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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. Hu
ang, 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
6th IGPP meeting in Hawaii: March 21, 2007
• 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 -rays, while the muon detector respond only to 1ry protons.
Cosmic ray observation with AS array
Neutron monitor
Muon detector
Air shower array
1ry
Tibet ASγ experiment
Tibet@ChinaTibet@China
Yangbajing 90 ゜ 53E, 30 ゜ 11N 4,300 m a.s.l.
Lasa
Yangbajing~300 km
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 resolutionin multi-TeV region
Sidereal anisotropy on the spinning Earth
● The zenith direction at Yanbajing is =30.1o.
● Fixed direction in the horizontal coordinate travels along =const. for 360o of right ascension once every one sidereal day.
With the spin of Earth, the zenith direction travels along =30.1o .●
● AS flux varies for more than an order of magnitude with the zenith angle due to the different atmospheric depth.
=30.1o =30.1o
=90o
The average flux in each -band is subtracted.
Geographical equator
Galactic plane
right ascension (º)
dec
linat
ion
(º)
Nose direction
“Normalized” intensity map (5°x5° pixels)
Significance map
~120°
90° < 120° < 180°
Bi-directional + Uni-directional
2D sky map of CR intensity by Tibet AS(Amenomori et al., Science, 314, 2006)
•RL~ 0.01pc (for 10TeV p in 1G)
•Dist. to LIC boundary ~26km/s3000y
=0.08pc•Probably within 1 m.f.p. in the weakscattering regime
LIC (Local Interstellar Cloud)T~7000K, nH~0.1/ccIonization rate~0.52
Redfield & Linsky, ApJ, 535, 2000
2 pc
GC
l=90
l=180
l=27
0
Lallement’s Interstellar B plane(Lallement et al., Science, 307, 2005)
lB= 205~240 bB= -38~-60
(or the opposite direction)
H
He
Interstellar B
n
Uni-directional flow(Bxn)
Bi-directional flow
n Low
n HighLIC
G cloud
LIMC (Local Interstellar Magnetic Cloud) model
If cosmic ray density (n) is lower inside LIC than outside….
26 km/s
29 km/s
Best-fitting (preliminary)(I/I)cal = a1cos1() : Uni-directional
+ a2+cos2 2() for 0 2/2 + a2-cos2 2(2, 2) for /2 2
1, 2 : angles from reference axes
First choose orientations of reference axes… & (or ): () ()
then a1, a2+ & a2- are given by linear LSM.
d.o.f. with 6 free parameters is large as…90x360/(5x5)-6=1,290
: Bi-directional
Result: Uni-directional Bi-directional
a1=0.0016, a2+=0.0018, a2-=0.0010
27.547.5, 97.417.
5
Best-fit intensity distribution
Uni-direct.
Bi-direct
.
Sum
+
=
Original intensity“Normalized” intensity
(average over dec.-band is subtracted)
Mrk421
CrabCygnus region
Best-fit performance
• 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.
observation
model
residual(obs.-model)/error
Comparison with UG-in two-hemispheres
Tibet AS experiment cannot observe southern hemisphere.
: Lallement’s B: LIMC model (Tibet AS)
Best-fit B direction may be different when unbiased, by properly taking account of the data in southern hemisphere.
UG- @0.5 TeVHall et al., JGR, 103, 1998 &104, 1999)
-0.15
0
0.15
-0.3
0
0.3
0 90 180 270 360
UG
(%
) Tib
et (%
)
R.A. (deg)
-0.15
0
0.15
UG
(%
)
-0.15
0
0.15
-0.3
0
0.3
0 90 180 270 360
UG
(%
) Tib
et (%
)
R.A. (deg)
UG- in Japan V (35°N)
Tibet AS
Tibet AS
UG- in Tasmania N (4°N)
UG- in Tasmania V (36°S)
Summary• 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).
: heliotail (He)
: Lallement’s B
+ : B in this model(bi-directional)
Original intensity map (in galactic coordinate)
+
-
++
-0.0016
+0.0016
+0.0018
+0.0010
l (°)
b (
°)
White lines show contour map of the distance to LIC boundary by Redfield & Linsky (2000).
Comparison with UG- observations
Guillian et al., PRD, in press (2007)
Two-hemisphere UG- observations @~0.5 TeV(Hall et al., JGR, 103, 1998 &104, 1999)
Deep UG- observations by Super Kamiokande @~10 TeVLarge-scale distribution of proton intensity
(not -ray)
(5°x5° pixels)
(15°x15° pixels)
4 TeV
6
12
50
100
No significant E-dependence up to ~100 TeV
“Normalized” intensity Significance
Energy dependence
銀河異方性と恒星時日周変動
=90o=90o
=30.1o =30.1o
0 6 12 18 24Local 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)
•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
Energy responses to 1-ry CRs
AS( Tibet III)μ-on
0.01
0.1
1
10
100
1000
0.01 0.1 1 10 100
Nagoya-VMisato-VSakashita-VMatsushiro-V
arb
itra
ry u
nit
primary E (TeV)
-0.2
0
0.2
0 6 12 18 24
Nor.3F(73-87)-0.05Nor.3R(73-87) @10TeVSakV1_corSI(78-94)*4 @300GeV
(%)
hours
Tail-In
Loss-cone
• Both TI & LC @~300GeV• No significant TI @10TeV• TI has a soft E-spectrum
J/J~γE/E with const. E⇒ accl. in heliotail?
E-spectra of SDV amplitude( Before Tibet III)
Nagashima, Fu j imoto & Jacklyn (1998)
Loss-cone
Tail-In
• Tibet III all-dec. is consistent with Nor.• TI seen in the south• TI phase shifts earlier in south (amp. larger)
-0.2
0
0.2 TibetIII(99-03)Nor.3R(73-87)Nor.3F(73-87)
0 6 12 18 24
(%)
hours
Tibet III results (AS@10TeV)
Amenomori et al. (ApJL, 626, 2005)
0 6 12 18 24
si_daily15R:-15+00R:+00+05R:+10+15R:+20+25
R:+30+35R:+40+45R:+50+55
hours
Gurnett et al. (2006) Lallement et al.(2004)
Tibet AS
28±15°27°
gal. North
gal. East
gal. East
gal. center
Positive (qA>0)(meridian) (equatorial)
0.5 TV
10 TV
1 TV
Negative (qA<0)(meridian) (equatorial)