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Coexistence of cosmic-ray sidereal anisotropies originating in galactic space and at the heliomagnetospheric nose and tail boundaries, observed with muon detectors in the energy region of 60100 GeV

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Abstract

The coexistence of two kinds of cosmic-ray sidereal anisotropy was found by observations with underground muon telescopes in the energy region (> 200 GeV) in 1995: one is the galactic anisotropy with a deficit flux in the direction with right ascension α G = 12 hr and declination δ G = 20°. The other is the excess flux from the heliomagnetospheric tail direction (α T 6 hr) and would be produced on the heliotail boundary where it is considered that the interaction between the galactic and solar magnetic fields could produce the cosmic-ray acceleration. On the other hand, another anisotropy of helioboundary origin from the helionose direction (α 18 hr), being accompanied by the heliotail-in anisotropy, was found through the observations with neutron monitors in the low energy region (20 GeV) in 2005. These observations, however, lack information in the mid-energy region (20200 GeV). In order to bridge the absence of information, the cosmic-ray sidereal daily variations in the energy regions (60100 GeV) have been derived from the observations with muon telescopes and ion chambers on the ground in the period 1936–2003. It is shown that all the three anisotropies coexist in this energy region and are subject to their respective solar modulations. On the basis of these modulations, the characteristics of the anisotropies are determined through intercomparison with the observations in the high and low energy regions.

References

  1. Ajello, J.M., An interpretation ofMariner 10 helium(584 Å) and hydrogen (1216 Å) interplanetary emission observations. Astrophys. J.222, 1068–1078, 1978.

  2. Beach, L. and S. E. Forbush, Cosmic-ray Results, Publ. 175, Vol. XXI, Carnegie Inst. of Washington, Washington, D.C., 1961.

  3. Campbel, W. W., and J. H. Moore, Publ. Lick Obs., 16, 38, 1928.

  4. Fujii, Z., S. Sakakibara, K. Fujimoto, and H. Ueno, Multi-directional Cosmic-ray Intensities, Nagoya, Report of Cosmic-Ray Research Laboratory, No. 15, Cosmic-Ray Research Laboratory, Nagoya Univ., Nagoya, Japan, 1990.

  5. Fujii, Z., S. Sakakibara, K. Fujimoto, H. Ueno, M. Orito, and T. Yamada, Multi-directional cosmic-ray intensities, Nagoya, Report of Cosmic-Ray Research Section, Nos. 17, 18, Cosmic-Ray Research Section, Solar- Terrestrial Environment Laboratory, Nagoya Univ., Nagoya, Japan, 1993, 1996.

  6. Fujii, Z., S. Sakakibara, K. Fujimoto, M. Orito, and T. Yamada, Multidirectional cosmic-ray intensities, Nagoya, Report of Cosmic-Ray Research Section, No. 19, Cosmic-Ray Research Section, Solar-Terrestrial Environment Laboratory, Nagoya Univ., Nagoya, Japan, 2000.

  7. Fujimoto, K., A. Inoue, K. Murakami, and K. Nagashima, Coupling coefficients of cosmic-ray daily variations for muon telescopes, Report of Cosmic-Ray Research Laboratory, No. 9, Cosmic-Ray Research Laboratory, Nagoya Univ., Nagoya, Japan, 1984.

  8. Howard, R., Studies of solar magnetic fields I: The average field strength. Solar Phys.38, 283–299, 1974.

  9. Inoue, A., M. Wada, and K. Kondo, Asymptotic direction in 1975, Cosmic Ray Table, No. 1, WDC-C2 for Cosmic Rays, Institute of Phys. and Chem. Res., Tokyo, 1983.

  10. Jacklyn, R. M., Galactic cosmic ray anisotropies in the energy range 1011–1014 eV., Proc. Astron. Soc. Australia, 6, 425–436, 1986.

  11. Lange, I. and S. E. Forbush, Cosmic-ray results, Publ. 175, Vol. XIV, Carnegie Inst. of Washington, Washington, D.C., 1948.

  12. Lange, I. and S. E. Forbush, Cosmic-ray results, Publ. 175, Vol. XX, Carnegie Inst. of Washington, Washington, D.C., 1957.

  13. McClintock, W., R. Henry, J. L. Linsky, and H. Moos, Ultraviolet observations of cool stars, II. Local interstellar hydrogen and deuterium Lymanalpha. Astrophys. J., 225, 465–481, 1978.

