宗像/一起

南北両半球観測による宇宙線恒星時日変化の解析

Munakata/Kazuoki

Gaussian analysis of two hemisphere observations of galactic cosmic ray sidereal anisotropies









著者名 Authors 所属機関名 所属機関名(欧文)
1 #宗像/一起 Munakata/Kazuoki 信州大学理学部 Faculty of Science, Shinshu University
3 安江/新一 Tanaka/T. 信州大学理学部 Faculty of Science, Shinshu University
4 森/覚 Mori/S. 信州大学理学部 Faculty of Science, Shinshu University
5 加藤/千尋 Kato/C. 信州大学理学部 Faculty of Science, Shinshu University
6 藤井/善次郎 Fujii/Z. 名古屋大学太陽地球環境研究所 STE-lab., Nagoya University
7 藤本/和彦 Fujimoto/K. 名古屋大学太陽地球環境研究所 STE-lab., Nagoya University
8 鷲見/治一 Washimi/H. 湘南工科大学 Shonan Institute of Technology
9 田中/高史 Shonan Institute of Technology 通信総合研究所 Communication Research Laboratory
12 両半球観測グループ two hemisphere observation group K12 M

講演予稿:
 宇宙線強度変動の南北両半球観測結果を、「ロスーコーン」と「テールー イン」異方性を表すガウス関数を用いて解析し、得られたガウス関数の パラメータから、宇宙線恒星時異方性のモデルを導く。また、この異方性の 起源を調べるため、鷲見ー田中(1996)によるMHDシミュレーション 結果を用い、モデル太陽圏内での宇宙線伝播を解析する。

abstract:
 We have analyzed the yearly averaged sidereal daily variations in the count rates of 46 underground muon telescopes by fitting Gaussian functions to the data. These functions represent the Loss-cone and Tail-in anisotropies of the recent sidereal anisotropies model proposed by Nagashima et al. (1995a, 1995b). The underground muon telescopes cover the median rigidity range 143 GV-1400 GV and almost entire celestial sphere. From the Gaussian amplitudes and positions, we have confirmed that the Tail-in anisotropy is more prominent in the southern hemisphere with its reference axis located at declination (delta) ~ 14 deg. south, and right ascention (alpha) ~ 4.7 sidereal hours. The Tail-in anisotropy is asymmetric about its reference axis and the observed time of maximum intensity depends on the viewing latitude of the underground muon telescopes. We also find that the declination of the reference axis may be related to the rigidity of the cosmic rays. We show that the Loss-cone anisotropy is symmetric and has a reference axis located on the celestial equator (delta ~ 0 deg.) and alpha ~ 13 sidereal hours. We have used the parameters of the Gaussian fits to devise an empirical model of the sidereal anisotropies. We present these results and discuss them in relation to the model heliosphere obtained from the three dimensional MHD simulations of the interaction between the solar wind plasma and the interstellar medium by Washimi and Tanaka (1996).

キーワード:
銀河宇宙線、恒星時異方性、外部太陽圏

Keywords:
galactic cosmic-rays, sidereal anisotropy, outer heliosphere