Testing a Reported Correlation between Arrival Directions of Ultra-high-energy Cosmic Rays and a Flux Pattern from nearby Starburst Galaxies using Telescope Array Data

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; 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; J. Remington; 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; M. Takeda; 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:10.3847/2041-8213/aaebf9

Testing a Reported Correlation between Arrival Directions of Ultra-high-energy Cosmic Rays and a Flux Pattern from nearby Starburst Galaxies using Telescope Array Data

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, 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, J. Remington, 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, M. Takeda, 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

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37 Citations (Scopus)

Abstract

The Pierre Auger Collaboration (Auger) recently reported a correlation between the arrival directions of cosmic rays with energies above 39 EeV and the flux pattern of 23 nearby starburst galaxies (SBGs). In this Letter, we tested the same hypothesis using cosmic rays detected by the Telescope Array experiment (TA) in the 9 yr period from 2008 May to 2017 May. Unlike the Auger analysis, we did not optimize the parameter values but kept them fixed to the best-fit values found by Auger, namely 9.7% for the anisotropic fraction of cosmic rays assumed to originate from the SBGs in the list and 12.°9 for the angular scale of the correlations. The energy threshold that we adopted is 43 EeV, corresponding to 39 EeV in Auger when taking into account the energy-scale difference between two experiments. We find that the TA data is compatible with isotropy to within 1.1σ and with the Auger result to within 1.4σ, meaning that it is not capable to discriminate between these two hypotheses.

Original language	English
Article number	L27
Journal	Astrophysical Journal Letters
Volume	867
Issue number	2
DOIs	https://doi.org/10.3847/2041-8213/aaebf9
Publication status	Published - 2018 Nov 10

Bibliographical note

Funding Information:
The Telescope Array experiment is supported by the Japan Society for the Promotion of Science (JSPS) through Grants-in-Aid for Priority Area 431, for Specially Promoted Research JP21000002, for Scientific Research (S) JP19104006, for Specially Promoted Research JP15H05693, for Scientific Research (S) JP15H05741 and for Young Scientists (A) JPH26707011; by the joint research program of the Institute for Cosmic Ray Research (ICRR), 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 (2016R1A2B4014967, 2016R1A5A1013277, 2017K1A4A3015188, 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 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 supported the project through its Economic Development Board, and the University of Utah through the 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 on a variety of topics. The people and the officials of Millard County, Utah have been a source of steadfast and warm support for our work which we greatly appreciate. We are indebted to the Millard County Road Department for their efforts to maintain and clear the roads that get us to our sites. We gratefully acknowledge the contribution from the technical staffs of our home institutions. An allocation of computer time from the Center for High Performance Computing at the University of Utah is gratefully acknowledged.

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

All Science Journal Classification (ASJC) codes

Astronomy and Astrophysics
Space and Planetary Science

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10.3847/2041-8213/aaebf9

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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). Testing a Reported Correlation between Arrival Directions of Ultra-high-energy Cosmic Rays and a Flux Pattern from nearby Starburst Galaxies using Telescope Array Data. Astrophysical Journal Letters, 867(2), [L27]. https://doi.org/10.3847/2041-8213/aaebf9

@article{0ce8f4a70bad4bd4975960d5dc51f992,

title = "Testing a Reported Correlation between Arrival Directions of Ultra-high-energy Cosmic Rays and a Flux Pattern from nearby Starburst Galaxies using Telescope Array Data",

abstract = "The Pierre Auger Collaboration (Auger) recently reported a correlation between the arrival directions of cosmic rays with energies above 39 EeV and the flux pattern of 23 nearby starburst galaxies (SBGs). In this Letter, we tested the same hypothesis using cosmic rays detected by the Telescope Array experiment (TA) in the 9 yr period from 2008 May to 2017 May. Unlike the Auger analysis, we did not optimize the parameter values but kept them fixed to the best-fit values found by Auger, namely 9.7% for the anisotropic fraction of cosmic rays assumed to originate from the SBGs in the list and 12.°9 for the angular scale of the correlations. The energy threshold that we adopted is 43 EeV, corresponding to 39 EeV in Auger when taking into account the energy-scale difference between two experiments. We find that the TA data is compatible with isotropy to within 1.1σ and with the Auger result to within 1.4σ, meaning that it is not capable to discriminate between these two hypotheses.",

