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Active Galactic Nuclei as Ultra-High Energy Cosmic Ray Accelerators

AJAS · 2026 Physics and Astronomy (inferred)

Liam Whelan · Arizona Nevada Academy of Science

Overview

Ultra-high-energy cosmic rays (UHECRs) are the most energetic particles in the universe and have been studied extensively for over 20 years; however, due to various limitations, their sources remain unknown. While many sources have been proposed, active galactic nuclei (AGNs) are the most likely UHECR accelerators due to their high-energy environments and relativistic jets. This study examined the extent to which UHECR arrival directions and AGN positions correlate, using statistical and machine-learning methods. A cross-correlation analysis compared UHECR events observed by the Pierre Auger Observatory with AGNs in the Swift BAT 157-Month Hard X-ray Survey. Monte Carlo simulations determined the statistical significance of observed correlations. Additionally, a neural network model was constructed to predict AGN positions using a subset of UHECR event parameters. The results indicated that UHECRs above 5.7 × 10¹⁹ eV exhibit a stronger correlation with AGNs—79.17% of events are within 10° of an AGN—however, the results are only marginally statistically significant (p = 0.0831), showing that while AGNs are promising sources of UHECRs, other astrophysical processes must be considered. The correlation is further shown to increase with increasing UHECR energy. To some extent, the neural network model could predict AGN positions, further indicating a correlation, but it could be improved. Further research should include magnetic-field modeling, multiple messengers, and additional model parameters to better quantify the extent to which AGNs accelerate UHECRs.

Competition history

  • AJAS 2026 Category not listed

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Source: AAAS Annual Meeting (Confex) / American Junior Academy of Science

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