The Anisotropy of Cosmic Ray Arrival Direction around 10^18eV
Abstract
Anisotropy in the arrival directions of cosmic rays around 10^{18}eV is studied using data from the Akeno 20 km^2 array and the Akeno Giant Air Shower Array (AGASA), using a total of about 216,000 showers observed over 15 years above 10^{17}eV. In the first harmonic analysis, we have found significant anisotropy of 4 % around 10^{18}eV, corresponding to a chance probability of after taking the number of independent trials into account. With two dimensional analysis in right ascension and declination, this anisotropy is interpreted as an excess of showers near the directions of the Galactic Center and the Cygnus region. This is a clear evidence for the existence of the galactic cosmic ray up to the energy of 10^{18}eV. Primary particle which contribute this anisotropy may be proton or neutron.
Keywords
Cite
@article{arxiv.astro-ph/9906056,
title = {The Anisotropy of Cosmic Ray Arrival Direction around 10^18eV},
author = {N. Hayashida and K. Honda and N. Inoue and K. Kadota and F. Kakimoto and S. Kakizawa and K. Kamata and S. Kawaguchi and Y. Kawasaki and N. Kawasumi and E. Kusano and Y. Matsubara and K. Mase and T. Minagawa and K. Murakami and M. Nagano and D. Nishikawa and H. Ohoka and S. Osone and N. Sakaki and M. Sasaki and M. Sasano and K. Shinozaki and M. Takeda and M. Teshima and R. Torii and I. Tsushima and Y. Uchihori and T. Yamamoto and S. Yoshida and H. Yoshii and The AGASA Collaboration},
journal= {arXiv preprint arXiv:astro-ph/9906056},
year = {2009}
}
Comments
4pages, three figures, to appear in Procedings of 26th ICRC(Salt Lake City)