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 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 J. Remington 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 M. Takeda 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 experiment is supported by the Japan Society for the Promotion of Science (JSPS) through Grants-in-Aid for Priority Area 431, for Specially Promoted Research JP21000002, for Scientific Research (S) JP19104006, for Specially Promoted Research JP15H05693, for Scientific Research (S) JP15H05741 and for Young Scientists (A) JPH26707011; by the joint research program of the Institute for Cosmic Ray Research (ICRR), 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 (2016R1A2B4014967, 2016R1A5A1013277, 2017K1A4A3015188, 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 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 supported the project through its Economic Development Board, and the University of Utah through the 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 on a variety of topics. The people and the officials of Millard County, Utah have been a source of steadfast and warm support for our work which we greatly appreciate. We are indebted to the Millard County Road Department for their efforts to maintain and clear the roads that get us to our sites. We gratefully acknowledge the contribution from the technical staffs of our home institutions. An allocation of computer time from the Center for High Performance Computing at the University of Utah is gratefully acknowledged. Publisher Copyright: {\textcopyright} 2018. The American Astronomical Society. All rights reserved..",

year = "2018",

month = nov,

day = "10",

doi = "10.3847/2041-8213/aaebf9",

language = "English",

volume = "867",

journal = "Astrophysical Journal Letters",

issn = "2041-8205",

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, 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, Remington, J, 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, Takeda, 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, 'Testing a Reported Correlation between Arrival Directions of Ultra-high-energy Cosmic Rays and a Flux Pattern from nearby Starburst Galaxies using Telescope Array Data', Astrophysical Journal Letters, vol. 867, no. 2, L27. https://doi.org/10.3847/2041-8213/aaebf9

TY - JOUR

T1 - Testing a Reported Correlation between Arrival Directions of Ultra-high-energy Cosmic Rays and a Flux Pattern from nearby Starburst Galaxies using Telescope Array Data

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 - 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 - Remington, J.

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 - Takeda, 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 experiment is supported by the Japan Society for the Promotion of Science (JSPS) through Grants-in-Aid for Priority Area 431, for Specially Promoted Research JP21000002, for Scientific Research (S) JP19104006, for Specially Promoted Research JP15H05693, for Scientific Research (S) JP15H05741 and for Young Scientists (A) JPH26707011; by the joint research program of the Institute for Cosmic Ray Research (ICRR), 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 (2016R1A2B4014967, 2016R1A5A1013277, 2017K1A4A3015188, 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 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 supported the project through its Economic Development Board, and the University of Utah through the 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 on a variety of topics. The people and the officials of Millard County, Utah have been a source of steadfast and warm support for our work which we greatly appreciate. We are indebted to the Millard County Road Department for their efforts to maintain and clear the roads that get us to our sites. We gratefully acknowledge the contribution from the technical staffs of our home institutions. An allocation of computer time from the Center for High Performance Computing at the University of Utah is gratefully acknowledged. Publisher Copyright: © 2018. The American Astronomical Society. All rights reserved..

PY - 2018/11/10

Y1 - 2018/11/10

N2 - The Pierre Auger Collaboration (Auger) recently reported a correlation between the arrival directions of cosmic rays with energies above 39 EeV and the flux pattern of 23 nearby starburst galaxies (SBGs). In this Letter, we tested the same hypothesis using cosmic rays detected by the Telescope Array experiment (TA) in the 9 yr period from 2008 May to 2017 May. Unlike the Auger analysis, we did not optimize the parameter values but kept them fixed to the best-fit values found by Auger, namely 9.7% for the anisotropic fraction of cosmic rays assumed to originate from the SBGs in the list and 12.°9 for the angular scale of the correlations. The energy threshold that we adopted is 43 EeV, corresponding to 39 EeV in Auger when taking into account the energy-scale difference between two experiments. We find that the TA data is compatible with isotropy to within 1.1σ and with the Auger result to within 1.4σ, meaning that it is not capable to discriminate between these two hypotheses.

AB - The Pierre Auger Collaboration (Auger) recently reported a correlation between the arrival directions of cosmic rays with energies above 39 EeV and the flux pattern of 23 nearby starburst galaxies (SBGs). In this Letter, we tested the same hypothesis using cosmic rays detected by the Telescope Array experiment (TA) in the 9 yr period from 2008 May to 2017 May. Unlike the Auger analysis, we did not optimize the parameter values but kept them fixed to the best-fit values found by Auger, namely 9.7% for the anisotropic fraction of cosmic rays assumed to originate from the SBGs in the list and 12.°9 for the angular scale of the correlations. The energy threshold that we adopted is 43 EeV, corresponding to 39 EeV in Auger when taking into account the energy-scale difference between two experiments. We find that the TA data is compatible with isotropy to within 1.1σ and with the Auger result to within 1.4σ, meaning that it is not capable to discriminate between these two hypotheses.

UR - http://www.scopus.com/inward/record.url?scp=85056726429&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85056726429&partnerID=8YFLogxK

U2 - 10.3847/2041-8213/aaebf9

DO - 10.3847/2041-8213/aaebf9

M3 - Article

AN - SCOPUS:85056726429

SN - 2041-8205

VL - 867

JO - Astrophysical Journal Letters

JF - Astrophysical Journal Letters

IS - 2

M1 - L27

ER -

Testing a Reported Correlation between Arrival Directions of Ultra-high-energy Cosmic Rays and a Flux Pattern from nearby Starburst Galaxies using Telescope Array Data

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