Correlation of the highest energy cosmic rays with nearby extragalactic objects

TL;DR

This study analyzes data from the Pierre Auger Observatory and finds a significant correlation between ultra-high-energy cosmic rays and nearby active galactic nuclei, supporting the idea that these cosmic rays originate from extragalactic sources within 75 megaparsecs.

Contribution

It provides the first strong statistical evidence linking the highest energy cosmic rays to nearby extragalactic objects, specifically AGN, using a large dataset and a priori testing.

Findings

Significant correlation between cosmic rays and AGN within 75 Mpc

Rejection of isotropic distribution hypothesis at 99% confidence

Supports extragalactic origin hypothesis for ultra-high-energy cosmic rays

Abstract

Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above ~ 6x10^{19} electron volts and the positions of active galactic nuclei (AGN) lying within ~ 75 megaparsecs. We rejected the hypothesis of an isotropic distribution of these cosmic rays with at least a 99% confidence level from a prescribed a priori test. The correlation we observed is compatible with the hypothesis that the highest energy particles originate from nearby extragalactic sources whose flux has not been substantially reduced by interaction with the cosmic background radiation. AGN or objects having a similar spatial distribution are possible sources.