Evidence of Intermediate-scale Energy Spectrum Anisotropy of Cosmic Rays e ≥ 1019.2 eV with the Telescope Array Surface Detector

R. U. Abbasi; M. Abe; T. Abu-Zayyad; M. Allen; R. Azuma; E. Barcikowski; J. W. Belz; D. R. Bergman; S. A. Blake; R. Cady; B. G. Cheon; J. Chiba; M. Chikawa; A. Di Matteo; T. Fujii; K. Fujita; M. Fukushima; G. Furlich; T. Goto; W. Hanlon; M. Hayashi; Y. Hayashi; N. Hayashida; K. Hibino; K. Honda; D. Ikeda; N. Inoue; T. Ishii; R. Ishimori; H. Ito; D. Ivanov; H. M. Jeong; S. Jeong; C. C.H. Jui; K. Kadota; F. Kakimoto; O. Kalashev; K. Kasahara; H. Kawai; S. Kawakami; S. Kawana; K. Kawata; E. Kido; H. B. Kim; J. H. Kim; J. H. Kim; S. Kishigami; S. Kitamura; Y. Kitamura; V. Kuzmin; M. Kuznetsov; Y. J. Kwon; K. H. Lee; B. Lubsandorzhiev; J. P. Lundquist; K. Machida; K. Martens; T. Matsuyama; J. N. Matthews; R. Mayta; M. Minamino; K. Mukai; I. Myers; K. Nagasawa; S. Nagataki; R. Nakamura; T. Nakamura; T. Nonaka; A. Nozato; H. Oda; S. Ogio; J. Ogura; M. Ohnishi; H. Ohoka; T. Okuda; Y. Omura; M. Ono; R. Onogi; A. Oshima; S. Ozawa; I. H. Park; M. S. Pshirkov; D. C. Rodriguez; G. Rubtsov; D. Ryu; H. Sagawa; R. Sahara; K. Saito; Y. Saito; N. Sakaki; N. Sakurai; L. M. Scott; T. Seki; K. Sekino; P. D. Shah; F. Shibata; T. Shibata; H. Shimodaira; B. K. Shin; H. S. Shin; J. D. Smith; P. Sokolsky; B. T. Stokes; S. R. Stratton; T. A. Stroman; T. Suzawa; Y. Takagi; Y. Takahashi; M. Takamura; R. Takeishi; A. Taketa; M. Takita; Y. Tameda; H. Tanaka; K. Tanaka; M. Tanaka; S. B. Thomas; G. B. Thomson; P. Tinyakov; I. Tkachev; H. Tokuno; T. Tomida; S. Troitsky; Y. Tsunesada; K. Tsutsumi; Y. Uchihori; S. Udo; F. Urban; T. Wong; M. Yamamoto; R. Yamane; H. Yamaoka; K. Yamazaki; J. Yang; K. Yashiro; Y. Yoneda; S. Yoshida; H. Yoshii; Y. Zhezher; Z. Zundel

doi:10.3847/1538-4357/aac9c8

Evidence of Intermediate-scale Energy Spectrum Anisotropy of Cosmic Rays e ≥ 10^19.2 eV with the Telescope Array Surface Detector

