Air shower simulation; credit:
Cosmus team
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Ultra-high--energy
Cosmic Ray Astronomy and
Astrophysics with the Pierre Auger Observatory
Ultra-high--enegry cosmic rays are the
most energetic particles in the Universe. These particles cannot
reach the surface of the Earth: they interact with the Earth's
atmosphere, and produce secondary particle air-showers.
The Pierre Auger Observatory
detects the signatures of these air showers, through telescopes
looking for the fluorescence emission from the atmosphere in
response to the shower, and through a vast surface array of tanks
filled with water, looking for the for the Cerenkov emission of the
secondary particles when they reach the ground and propagate in the
tank water. From these signatures, the arrival direction and energy
of each particle can be reconstructed.
Pierre Auger observations of ultra-high--energy cosmic rays
will help answer long-standing questions on the energy spectrum, the
composition, and, ultimately, the sources of these highest-energy
particles. Recently, The Pierre Auger collaboration announced that
the highes-energy cosmic-ray sky appears to be anisotropic, with a
statistical significance of the measured deviation from isotropy
better than 1% in an a priori defined statistical test (access the
Science letter here
and a longer, more deltailed description of the statistical analysis
here).
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Members of the Chicago Auger group have been actively working on
better understanding this anisotropy signal, and evaluate its
potential to point us directly to the sources of ultra-high--energy
cosmic rays. Our contributions towards this direction can be
accessed here (Auger password required for full text).
Recent refereed Pierre Auger collaboration publications can be found
here.
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