Cosmic gamma rays with energies as high as 450 TeV (1012 eV) have been observed by the ASgamma observatory in Tibet – which is run jointly by China and Japan. This shatters the previous record of 75 TeV, which was set by the High-Energy-Gamma-Ray Astronomy observatory on the Canary Islands.
ASgamma detected 24 gamma rays with energies in the 100-450 TeV range. The particles appear to originate in the Crab Nebula, which is a supernova remnant about 6000 light-years away. It is home to a pulsar – a rapidly rotating neutron star that broadcasts a bright beam of electromagnetic radiation.
Astronomers believe that gamma rays in the 100-450 TeV range are created when much higher energy electrons in the petaelectronvolt (1015 eV) range interact with the cosmic microwave background – radiation released just after the Big Bang that permeates the universe. These electrons are believed to be accelerated to such high energies by the swirling magnetic fields generated by the pulsar. Indeed, the ASgamma researchers describe the Crab Nebula pulsar as “the most powerful natural electron accelerator known so far in our galaxy”.
ASgamma looks for high-energy gamma rays by detecting the shower of secondary particles that rain ...