A correlation between the highest energy cosmic rays and nearby active
  galactic nuclei detected by Fermi
  We analyze the correlation of the positions of gamma-ray sources in the Fermi
Large Area Telescope First Source Catalog (1FGL) and the First LAT Active
Galactic Nuclei (AGN) Catalog (1LAC) with the arrival directions of
ultra-high-energy cosmic rays (UHECRs) observed with the Pierre Auger
Observatory, in order to investigate the origin of UHECRs. We find that
Galactic sources and blazars identified in the 1FGL are not significantly
correlated with UHECRs, while the 1LAC sources display a mild correlation (2.6
sigma level) on a ~2.4 degree angular scale. When selecting only the 1LAC AGNs
closer than 200 Mpc, we find a strong association (5.4 sigma) between their
positions and the directions of UHECRs on a ~17 degree angular scale; the
probability of the observed configuration being due to an isotropic flux of
cosmic rays is 5x10^{-8}. There is also a 5 sigma correlation with nearby 1LAC
sources on a 6.5 degree scale. We identify 7 "gamma-ray loud" AGNs which are
associated with UHECRs within ~17 degree and are likely candidates for the
production sites of UHECRs: Centaurus A, NGC 4945, ESO 323-G77, 4C+04.77, NGC
1218, RX J0008.0+1450 and NGC 253. We interpret these results as providing
additional support to the hypothesis of the origin of UHECRs in nearby
extragalactic objects. As the angular scales of the correlations are large, we
discuss the possibility that intervening magnetic fields might be considerably
deflecting the trajectories of the particles on their way to Earth.