R. U. Abbasi, M. Abe, T. Abu-Zayyad, M. Allen, R. Azuma, E. Barcikowski, J. W. Belz, D. R. Bergman, S. A. Blake, R. Cady, B. G. Cheon, J. Chiba, M. Chikawa, A. Di Matteo, T. Fujii, K. Fujita, M. Fukushima, G. Furlich, T. Goto, W. HanlonM. Hayashi, Y. Hayashi, N. Hayashida, K. Hibino, K. Honda, D. Ikeda, N. Inoue, T. Ishii, R. Ishimori, H. Ito, D. Ivanov, H. M. Jeong, S. Jeong, C. C.H. Jui, K. Kadota, F. Kakimoto, O. Kalashev, K. Kasahara, H. Kawai, S. Kawakami, S. Kawana, K. Kawata, E. Kido, H. B. Kim, J. H. Kim, J. H. Kim, S. Kishigami, S. Kitamura, Y. Kitamura, V. Kuzmin, M. Kuznetsov, Y. J. Kwon, K. H. Lee, B. Lubsandorzhiev, J. P. Lundquist, K. Machida, K. Martens, T. Matsuyama, J. N. Matthews, R. Mayta, M. Minamino, K. Mukai, I. Myers, K. Nagasawa, S. Nagataki, R. Nakamura, T. Nakamura, T. Nonaka, A. Nozato, H. Oda, S. Ogio, J. Ogura, M. Ohnishi, H. Ohoka, T. Okuda, Y. Omura, M. Ono, R. Onogi, A. Oshima, S. Ozawa, I. H. Park, M. S. Pshirkov, D. C. Rodriguez, G. Rubtsov, D. Ryu, H. Sagawa, R. Sahara, K. Saito, Y. Saito, N. Sakaki, N. Sakurai, L. M. Scott, T. Seki, K. Sekino, P. D. Shah, F. Shibata, T. Shibata, H. Shimodaira, B. K. Shin, H. S. Shin, J. D. Smith, P. Sokolsky, B. T. Stokes, S. R. Stratton, T. A. Stroman, T. Suzawa, Y. Takagi, Y. Takahashi, M. Takamura, R. Takeishi, A. Taketa, M. Takita, Y. Tameda, H. Tanaka, K. Tanaka, M. Tanaka, S. B. Thomas, G. B. Thomson, P. Tinyakov, I. Tkachev, H. Tokuno, T. Tomida, S. Troitsky, Y. Tsunesada, K. Tsutsumi, Y. Uchihori, S. Udo, F. Urban, T. Wong, M. Yamamoto, R. Yamane, H. Yamaoka, K. Yamazaki, J. Yang, K. Yashiro, Y. Yoneda, S. Yoshida, H. Yoshii, Y. Zhezher, Z. Zundel

Department of Physics

Research output: Contribution to journal › Article › peer-review

30 Citations (Scopus)

Abstract

Evidence for an intermediate-scale energy spectrum anisotropy has been found in the arrival directions of ultra-high energy cosmic rays for energies greater than 10^19.2 eV in the northern hemisphere using 7 years of Telescope Array surface detector data. A relative energy distribution test is done comparing events inside oversampled spherical caps of equal exposure, to those outside, using the Poisson likelihood ratio. The center of maximum significance is at 9^h16^m, 45°, and has a deficit of events with energies 10^19.2 ≤ E < 10^19.75 eV and an excess for E ≥ 10^19.75 eV. The post-trial probability of this energy anisotropy, appearing by chance anywhere on an isotropic sky, is found by Monte Carlo simulation to be 9 10^-5 (3.74σ _global).

Original language	English
Article number	91
Journal	Astrophysical Journal
Volume	862
Issue number	2
DOIs	https://doi.org/10.3847/1538-4357/aac9c8
Publication status	Published - 2018 Aug 1

Bibliographical note

Funding Information:
The Telescope Array is supported by the Japan Society for the Promotion of Science (JSPS) through Grants-in-Aid for Priority Area 431, Specially Promoted Research JP21000002, Scientific Research (S) JP19104006, Specially Promoted Research JP15H05693, Scientific Research (S) JP15H05741 and for Young Scientists (A) JPH26707011; by the joint research program of the Institute for Cosmic Ray Research (ICRR) and the University of Tokyo; by the U.S. National Science Foundation awards PHY-0601915, PHY-1404495, PHY-1404502, and PHY-1607727; by the National Research Foundation of Korea (2016R1 A2B4014967, 2016R1A5A1013277, 2017K1A4A3015188, and 2017R1A2A1A05071429); by the Russian Academy of Sciences, RFBR grant 16-02-00962a (INR), IISN project No. 4.4502.13, and Belgian Science Policy under IUAP VII/37 (ULB). The foundations of Dr. Ezekiel R. and Edna Wattis Dumke, Willard L. Eccles, and George S. and Dolores Doré Eccles all helped with generous donations. The State of Utah provided support through its Economic Development Board, and University of Utah’s Office of the Vice President for Research. The experimental site became available through the cooperation of the Utah School and Institutional Trust Lands Administration (SITLA), U.S. Bureau of Land Management (BLM), and the U.S. Air Force. We appreciate the assistance of the State of Utah and Fillmore offices of the BLM in crafting the Plan of Development for the site. Patrick Shea assisted the collaboration with valuable advice. The people and officials of Millard County, Utah, have provided greatly appreciated steadfast support. We are indebted to the Millard County Road Department for maintenance of the sites roads. We are grateful for the contributions of our home institutions’ technical staffs and the University of Utah Center for High Performance Computing for the allocation of computer time.

Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved.

