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Correlation of the highest-energy cosmic rays with nearby extragalactic objects
Science (New York, N.Y.)
|November 10, 2007
Summary
High-energy cosmic rays detected at the Pierre Auger Observatory correlate with nearby active galactic nuclei (AGN). This suggests these energetic particles originate from extragalactic sources within 75 megaparsecs.
Area of Science:
- Astrophysics
- Particle Physics
- Cosmic Ray Physics
Background:
- The origin of ultra-high-energy cosmic rays (UHECRs) remains a significant mystery in astrophysics.
- Understanding UHECR sources is crucial for comprehending particle acceleration mechanisms in the universe.
Purpose of the Study:
- To investigate the potential correlation between the arrival directions of UHECRs and known astrophysical objects.
- To test the hypothesis of an isotropic distribution versus an anisotropic, source-driven distribution of UHECRs.
Main Methods:
- Analysis of cosmic ray data collected over 3.7 years at the Pierre Auger Observatory.
- Statistical comparison of UHECR arrival directions with the positions of active galactic nuclei (AGN) within a specific distance.
Main Results:
- A statistically significant correlation was found between UHECRs (energy > 6 x 10^19 eV) and the locations of nearby AGN (within ~75 Mpc).
- The hypothesis of an isotropic cosmic ray distribution was rejected with >99% confidence.
- The observed correlation supports the theory that these high-energy particles originate from nearby extragalactic sources.
Conclusions:
- Active Galactic Nuclei (AGN) or similar spatially distributed objects are likely sources of the highest-energy cosmic rays.
- The findings suggest minimal flux reduction from cosmic background radiation interactions, implying proximity of the sources.
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