Searches for the sources of cosmic rays with energies (1–4)×1017 eV using the Yakutsk EAS array

We analyze the arrival directions of cosmic rays with energies E ₀≈(1–4)×10¹⁷ eV and zenith angles θ≤53≤ detected with the Yakutsk extensive air shower (EAS) array during 1974–2001. We show that ～10% of them form many clusters correlated with the Supergalactic plane. Enhanced particle fluxes arrive from the Supergalactic plane and the regions that are symmetrically adjacent to it at angles ±b _SG ≈ 6°.5. The relatively high concentrations of clusters of galaxies and quasars that bear a relationship to the large-scale structure of the Universe are observed in these regions.