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.3847/1538-4357/aac9c8

Cite this

Abbasi, R. U., Abe, M., Abu-Zayyad, T., Allen, M., Azuma, R., Barcikowski, E., Belz, J. W., Bergman, D. R., Blake, S. A., Cady, R., Cheon, B. G., Chiba, J., Chikawa, M., Matteo, A. D., Fujii, T., Fujita, K., Fukushima, M., Furlich, G., Goto, T., ... Zundel, Z. (2018). Evidence of Intermediate-scale Energy Spectrum Anisotropy of Cosmic Rays e ≥ 10^19.2 eV with the Telescope Array Surface Detector. Astrophysical Journal, 862(2), Article 91. https://doi.org/10.3847/1538-4357/aac9c8

@article{fa4efdeeac9f4fb0933b74a69cc4cde0,

title = "Evidence of Intermediate-scale Energy Spectrum Anisotropy of Cosmic Rays e ≥ 1019.2 eV with the Telescope Array Surface Detector",

abstract = "Evidence for an intermediate-scale energy spectrum anisotropy has been found in the arrival directions of ultra-high energy cosmic rays for energies greater than 1019.2 eV in the northern hemisphere using 7 years of Telescope Array surface detector data. A relative energy distribution test is done comparing events inside oversampled spherical caps of equal exposure, to those outside, using the Poisson likelihood ratio. The center of maximum significance is at 9h16m, 45°, and has a deficit of events with energies 1019.2 ≤ E < 1019.75 eV and an excess for E ≥ 1019.75 eV. The post-trial probability of this energy anisotropy, appearing by chance anywhere on an isotropic sky, is found by Monte Carlo simulation to be 9 10-5 (3.74σ global).",

author = "Abbasi, {R. U.} and M. Abe and T. Abu-Zayyad and M. Allen and R. Azuma and E. Barcikowski and Belz, {J. W.} and Bergman, {D. R.} and Blake, {S. A.} and R. Cady and Cheon, {B. G.} and J. Chiba and M. Chikawa and Matteo, {A. Di} and T. Fujii and K. Fujita and M. Fukushima and G. Furlich and T. Goto and W. Hanlon and M. Hayashi and Y. Hayashi and N. Hayashida and K. Hibino and K. Honda and D. Ikeda and N. Inoue and T. Ishii and R. Ishimori and H. Ito and D. Ivanov and Jeong, {H. M.} and S. Jeong and Jui, {C. C.H.} and K. Kadota and F. Kakimoto and O. Kalashev and K. Kasahara and H. Kawai and S. Kawakami and S. Kawana and K. Kawata and E. Kido and Kim, {H. B.} and Kim, {J. H.} and Kim, {J. H.} and S. Kishigami and S. Kitamura and Y. Kitamura and V. Kuzmin and M. Kuznetsov and Kwon, {Y. J.} and Lee, {K. H.} and B. Lubsandorzhiev and Lundquist, {J. P.} and K. Machida and K. Martens and T. Matsuyama and Matthews, {J. N.} and R. Mayta and M. Minamino and K. Mukai and I. Myers and K. Nagasawa and S. Nagataki and R. Nakamura and T. Nakamura and T. Nonaka and A. Nozato and H. Oda and S. Ogio and J. Ogura and M. Ohnishi and H. Ohoka and T. Okuda and Y. Omura and M. Ono and R. Onogi and A. Oshima and S. Ozawa and Park, {I. H.} and Pshirkov, {M. S.} and Rodriguez, {D. C.} and G. Rubtsov and D. Ryu and H. Sagawa and R. Sahara and K. Saito and Y. Saito and N. Sakaki and N. Sakurai and Scott, {L. M.} and T. Seki and K. Sekino and Shah, {P. D.} and F. Shibata and T. Shibata and H. Shimodaira and Shin, {B. K.} and Shin, {H. S.} and Smith, {J. D.} and P. Sokolsky and Stokes, {B. T.} and Stratton, {S. R.} and Stroman, {T. A.} and T. Suzawa and Y. Takagi and Y. Takahashi and M. Takamura and R. Takeishi and A. Taketa and M. Takita and Y. Tameda and H. Tanaka and K. Tanaka and M. Tanaka and Thomas, {S. B.} and Thomson, {G. B.} and P. Tinyakov and I. Tkachev and H. Tokuno and T. Tomida and S. Troitsky and Y. Tsunesada and K. Tsutsumi and Y. Uchihori and S. Udo and F. Urban and T. Wong and M. Yamamoto and R. Yamane and H. Yamaoka and K. Yamazaki and J. Yang and K. Yashiro and Y. Yoneda and S. Yoshida and H. Yoshii and Y. Zhezher and Z. Zundel",

