An extremely energetic cosmic ray observed by a surface detector array
R. U. Abbasi, M. Allen, R. Arimura, John Belz, D. R. Bergman, S. A. Blake, B. K. Shin, I. J. Buckland, B. G. Cheon, Toshihiro Fujii, Kozo Fujisue, K. Fujita, M. Fukushima, Greg Furlich, Z. Gerber, Noémie Globus, K. Hibino, Ryo Higuchi, K. Honda, D. Ikeda, Hirotaka Ito, Aoi Iwasaki, S. Jeong, H. M. Jeong, Charles Jui, K. Kadota, F. Kakimoto, O. Kalashev, K. Kasahara, K. Kawata, Ivan Kharuk, E. Kido, S. W. Kim, Jihyun Kim, Jihyun Kim, Jihyun Kim, I. Komae, Yuto Kubota, M. Kuznetsov, K. H. Lee, Б. К. Лубсандоржиев, Jon Paul Lundquist, J. N. Matthews, S. Nagataki, Tomohiko Nakamura, Arata Nakazawa, T. Nonaka, S. Ogio, M. Ono, H. Oshima, Il Han Park, M. Potts, S. Pshirkov, Jackson Remington, D. Rodriguez, C. Rott, Г. И. Рубцов, Dongsu Ryu, H. Sagawa, Н. Сакаки, T. Sako, N. Sakurai, Han‐Back Shin, J. D. Smith, P. Sokolsky, B. T. Stokes, T. S. Stroman, Kazuaki Takahashi, M. Takeda, A. Taketa, Y. Tameda, S. B. Thomas, G. B. Thomson, P. Tinyakov, I. Tkachev, T. Tomida, S. Troitsky, Y. Tsunesada, S. Udo, F. Urban, Tiffany Wong, K. Yamazaki, Yasuko Yuma, Yana Zhezher, Z. Zundel
Abstract
Cosmic rays are energetic charged particles from extraterrestrial sources, with the highest-energy events thought to come from extragalactic sources. Their arrival is infrequent, so detection requires instruments with large collecting areas. In this work, we report the detection of an extremely energetic particle recorded by the surface detector array of the Telescope Array experiment. We calculate the particle's energy as [Formula: see text] (~40 joules). Its arrival direction points back to a void in the large-scale structure of the Universe. Possible explanations include a large deflection by the foreground magnetic field, an unidentified source in the local extragalactic neighborhood, or an incomplete knowledge of particle physics.