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In astrophysics, gamma rays are conventionally defined as having photon energies above 100 keV and are the subject of gamma-ray astronomy, while radiation below 100 keV is classified as X-rays and is the subject of X-ray astronomy. Gamma rays are ionizing radiation and are thus hazardous to life.
Gamma rays, at the high-frequency end of the spectrum, have the highest photon energies and the shortest wavelengths—much smaller than an atomic nucleus. Gamma rays, X-rays, and extreme ultraviolet rays are called ionizing radiation because their high photon energy is able to ionize atoms, causing chemical reactions. Longer-wavelength ...
Gamma-ray astronomy is a subfield of astronomy where scientists observe and study celestial objects and phenomena in outer space which emit cosmic electromagnetic radiation in the form of gamma rays, [nb 1] i.e. photons with the highest energies (above 100 keV) at the very shortest wavelengths.
Swift, a gamma-ray telescope, which provides data products not previously available from prior missions, including spectra, images, and lightcurves. Fermi, an American gamma-ray telescope; AGILE, an Italian gamma-ray telescope; HAWC, a ground-based gamma-ray and cosmic ray observatory in Mexico; Calorimetric Electron Telescope, a Japanese ...
GRB 221009A could have produced multi-TeV gamma rays for more than a week after the prompt phase, with this feature being unique to GRB 221009A, [51] far longer compared to other bursts such as GRB 180720B, which produced multi-TeV gamma rays for ten hours after the prompt phase, and GRB 190829A, which produced multi-TeV gamma rays for nearly ...
No gamma-ray bursts from within our own galaxy, the Milky Way, have been observed, [161] and the question of whether one has ever occurred remains unresolved. In light of evolving understanding of gamma-ray bursts and their progenitors, the scientific literature records a growing number of local, past, and future GRB candidates.
The ratio of primary cosmic ray hadrons to gamma rays also gives a clue as to the origin of cosmic rays. Although gamma rays could be produced near the source of cosmic rays, they could also be produced by interaction with cosmic microwave background by way of the Greisen–Zatsepin–Kuzmin limit cutoff above 50 EeV. [4] Ultra-high-energy ...
GRB 970228 [2] was the first gamma-ray burst (GRB) for which an afterglow was observed. [3] It was detected on 28 February 1997 at 02:58 UTC.Since 1993, physicists had predicted GRBs to be followed by a lower-energy afterglow (in wavelengths such as radio waves, x-rays, and even visible light), but until this event, GRBs had only been observed in highly luminous bursts of high-energy gamma ...