Cygnus X-3 in the context of Very high energy

A gamma ray, also known as gamma radiation (symbol γ), is a penetrating form of electromagnetic radiation arising from high-energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. It consists of the shortest wavelength electromagnetic waves, typically shorter than those of X-rays. With frequencies above 30 exahertz (3×10 Hz) and wavelengths less than 10 picometers (1×10 m), gamma ray photons have the highest photon energy of any form of electromagnetic radiation. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation gamma rays based on their relatively strong penetration of matter; in 1900, he had already named two less penetrating types of decay radiation (discovered by Henri Becquerel) alpha rays and beta rays in ascending order of penetrating power.

Gamma rays from radioactive decay are in the energy range from a few kiloelectronvolts (keV) to approximately 8 megaelectronvolts (MeV), corresponding to the typical energy levels in nuclei with reasonably long lifetimes. The energy spectrum of gamma rays can be used to identify the decaying radionuclides using gamma spectroscopy. Very-high-energy gamma rays in the 100–1000 teraelectronvolt (TeV) range have been observed from astronomical sources such as the Cygnus X-3 microquasar.

A very-high-energy gamma ray (VHEGR) is gamma radiation with photon energies of 100 GeV (gigaelectronvolt) to 100 TeV (teraelectronvolt), i.e., 10 to 10 electronvolts. This is approximately equal to wavelengths between 10 and 10 meters, or frequencies of 2 × 10 to 2 × 10 Hz. Such energy levels have been detected from emissions from astronomical sources such as some binary star systems containing a compact object. For example, radiation emitted from Cygnus X-3 has been measured at ranges from GeV to exaelectronvolt-levels. Other astronomical sources include BL Lacertae, 3C 66A Markarian 421 and Markarian 501. Various other sources exist that are not associated with known bodies. For example, the H.E.S.S. catalog contained 64 sources in November 2011.

A gamma ray, also known as gamma radiation (symbol γ), is a penetrating form of electromagnetic radiation arising from high-energy interactions like the radioactive decay of atomic nuclei or astronomical events like solar flares. Lower energy gamma radiation overlaps the upper end of X-ray radiation; they are distinguished by their different origins. Gamma ray photons have photon energy at the lower end from 10keV to 10,000 keV; ultra-high-energy gamma rays have energies over 10 keV. Paul Villard, a French chemist and physicist, discovered gamma radiation in 1900 while studying radiation emitted by radium. In 1903, Ernest Rutherford named this radiation gamma rays based on their relatively strong penetration of matter; in 1900, he had already named two less penetrating types of decay radiation (discovered by Henri Becquerel) alpha rays and beta rays in ascending order of penetrating power.

Gamma rays from radioactive decay are in the energy range from ten kiloelectronvolts (keV) to 10 megaelectronvolts (MeV), corresponding to the typical energy levels in nuclei with reasonably long lifetimes. The energy spectrum of gamma rays can be used to identify the decaying radionuclides using gamma spectroscopy. Very-high-energy gamma rays in the 100–1000 teraelectronvolt (TeV) range have been observed from astronomical sources such as the Cygnus X-3 microquasar.