note = "Funding Information: The Telescope Array is supported by the Japan Society for the Promotion of Science (JSPS) through Grants-in-Aid for Priority Area 431, Specially Promoted Research JP21000002, Scientific Research (S) JP19104006, Specially Promoted Research JP15H05693, Scientific Research (S) JP15H05741 and for Young Scientists (A) JPH26707011; by the joint research program of the Institute for Cosmic Ray Research (ICRR) and the University of Tokyo; by the U.S. National Science Foundation awards PHY-0601915, PHY-1404495, PHY-1404502, and PHY-1607727; by the National Research Foundation of Korea (2016R1 A2B4014967, 2016R1A5A1013277, 2017K1A4A3015188, and 2017R1A2A1A05071429); by the Russian Academy of Sciences, RFBR grant 16-02-00962a (INR), IISN project No. 4.4502.13, and Belgian Science Policy under IUAP VII/37 (ULB). The foundations of Dr. Ezekiel R. and Edna Wattis Dumke, Willard L. Eccles, and George S. and Dolores Dor{\'e} Eccles all helped with generous donations. The State of Utah provided support through its Economic Development Board, and University of Utah{\textquoteright}s Office of the Vice President for Research. The experimental site became available through the cooperation of the Utah School and Institutional Trust Lands Administration (SITLA), U.S. Bureau of Land Management (BLM), and the U.S. Air Force. We appreciate the assistance of the State of Utah and Fillmore offices of the BLM in crafting the Plan of Development for the site. Patrick Shea assisted the collaboration with valuable advice. The people and officials of Millard County, Utah, have provided greatly appreciated steadfast support. We are indebted to the Millard County Road Department for maintenance of the sites roads. We are grateful for the contributions of our home institutions{\textquoteright} technical staffs and the University of Utah Center for High Performance Computing for the allocation of computer time. Publisher Copyright: {\textcopyright} 2018. The American Astronomical Society. All rights reserved.",

year = "2018",

month = aug,

day = "1",

doi = "10.3847/1538-4357/aac9c8",

language = "English",

volume = "862",

journal = "Astrophysical Journal",

issn = "0004-637X",

publisher = "IOP Publishing Ltd.",

number = "2",

}

Abbasi, RU, Abe, M, Abu-Zayyad, T, Allen, M, Azuma, R, Barcikowski, E, Belz, JW, Bergman, DR, Blake, SA, Cady, R, Cheon, BG, Chiba, J, Chikawa, M, Matteo, AD, Fujii, T, Fujita, K, Fukushima, M, Furlich, G, Goto, T, Hanlon, W, Hayashi, M, Hayashi, Y, Hayashida, N, Hibino, K, Honda, K, Ikeda, D, Inoue, N, Ishii, T, Ishimori, R, Ito, H, Ivanov, D, Jeong, HM, Jeong, S, Jui, CCH, Kadota, K, Kakimoto, F, Kalashev, O, Kasahara, K, Kawai, H, Kawakami, S, Kawana, S, Kawata, K, Kido, E, Kim, HB, Kim, JH, Kim, JH, Kishigami, S, Kitamura, S, Kitamura, Y, Kuzmin, V, Kuznetsov, M, Kwon, YJ, Lee, KH, Lubsandorzhiev, B, Lundquist, JP, Machida, K, Martens, K, Matsuyama, T, Matthews, JN, Mayta, R, Minamino, M, Mukai, K, Myers, I, Nagasawa, K, Nagataki, S, Nakamura, R, Nakamura, T, Nonaka, T, Nozato, A, Oda, H, Ogio, S, Ogura, J, Ohnishi, M, Ohoka, H, Okuda, T, Omura, Y, Ono, M, Onogi, R, Oshima, A, Ozawa, S, Park, IH, Pshirkov, MS, Rodriguez, DC, Rubtsov, G, Ryu, D, Sagawa, H, Sahara, R, Saito, K, Saito, Y, Sakaki, N, Sakurai, N, Scott, LM, Seki, T, Sekino, K, Shah, PD, Shibata, F, Shibata, T, Shimodaira, H, Shin, BK, Shin, HS, Smith, JD, Sokolsky, P, Stokes, BT, Stratton, SR, Stroman, TA, Suzawa, T, Takagi, Y, Takahashi, Y, Takamura, M, Takeishi, R, Taketa, A, Takita, M, Tameda, Y, Tanaka, H, Tanaka, K, Tanaka, M, Thomas, SB, Thomson, GB, Tinyakov, P, Tkachev, I, Tokuno, H, Tomida, T, Troitsky, S, Tsunesada, Y, Tsutsumi, K, Uchihori, Y, Udo, S, Urban, F, Wong, T, Yamamoto, M, Yamane, R, Yamaoka, H, Yamazaki, K, Yang, J, Yashiro, K, Yoneda, Y, Yoshida, S, Yoshii, H, Zhezher, Y & Zundel, Z 2018, 'Evidence of Intermediate-scale Energy Spectrum Anisotropy of Cosmic Rays e ≥ 10^19.2 eV with the Telescope Array Surface Detector', Astrophysical Journal, vol. 862, no. 2, 91. https://doi.org/10.3847/1538-4357/aac9c8

