(Tibet AS collaboration) 6th IGPP meeting in Hawaii: March 21, 2007 Implication of the sidereal anisotropy of ~10 TeV (1013 eV) cosmic ray intensity observed with the Tibet III air shower array M. Amenomori, S. Ayabe, X. J. Bi, D. Chen, S. W. Cui, Danzengluobu, L. K. Ding, X. H. Ding, C. F. Feng, Zhaoyang Feng, Z. Y. Feng, X. Y. Gao, Q. X. Geng, H. W. Guo, H. H. He, M. He, K. Hibino, N. Hotta, Haibing Hu, H. B. Hu, J. Huang, Q. Huang, H. Y. Jia, F. Kajino, K. Kasahara, Y. Katayose, C. Kato, K. Kawata, Labaciren, G. M. Le, A. F. Li, J. Y. Li, Y.-Q. Lou, H. Lu, S. L. Lu, X. R. Meng, K. Mizutani, J. Mu, K. Munakata, A. Nagai, H. Nanjo, M. Nishizawa, M. Ohnishi, I. Ohta, H. Onuma, T. Ouchi, S. Ozawa, J. R. Ren, T. Saito, T. Y. Saito, M. Sakata, T. K. Sako, T. Sasaki, M. Shibata, A. Shiomi, T. Shirai, H. Sugimoto, M. Takita, Y. H. Tan, N. Tateyama, S. Torii, H. Tsuchiya, S. Udo, B. Wang, H. Wang, X. Wang, Y. G. Wang, H. R. Wu, L. Xue, Y. Yamamoto, C. T. Yan, X. C. Yang, S. Yasue, Z. H. Ye, G. C. Yu, A. F. Yuan, T. Yuda, H. M. Zhang, J. L. Zhang, N. J. Zhang, X. Y. Zhang, Y. Zhang, Yi Zhang, Zhaxisangzhu and X. X. Zhou (Tibet AS collaboration) 85 people from 25 institutes in Japan and China

Cosmic ray observation with AS array Neutron monitor Muon detector Air shower array 1ry g Ground-based detectors measure byproducts of the interaction of primary cosmic rays (mostly protons) with Earth’s atmosphere. AS array measures electromagnetic component in the cascade shower. AS array also responds to 1ry g-rays, while the muon detector respond only to 1ry protons.

Tibet ASγ experiment Tibet@China Yangbajing 90゜53E, 30゜11N 4,300 m a.s.l. Lasa ~300 km Tibet@China 無断転載禁止 http://www5b.biglobe.ne.jp/~Ken-Road/Tibet/Map/Lhasa.html http://www3.aa.tufs.ac.jp/%7Ehoshi/cgi-bin/dictionary/TJmap.html

Resolving the incident direction trigger rate ~ 680 Hz angular res. ~ 1 533 counters of 0.5 m2 each placed on a 7.5mx7.5m square grid 22,050 m2 detection area Achieved… Highest statistics & Best angular resolution in multi-TeV region

Sidereal anisotropy on the spinning Earth d=30.1o d=90o The zenith direction at Yanbajing is d=30.1o. ● With the spin of Earth, the zenith direction travels along d=30.1o . ● Fixed direction in the horizontal coordinate travels along d=const. for 360o of right ascension once every one sidereal day. ● ● AS flux varies for more than an order of magnitude with the zenith angle due to the different atmospheric depth. The average flux in each d-band is subtracted.

Bi-directional + Uni-directional 2D sky map of CR intensity by Tibet AS (Amenomori et al., Science, 314, 2006) Geographical equator Galactic plane right ascension (º) declination (º) Nose direction “Normalized” intensity map (5°x5° pixels) ~120° 90° < 120° < 180° Bi-directional + Uni-directional Significance map

LIC (Local Interstellar Cloud) RL~ 0.01pc (for 10TeV p in 1mG) Dist. to LIC boundary ~26km/s3000y =0.08pc Probably within 1 m.f.p. in the weak scattering regime T~7000K, nH~0.1/cc Ionization rate~0.52 H Redfield & Linsky, ApJ, 535, 2000 2 pc l=90 He Lallement’s Interstellar B plane (Lallement et al., Science, 307, 2005) l=180 GC lB= 205~240 bB= -38~-60 (or the opposite direction) l=270

