Indications of Intermediate-Scale Anisotropy of Cosmic Rays with Energy Greater Than 57 EeV in the Northern Sky Measured with the Surface Detector of the Telescope Array Experiment
Creators: name: The Telescope Array Collaboration
name: Abbasi, R. U.
name: Abe, M.
name: Abu-Zayyad, T.
name: Allen, M.
name: Anderson, R.
name: Azuma, R.
name: Barcikowski, E.
name: Belz, J. W.
name: Bergman, D. R.
name: Blake, S. A.
name: Cady, R.
name: Chae, M. J.
name: Cheon, B. G.
name: Chiba, J.
name: Chikawa, M.
name: Cho, W. R.
name: Fujii, T.
name: Fukushima, M.
name: Goto, T.
name: Hanlon, W.
name: Hayashi, Y.
name: Hayashida, N.
name: Hibino, K.
name: Honda, K.
name: Ikeda, D.
name: Inoue, N.
name: Ishii, T.
name: Ishimori, R.
name: Ito, H.
name: Ivanov, D.
name: Jui, C. C. H.
name: Kadota, K.
name: Kakimoto, F.
name: Kalashev, O.
name: Kasahara, K.
name: Kawai, H.
name: Kawakami, S.
name: Kawana, S.
name: Kawata, K.
name: Kido, E.
name: Kim, H. B.
name: Kim, J. H.
name: Kim, J. H.
name: Kitamura, S.
name: Kitamura, Y.
name: Kuzmin, V.
name: Kwon, Y. J.
name: Lan, J.
name: Lim, S. I.
name: Lundquist, J. P.
name: Machida, K.
name: Martens, K.
name: Matsuda, T.
name: Matsuyama, T.
name: Matthews, J. N.
name: Minamino, M.
name: Mukai, K.
name: Myers, I.
name: Nagasawa, K.
name: Nagataki, S.
name: Nakamura, T.
name: Nonaka, T.
name: Nozato, A.
name: Ogio, S.
name: Ogura, J.
name: Ohnishi, M.
name: Ohoka, H.
name: Oki, K.
name: Okuda, T.
name: Ono, M.
name: Oshima, A.
name: Ozawa, S.
name: Park, I. H.
name: Pshirkov, M. S.
name: Rodriguez, D. C.
name: Rubtsov, G.
name: Ryu, D.
name: Sagawa, H.
name: Sakurai, N.
name: Sampson, A. L.
name: Scott, L. M.
name: Shah, P. D.
name: Shibata, F.
name: Shibata, T.
name: Shimodaira, H.
name: Shin, B. K.
name: Smith, J. D.
name: Sokolsky, P.
name: Springer, R. W.
name: Stokes, B. T.
name: Stratton, S. R.
name: Stroman, T. A.
name: Suzawa, T.
name: Takamura, M.
name: Takeda, M.
name: Takeishi, R.
name: Taketa, A.
name: Takita, M.
name: Tameda, Y.
name: Tanaka, H.
name: Tanaka, K.
name: Tanaka, M.
name: Thomas, S. B.
name: Thomson, G. B.
name: Tinyakov, P.
name: Tkachev, I.
name: Tokuno, H.
name: Tomida, T.
name: Troitsky, S.
name: Tsunesada, Y.
name: Tsutsumi, K.
name: Uchihori, Y.
name: Udo, S.
name: Urban, F.
name: Vasiloff, G.
name: Wong, T.
name: Yamane, R.
name: Yamaoka, H.
name: Yamazaki, K.
name: Yang, J.
name: Yashiro, K.
name: Yoneda, Y.
name: Yoshida, S.
name: Yoshii, H.
name: Zollinger, R.
name: Zundel, Z.
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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 year 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$^\circ$-radius circles. The hotspot has a Li-Ma statistical significance of 5.1$σ$, and is centered at R.A.=146.7$^{\circ}$, Dec.=43.2$^{\circ}$. The position of the hotspot is about 19$^{\circ}$ off of the supergalactic plane. The probability of a cluster of events of 5.1$σ$ significance, appearing by chance in an isotropic cosmic-ray sky, is estimated to be 3.7$\times$10$^{-4}$ (3.4$σ$).
description: 16 pages, 3 figures, accepted for publication in the ApJ Letters