| Abstract from DBPedia | Gamma-ray astronomy is the astronomical observation of gamma rays, the most energetic form of electromagnetic radiation, with photon energies above 100 keV. Radiation below 100 keV is classified as X-rays and is the subject of X-ray astronomy. In most known cases, gamma rays from solar flares and Earth's atmosphere are generated in the MeV range, but it is now known that gamma rays in the GeV range can also be generated by solar flares. It had been believed that gamma rays in the GeV range do not originate in the Solar System. As GeV gamma rays are important in the study of extra-solar, and especially extra-galactic, astronomy, new observations may complicate some prior models and findings. The mechanisms emitting gamma rays are diverse, mostly identical with those emitting X-rays but at higher energies, including electron–positron annihilation, the inverse Compton effect, and in some cases also the decay of radioactive material (gamma decay) in space reflecting extreme events such as supernovae and hypernovae, and the behaviour of matter under extreme conditions, as in pulsars and blazars. 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.ガンマ線天文学（ガンマせんてんもんがく、英語：gamma-ray astronomy）は観測天文学の一分野で、宇宙から飛来するガンマ線を研究する。ガンマ線を放射する天体は超新星残骸、パルサー、活動銀河核等がある。 (Source: http://dbpedia.org/resource/Gamma-ray_astronomy) |