TY - JOUR

T1 - Evidence of Intermediate-scale Energy Spectrum Anisotropy of Cosmic Rays e ≥ 1019.2 eV with the Telescope Array Surface Detector

AU - Abbasi, R. U.

AU - Abe, M.

AU - Abu-Zayyad, T.

AU - Allen, M.

AU - Azuma, R.

AU - Barcikowski, E.

AU - Belz, J. W.

AU - Bergman, D. R.

AU - Blake, S. A.

AU - Cady, R.

AU - Cheon, B. G.

AU - Chiba, J.

AU - Chikawa, M.

AU - Matteo, A. Di

AU - Fujii, T.

AU - Fujita, K.

AU - Fukushima, M.

AU - Furlich, G.

AU - Goto, T.

AU - Hanlon, W.

AU - Hayashi, M.

AU - Hayashi, Y.

AU - Hayashida, N.

AU - Hibino, K.

AU - Honda, K.

AU - Ikeda, D.

AU - Inoue, N.

AU - Ishii, T.

AU - Ishimori, R.

AU - Ito, H.

AU - Ivanov, D.

AU - Jeong, H. M.

AU - Jeong, S.

AU - Jui, C. C.H.

AU - Kadota, K.

AU - Kakimoto, F.

AU - Kalashev, O.

AU - Kasahara, K.

AU - Kawai, H.

AU - Kawakami, S.

AU - Kawana, S.

AU - Kawata, K.

AU - Kido, E.

AU - Kim, H. B.

AU - Kim, J. H.

AU - Kishigami, S.

AU - Kitamura, S.

AU - Kitamura, Y.

AU - Kuzmin, V.

AU - Kuznetsov, M.

AU - Kwon, Y. J.

AU - Lee, K. H.

AU - Lubsandorzhiev, B.

AU - Lundquist, J. P.

AU - Machida, K.

AU - Martens, K.

AU - Matsuyama, T.

AU - Matthews, J. N.

AU - Mayta, R.

AU - Minamino, M.

AU - Mukai, K.

AU - Myers, I.

AU - Nagasawa, K.

AU - Nagataki, S.

AU - Nakamura, R.

AU - Nakamura, T.

AU - Nonaka, T.

AU - Nozato, A.

AU - Oda, H.

AU - Ogio, S.

AU - Ogura, J.

AU - Ohnishi, M.

AU - Ohoka, H.

AU - Okuda, T.

AU - Omura, Y.

AU - Ono, M.

AU - Onogi, R.

AU - Oshima, A.

AU - Ozawa, S.

AU - Park, I. H.

AU - Pshirkov, M. S.

AU - Rodriguez, D. C.

AU - Rubtsov, G.

AU - Ryu, D.

AU - Sagawa, H.

AU - Sahara, R.

AU - Saito, K.

AU - Saito, Y.

AU - Sakaki, N.

AU - Sakurai, N.

AU - Scott, L. M.

AU - Seki, T.

AU - Sekino, K.

AU - Shah, P. D.

AU - Shibata, F.

AU - Shibata, T.

AU - Shimodaira, H.

AU - Shin, B. K.

AU - Shin, H. S.

AU - Smith, J. D.

AU - Sokolsky, P.

AU - Stokes, B. T.

AU - Stratton, S. R.

AU - Stroman, T. A.

AU - Suzawa, T.

AU - Takagi, Y.

AU - Takahashi, Y.

AU - Takamura, M.

AU - Takeishi, R.

AU - Taketa, A.

AU - Takita, M.

AU - Tameda, Y.

AU - Tanaka, H.

AU - Tanaka, K.

