Is the large-scale sidereal anisotropy of the galactic cosmic-ray intensity really instable at TeV energies?

M. Amenomori, X. J. Bi, D. Chen, W. Y. Chen, S. W. Cui, Danzengluobu, L. K. Ding, X. H. Ding, C. F. Feng, Zhaoyang Feng, Z. Y. Feng, Q. B. Gou, H. W. Guo, Y. Q. Guo, H. H. He, Z. T. He, K. Hibino, N. Hotta, Haibing Hu, H. B. HuJ. Huang, H. Y. Jia, L. Jiang, F. Kajino, K. Kasahara, Y. Katayose, C. Kato, K. Kawata, Labaciren, G. M. Le, A. F. Li, W. J. Li, C. Liu, J. S. Liu, H. Lu, X. R. Meng, K. Mizutani, K. Munakata, H. Nanjo, M. Nishizawa, M. Ohnishi, I. Ohta, Shunsuke Ozawa, X. L. Qian, X. B. Qu, T. Saito, T. Y. Saito, M. Sakata, T. K. Sako, J. Shao, M. Shibata, A. Shiomi, T. Shirai, H. Sugimoto, M. Takita, Y. H. Tan, N. Tateyama, Shoji Torii, H. Tsuchiya, S. Udo, H. Wang, H. R. Wu, L. Xue, Y. Yamamoto, Z. Yang, S. Yasue, A. F. Yuan, T. Yuda, L. M. Zhai, H. M. Zhang, J. L. Zhang, X. Y. Zhang, Y. Zhang, Yi Zhang, Ying Zhang, Zhaxisangzhu, X. X. Zhou

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Abstract

The sidereal cosmic-ray anisotropy at TeV energies has a large-scale deficit region distributed between 150 and 240 degrees in right ascension, which is called the "loss-cone". The Milagro experiment reported the detection of a steady increase in the loss-cone amplitude at 6 TeV from July 2000 to July 2007. In this paper, we examine Milagro's claim using the data collected by the Tibet air-shower experiment from November 1999 through December 2008. No time dependence was found in the loss-cone amplitude at 4.4, 6.2, and 11 TeV. If the increase in the loss-cone amplitude were, as Milagro argued, due to variations in the heliosphere in relation to solar activities, the same tendency would be seen at sub-TeV energies where the anisotropy is far more sensitive to solar activities. At 0.6 TeV, however, Matsushiro underground muon observatory reported no significant increase in the loss-cone amplitude during the corresponding period.

Original languageEnglish
Pages (from-to)237-241
Number of pages5
JournalAstroparticle Physics
Volume36
Issue number1
DOIs
Publication statusPublished - 2012 Aug

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Keywords

  • Loss-cone
  • Sidereal cosmic-ray anisotropy
  • TeV

ASJC Scopus subject areas

  • Astronomy and Astrophysics

Cite this

Amenomori, M., Bi, X. J., Chen, D., Chen, W. Y., Cui, S. W., Danzengluobu, Ding, L. K., Ding, X. H., Feng, C. F., Feng, Z., Feng, Z. Y., Gou, Q. B., Guo, H. W., Guo, Y. Q., He, H. H., He, Z. T., Hibino, K., Hotta, N., Hu, H., ... Zhou, X. X. (2012). Is the large-scale sidereal anisotropy of the galactic cosmic-ray intensity really instable at TeV energies? Astroparticle Physics, 36(1), 237-241. https://doi.org/10.1016/j.astropartphys.2012.06.005