1. Isotropy of Cosmic Rays beyond 10^{20} eV Favors Their Heavy Mass Composition.
- Author
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Abbasi RU, Abe Y, Abu-Zayyad T, Allen M, Arai Y, Arimura R, Barcikowski E, Belz JW, Bergman DR, Blake SA, Buckland I, Cheon BG, Chikawa M, Fujii T, Fujisue K, Fujita K, Fujiwara R, Fukushima M, Furlich G, Globus N, Gonzalez R, Hanlon W, Hayashida N, He H, Hibi R, Hibino K, Higuchi R, Honda K, Ikeda D, Inoue N, Ishii T, Ito H, Ivanov D, Iwasaki A, Jeong HM, Jeong S, Jui CCH, Kadota K, Kakimoto F, Kalashev O, Kasahara K, Kasami S, Kawakami S, Kawata K, Kharuk I, Kido E, Kim HB, Kim JH, Kim JH, Kim SW, Kimura Y, Komae I, Kuzmin V, Kuznetsov M, Kwon YJ, Lee KH, Lubsandorzhiev B, Lundquist JP, Matsumiya H, Matsuyama T, Matthews JN, Mayta R, Mizuno K, Murakami M, Myers I, Lee KH, Nagataki S, Nakai K, Nakamura T, Nishio E, Nonaka T, Oda H, Ogio S, Onishi M, Ohoka H, Okazaki N, Oku Y, Okuda T, Omura Y, Ono M, Oshima A, Oshima H, Ozawa S, Park IH, Park KY, Potts M, Pshirkov MS, Remington J, Rodriguez DC, Rott C, Rubtsov GI, Ryu D, Sagawa H, Saito R, Sakaki N, Sako T, Sakurai N, Sato D, Sato K, Sato S, Sekino K, Shah PD, Shibata N, Shibata T, Shikita J, Shimodaira H, Shin BK, Shin HS, Shinto D, Smith JD, Sokolsky P, Stokes BT, Stroman TA, Takagi Y, Takahashi K, Takamura M, Takeda M, Takeishi R, Taketa A, Takita M, Tameda Y, Tanaka K, Tanaka M, Tanoue Y, Thomas SB, Thomson GB, Tinyakov P, Tkachev I, Tokuno H, Tomida T, Troitsky S, Tsuda R, Tsunesada Y, Udo S, Urban F, Warren D, Wong T, Yamazaki K, Yashiro K, Yoshida F, Zhezher Y, and Zundel Z
- Abstract
We report an estimation of the injected mass composition of ultrahigh energy cosmic rays (UHECRs) at energies higher than 10 EeV. The composition is inferred from an energy-dependent sky distribution of UHECR events observed by the Telescope Array surface detector by comparing it to the Large Scale Structure of the local Universe. In the case of negligible extragalactic magnetic fields (EGMFs), the results are consistent with a relatively heavy injected composition at E∼10 EeV that becomes lighter up to E∼100 EeV, while the composition at E>100 EeV is very heavy. The latter is true even in the presence of highest experimentally allowed extragalactic magnetic fields, while the composition at lower energies can be light if a strong EGMF is present. The effect of the uncertainty in the galactic magnetic field on these results is subdominant.
- Published
- 2024
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