AU - Tanaka, M.

AU - Thomas, S. B.

AU - Thomson, G. B.

AU - Tinyakov, P.

AU - Tkachev, I.

AU - Tokuno, H.

AU - Tomida, T.

AU - Troitsky, S.

AU - Tsunesada, Y.

AU - Tsutsumi, K.

AU - Uchihori, Y.

AU - Udo, S.

AU - Urban, F.

AU - Wong, T.

AU - Yamamoto, M.

AU - Yamane, R.

AU - Yamaoka, H.

AU - Yamazaki, K.

AU - Yang, J.

AU - Yashiro, K.

AU - Yoneda, Y.

AU - Yoshida, S.

AU - Yoshii, H.

AU - Zhezher, Y.

AU - Zundel, Z.

N1 - Funding Information: The Telescope Array is supported by the Japan Society for the Promotion of Science (JSPS) through Grants-in-Aid for Priority Area 431, Specially Promoted Research JP21000002, Scientific Research (S) JP19104006, Specially Promoted Research JP15H05693, Scientific Research (S) JP15H05741 and for Young Scientists (A) JPH26707011; by the joint research program of the Institute for Cosmic Ray Research (ICRR) and the University of Tokyo; by the U.S. National Science Foundation awards PHY-0601915, PHY-1404495, PHY-1404502, and PHY-1607727; by the National Research Foundation of Korea (2016R1 A2B4014967, 2016R1A5A1013277, 2017K1A4A3015188, and 2017R1A2A1A05071429); by the Russian Academy of Sciences, RFBR grant 16-02-00962a (INR), IISN project No. 4.4502.13, and Belgian Science Policy under IUAP VII/37 (ULB). The foundations of Dr. Ezekiel R. and Edna Wattis Dumke, Willard L. Eccles, and George S. and Dolores Doré Eccles all helped with generous donations. The State of Utah provided support through its Economic Development Board, and University of Utah’s Office of the Vice President for Research. The experimental site became available through the cooperation of the Utah School and Institutional Trust Lands Administration (SITLA), U.S. Bureau of Land Management (BLM), and the U.S. Air Force. We appreciate the assistance of the State of Utah and Fillmore offices of the BLM in crafting the Plan of Development for the site. Patrick Shea assisted the collaboration with valuable advice. The people and officials of Millard County, Utah, have provided greatly appreciated steadfast support. We are indebted to the Millard County Road Department for maintenance of the sites roads. We are grateful for the contributions of our home institutions’ technical staffs and the University of Utah Center for High Performance Computing for the allocation of computer time. Publisher Copyright: © 2018. The American Astronomical Society. All rights reserved.

PY - 2018/8/1

Y1 - 2018/8/1

N2 - Evidence for an intermediate-scale energy spectrum anisotropy has been found in the arrival directions of ultra-high energy cosmic rays for energies greater than 1019.2 eV in the northern hemisphere using 7 years of Telescope Array surface detector data. A relative energy distribution test is done comparing events inside oversampled spherical caps of equal exposure, to those outside, using the Poisson likelihood ratio. The center of maximum significance is at 9h16m, 45°, and has a deficit of events with energies 1019.2 ≤ E < 1019.75 eV and an excess for E ≥ 1019.75 eV. The post-trial probability of this energy anisotropy, appearing by chance anywhere on an isotropic sky, is found by Monte Carlo simulation to be 9 10-5 (3.74σ global).

AB - Evidence for an intermediate-scale energy spectrum anisotropy has been found in the arrival directions of ultra-high energy cosmic rays for energies greater than 1019.2 eV in the northern hemisphere using 7 years of Telescope Array surface detector data. A relative energy distribution test is done comparing events inside oversampled spherical caps of equal exposure, to those outside, using the Poisson likelihood ratio. The center of maximum significance is at 9h16m, 45°, and has a deficit of events with energies 1019.2 ≤ E < 1019.75 eV and an excess for E ≥ 1019.75 eV. The post-trial probability of this energy anisotropy, appearing by chance anywhere on an isotropic sky, is found by Monte Carlo simulation to be 9 10-5 (3.74σ global).

UR - http://www.scopus.com/inward/record.url?scp=85051504735&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85051504735&partnerID=8YFLogxK

U2 - 10.3847/1538-4357/aac9c8

DO - 10.3847/1538-4357/aac9c8

M3 - Article

AN - SCOPUS:85051504735

SN - 0004-637X

VL - 862

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 2

M1 - 91

ER -