Implications of a possible clustering of highest-energy cosmic rays.

Recently, a possible clustering of a subset of observed ultra-high energy cosmic rays above approximately 40 EeV (4 x 10(19) eV) in pairs near the supergalactic plane was reported. We show that a confirmation of this effect would provide information on the origin and nature of these events and, in case of charged primaries, imply interesting constraints on the extragalactic magnetic field. Possible implications for the most common models of ultra-high energy cosmic ray production in the literature are discussed.