Pierre Auger Observatory discovers extragalactic origin of highest-energy cosmic rays

In November 2007, the Auger project published results showing that the direction of origin of the 27 highest energy events were strongly correlated with the location of active galactic nuclei (AGN). An active galactic nucleus is a compact region at the centre of a galaxy that has a much higher than normal luminosity over at least some portion, and possibly all, of the electromagnetic spectrum. These results supported the theory that at the centre of each AGN is a large black hole exerting a magnetic field strong enough to accelerate a bare proton to energies of 1020 eV and higher.

The Auger observatory is the world’s largest and most accurate observatory for studying cosmic rays. It consists of 1600 surface detectors and 27 fluorescent telescopes and covers an area of 3000 km2. The Pierre Auger collaboration has made many low-energy incidents, which do not require physical analysis, available on the Public Event Display website.