American Astronomical Society, Astrophysical Journal Letters, 2(790), p. L21, 2014
DOI: 10.1088/2041-8205/790/2/l21
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We have searched for intermediate-scale anisotropy in the arrival directions of ultrahigh-energy cosmic rays with energies above 57 EeV in the northern sky using data collected over a 5 yr period by the surface detector of the Telescope Array experiment. We report on a cluster of events that we call the hotspot, found by oversampling using 20° radius circles. The hotspot has a Li-Ma statistical significance of 5.1σ, and is centered at R.A. = 146.°7, decl. = 43.°2. The position of the hotspot is about 19° off of the supergalactic plane. The probability of a cluster of events of 5.1σ significance, appearing by chance in an isotropic cosmic-ray sky, is estimated to be 3.7 × 10-4 (3.4σ). © 2014. The American Astronomical Society. All rights reserved. ; 0 ; SCOPUS: ar.j ; info:eu-repo/semantics/published