 2024, LHAASO announced the detection of a 2.5 PeV gamma ray originating from the Cygnus X region.

Discounting the relatively weak effect of gravity, they travel in a straight line from their source to an observer.

[4] Ultra-high-energy gamma rays interact with magnetic fields to produce positron-electron pairs.