This Friday, scientists eager to learn more about the most violent processes in the universe will celebrate. The day marks the official inauguration of the southern site of the Pierre Auger Observatory, a project to study the highest-energy cosmic rays. So far, there is no consensus on what type of cosmic object (perhaps a black hole?) can create the highest-energy cosmic rays, which have energies 10 million times higher than the world's highest-energy particle accelerator. Physicists don’t even agree on the mechanism that can propel particles to such high energies. It might be some sort of shock wave, but nothing is known for sure.
One of the 1600 detector tanks of the Auger Observatory
Auger’s southern observatory is located in Malargüe, Argentina, just east of the Andes Mountains. It consists of an array of 1600 detectors spread over 3000 square kilometers in Argentina's Mendoza Province. Surrounding the array is a set of 24 fluorescence telescopes that view the faint ultraviolet light emitted by the cosmic-ray shower particles as they cascade through the Earth’s atmosphere. The project's second phase includes plans for a northern hemisphere site in Colorado, USA, and enhancements to the southern hemisphere site.
The Pierre Auger collaboration already published its first physics results in the fall of 2007, while its array of detectors was still under construction. The collaboration found that the arrival directions of the highest-energy cosmic rays are not evenly distributed across the sky. Instead, the arrival directions correlate with the distribution of nearby galaxies that contain actively radiating black holes. The result made the cover of the Nov. 9, 2007, issue of Science magazine, and the result was selected as one of the most important scientific breakthroughs in 2007 by several publications.
The Auger Web site features a nice program that allows anybody in the world to explore a one-percent sample of the cosmic rays recorded by the southern observatory so far. The site also features photos and videos.