LIMC (Local Interstellar Magnetic Cloud) model If cosmic ray density (n) is lower inside LIC than outside…. LIC n High Uni-directional flow (Bxn) n Low G cloud n 26 km/s Bi-directional flow Interstellar B 29 km/s

Best-fitting (preliminary) (DI/I)cal = a1cos1(a1, d1) : Uni-directional + a2+cos2 2(a2, d2) for 0 2/2 + a2-cos2 2(a2, d2) for /2 2  1, 2 : angles from reference axes First choose orientations of reference axes… a1, a2 & d2 (or d1): (a2, d2)  (a1, d1) then a1, a2+ & a2- are given by linear LSM. d.o.f. with 6 free parameters is large as… 90x360/(5x5)-6=1,290 : Bi-directional Result: Uni-directional Bi-directional a1=0.0016, a2+=0.0018, a2-=0.0010 a1=27.5, d1=47.5, a2=97.4, d2=-17.5

“Normalized” intensity (average over dec.-band is subtracted) Best-fit intensity distribution “Normalized” intensity (average over dec.-band is subtracted) Original intensity Uni-direct. + Bi-direct. = Sum

Best-fit performance observation model residual Mrk421 Crab Cygnus region observation model residual (obs.-model)/error Large-scale feature is well reproduced.　2/d.o.f. = 2.493 (“Trough”, “Peak” and broad enhancement around Cygnus region) “Skewed” profile of “Peak” needs to be modeled further.

Comparison with UG-m in two-hemispheres UG-m in Japan V (35°N) Tibet AS UG-m in Tasmania N (4°N) UG-m in Tasmania V (36°S) Tibet AS experiment cannot observe southern hemisphere. : LIMC model (Tibet AS) UG-m @0.5 TeV Hall et al., JGR, 103, 1998 &104, 1999) : Lallement’s B Best-fit B direction may be different when unbiased, by properly taking account of the data in southern hemisphere.

Summary Original intensity map (in galactic coordinate) + - + Large-scale feature of 2D-sky map is well reproduced by the model. (“Trough”, “Peak” and broad enhancement around Cygnus region) “Skewed” profile of the observed “Peak” needs to be modeled further. The model may be biased by the lack of southern hemisphere data. Best-fit B-orientation is in a reasonable agreement with Lallement et al. (2005). Original intensity map (in galactic coordinate) + - -0.0016 +0.0016 +0.0018 +0.0010 l (°) b (°) : heliotail (He) : Lallement’s B + : B in this model (bi-directional) White lines show contour map of the distance to LIC boundary by Redfield & Linsky (2000).

Large-scale distribution of proton intensity (not -ray) Comparison with UG- observations Two-hemisphere UG- observations @~0.5 TeV (Hall et al., JGR, 103, 1998 &104, 1999) (5°x5° pixels) (15°x15° pixels) Large-scale distribution of proton intensity (not -ray) Deep UG- observations by Super Kamiokande @~10 TeV Guillian et al., PRD, in press (2007)

Energy dependence No significant E-dependence up to ~100 TeV 4 TeV 6 “Normalized” intensity Significance 4 TeV 6 No significant E-dependence up to ~100 TeV 12 50 100

Local sidereal time (hour) 銀河異方性と恒星時日周変動 d=90o d=30.1o 長期安定稼動 大気効果の補正 （等天頂角法、E-W法） 系統誤差  0.01%を実現 0 6 12 18 24 Local sidereal time (hour) 恒星時日周変動 赤緯依存性を観測できない。 （自転軸に平行な流れは検出不可）

Energy responses to 1-ry CRs AS（Tibet III）

E-spectra of SDV amplitude （Before Tibet III） Nagashima, Fuｊimoto & Jacklyn (1998) Loss-cone Tail-In Both TI & LC @~300GeV No significant TI @10TeV TI has a soft E-spectrum J/J~γE/E with const. E ⇒ accl. in heliotail? Tail-In Loss-cone

Tibet III results (AS@10TeV) Amenomori et al. (ApJL, 626, 2005) Tibet III all-dec. is consistent with Nor. TI seen in the south TI phase shifts earlier in south (amp. larger)

Lallement et al. (2004) Tibet AS 28±15° 27° Gurnett et al. (2006)

gal. North gal. East gal. East gal. center

Positive (qA>0) Negative (qA<0) 0.5 TV 1 TV 10 TV (meridian) (equatorial) (meridian) (equatorial) 0.5 TV 1 TV 10 TV