A group of telescopes has recorded for the first time diffuse ultra-high-energy gamma rays that travel along with the Milky Way galaxy. Details are published by Physical Review Letters.
A huge complex of telescopes in Tibet recorded the first evidence of the propagation of ultra-high-energy gamma rays through the Milky Way at a power of almost one peta-electron volt. This is three orders of magnitude more than any known cosmic ray-induced gamma radiation. The particles that humans have accelerated in modern laboratories on Earth have not even come close to such powers.
The data obtained is the first evidence of the existence of as yet undetected stellar accelerators, which emit cosmic rays for millions of years.
Cosmic rays are high-energy particles, mostly protons, that travel through space. Millions of these particles pass through our bodies every day but are considered harmless.
Since 1990, dozens of researchers from China and Japan have searched for elusive, high-energy cosmic gamma rays. The Tibet ASγ Experiment Collaboration made the discovery using nearly 70,000 square meters of ground-based arrays and underground muon detectors on the Tibetan Plateau, over 4,000 meters above sea level.
Scientists believe that high-energy gamma rays come from nuclear interactions between high-energy cosmic rays from the most powerful galactic sources and interstellar gas in the Milky Way galaxy. Detecting diffuse gamma rays above 100 teraelectronvolts is the key to understanding the origins of very high energy cosmic rays, which has been a mystery since their discovery in 1912.