  14. Nagashima, K., Z. Fujii, S. Sakakibara, K. Fujimoto, and H. Ueno, Multidirectional cosmic-ray intensities, Nagoya, Report of Cosmic-Ray Research Laboratory, Nos. 3, 4, 10, 11, Cosmic-Ray Research Laboratory, Nagoya Univ., Nagoya, Japan, 1978 (No. 3), 1981a (No. 4), 1984 (No. 10), 1987 (No. 11).

  15. Nagashima, K. and I. Morishita, Cosmic ray sidereal daily variation of galactic origin observable in heliomagnetosphere, Report of Cosmic- Ray Research Laboratory, Nagoya Univ., Nagoya, Japan, No. 8, 1983.

  16. Nagashima, K., I. Morishita, and S. Yasue, Asymptotic orbit of cosmic rays incident on the Earth from galactic space, Proc. 17th International Cosmic Ray Conference, 4, 189–192, 1981b.

  17. Nagashima, K., I. Morishita, and S. Yasue, Modulation of galactic cosmic ray anisotropy in the heliomagnetosphere: Average sidereal daily variation, Planet. Space Sci., 30, 879–896, 1982.

  18. Nagashima, K., K. Fujimoto, S. Sakakibara, Z. Fujii, H. Ueno, I. Morishita, and K. Murakami, Galactic cosmic-ray anisotropy and its modulation in the heliomagnetosphere, inferred from air shower observation at Mt. Norikura, Nuovo Cimento, 12C, No. 6, 695–749, 1989.

  19. Nagashima, K., K. Fujimoto, and R. M. Jacklyn, Cosmic ray sidereal daily variation showing the coexistence of the galactic and heliomagnetotailin anisotropies, Proc. 24th International Cosmic Ray Conference, 4, 652–655, 1995a.

  20. Nagashima, K., K. Fujimoto, and R. M. Jacklyn, Cosmic ray excess flux from heliomagnetotail, Proc. 24th International Cosmic Ray Conference, 4, 656–659, 1995b.

  21. Nagashima, K., K. Fujimoto, and R. M. Jacklyn, Galactic and heliotail-in anisotropies of cosmic rays as the origin of sidereal daily variation in the energy region < 104 GeV, J. Geophys. Res.103, 17429–17440, 1998.

  22. Nagashima, K., Z. Fujii, and K. Munakata, Solar modulation of galactic and heliotail-in anisotropies of cosmic rays at Sakashita underground station (320650 GeV), Earth Planets Space, 56, 479–483, 2004.

  23. Nagashima, K., I. Kondo, and Z. Fujii, Sharply concentrated cosmic-ray excess fluxes from heliomagnetoshperic nose and tail boundaries observed with neutron monitors on the ground, Earth Planets Space, 57, 1083–1091, 2005.

  24. Sekido, Y., K. Nagashima, I. Kondo, H. Ueno, K. Fujimoto, and Z. Fujii, Multi-directional cosmic-ray intensities, Nagoya, Report of Cosmic-Ray Research Laboratory, No. 1, Cosmic-Ray Research Laboratory, Nagoya Univ., Nagoya, Japan, 1975.

  25. Shafer, G. B. and Yu. G. Shafer, Precise observation of cosmic rays at Yakutsk, Institute of Cosmophysical Research and Aeronomy, Yakutsk, Science Academy of USSR, 1984.

  26. Yasue, S., S. Mori, S. Sakakibara, and K. Nagashima, Coupling coefficients of cosmic ray daily variations for neutron monitor stations, Report of Cosmic-Ray Research Laboratory, No. 7, Cosmic-Ray Research Laboratory, Nagoya Univ., Nagoya, Japan, 1982.

  27. Yasue, S., I. Morishita, and K. Nagashima, Modulation of galactic cosmic ray anisotropy in heliomagnetosphere: influence of cosmic ray scattering on sidereal daily variation, Planet. Space Sci., 33, 1057–1068, 1985.

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Correspondence to K. Nagashima.

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Nagashima, K., Fujii, Z. Coexistence of cosmic-ray sidereal anisotropies originating in galactic space and at the heliomagnetospheric nose and tail boundaries, observed with muon detectors in the energy region of 60100 GeV. Earth Planet Sp 58, 1487–1498 (2006) doi:10.1186/BF03352648

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Key words

  • Cosmic-ray sidereal anisotropy
  • heliomagnetosphere (HMS)
  • boundary of HMS
  • polarity of HMS
  • solar modulation