Ultra-high-energy cosmic ray

In astroparticle physics, an ultra-high-energy cosmic ray (UHECR) is a cosmic ray with an energy greater than 1 EeV (1018 electronvolts, approximately 0.16 joules),[1] far beyond both the rest mass and energies typical of other cosmic ray particles. The origin of these highest energy cosmic ray is not known.[2]

These particles are extremely rare; between 2004 and 2007, the initial runs of the Pierre Auger Observatory (PAO) detected 27 events with estimated arrival energies above 5.7×1019 eV, that is, about one such event every four weeks in the 3,000 km2 (1,200 sq mi) area surveyed by the observatory.[3]

  1. ^ Alves Batista, Rafael; Biteau, Jonathan; Bustamante, Mauricio; Dolag, Klaus; Engel, Ralph; Fang, Ke; Kampert, Karl-Heinz; Kostunin, Dmitriy; Mostafa, Miguel; Murase, Kohta; Oikonomou, Foteini; Olinto, Angela V.; Panasyuk, Mikhail I.; Sigl, Guenter; Taylor, Andrew M.; Unger, Michael (2019). "Open Questions in Cosmic-Ray Research at Ultrahigh Energies". Frontiers in Astronomy and Space Sciences. 6: 23. arXiv:1903.06714. Bibcode:2019FrASS...6...23B. doi:10.3389/fspas.2019.00023.
  2. ^ Cite error: The named reference Kotera-2011 was invoked but never defined (see the help page).
  3. ^ Watson, L. J.; Mortlock, D. J.; Jaffe, A. H. (2011). "A Bayesian analysis of the 27 highest energy cosmic rays detected by the Pierre Auger Observatory". Monthly Notices of the Royal Astronomical Society. 418 (1): 206–213. arXiv:1010.0911. Bibcode:2011MNRAS.418..206W. doi:10.1111/j.1365-2966.2011.19476.x. S2CID 119068104.