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TeV Cosmic-ray Anisotropy &
Tibet Yangbajing Observatory
Qu XiaoboInstitute of High Energy Physics
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ARGO HallTibet AS array
Yangbajing Observatory
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The Tibet Air shower Array– Located at an elevation of 4300 m (Yangbajing , China)– Atmospheric depth 606g/cm2
– Wide field of view (Dec. -15º,75º )– High duty cycle (>90%)– Angular resolution (~0.90)
Advantage----measurement of Cosmic rayLarge scale anisotropy
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OUTLINE
• Large scale anisotropy in sidereal time
• Energy dependence • Time evolution• Models
• Compton-Getting effect• Solar time anisotropy• Periodicity• Summary
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Energy dependence Sidereal time anisotropy
Amenomori, APJ, 2005
Harmonic analysis
“East-west”(E-W) subtraction method
increase
independent
decrease
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A. D. Erlykin, A. W. Wolfendale, Astropart. Phys. 25, 183(2006)
Anisotropy expected by CR production and propagation
(R – rigidity)(δ ~ 0.3-0.6 )
Important probe, discover CR origin, study CR propagation.
Diffusion model: The amplitude of anisotropy
increase with the energy!
1. Random character of SN explosions;
2. Mixed primary mass composition;
3. Possible e ect of the single source;ff
4. The Galactic Halo;
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Sidereal time anisotropy
Tail-In max. shifts earlier in the south
Tail-In
Loss-Cone
Tail-In
Loss-Cone
Hall et al. (JGR, 104, 1999)
Hall et al. (JGR, 103, 1998)
Structure analysis NFJ model
Tail-in
Loss-cone
Gaussian analysis
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Zenith
On-source
Off-sourceOff-source
,on onI N N
Ion
on
N
Ioff
off
——Global fitting method
2on on
2
2
2
1on on off,i off,in
N I -<N/I> i2on 2 21
on on off,i off,ini
N I - N I
χ =N I + N I
2 2,
,t on
t on
Equal
,off offI N
Two dimension analysis method
Zenith belt
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The CR anisotropy is fairly stable in two samples.
Three Componets :I--------Tail-in;II-------Loss-coneIII------Cygnus region ;
Tibet measurement in two dimensions
<<Anisotropy and Corotation of Galactic Cosmic Rays >> M. Amenomori et al., Science, 314 429 (2006)
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Large scale anisotropy in two dimension
Milagro
Super-Kamiokande-I
Also by ARGO, Icecube
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4 TeV
6.2 TeV
12 TeV
50 TeV
300 TeV
Celestial Cosmic Ray intensity map in five energy range
<12TeV Energy independent >12TeV Fade away
“Tail-in” effect exists in 50TeV, rule out the solar causation.
Energy dependence
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Sidereal time anisotropy by ARGO
1.5TeV
0.7TeV
3.9TeV
Median energy
<<Observation of TeV cosmic ray anisotropy by the ARGO-YBJ experiment>> ICRC0814,2009
Energy dependence
Consistent with the 1D observations, finer structure in 2D
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Sidereal time anisotropy in 9 Phases (1999-2008)
<<On Temporal Variations of the Multi-TeV Cosmic Ray Anisotropy Using the Tibet III Air Shower Array >>, M. Amenomori et al., ApJ 711, 119 (2010)
Temporal Variations
Stable Insensitive to solar activitiesImproved analysis method, more statistic.
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Temporal Variations
Time Evolution of the Sidereal Anisotropy
The fundamental harmonicincrease in amplitude with time.
Milagro observation
No steady increase
Matsushiro Observation
Tibet Observation
1999-2008
2000-2007
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Sidereal time anisotropy in two hemisphere
Tibet IIIIcecube
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Sidereal time anisotropy in Galactic coordinate
Tibet III
Icecube
Cosmic ray flows in three directions
Inward flowsOutward flowsElectrically neutral state
Excess
X.B.Qu et al., arXiv:1101.5273
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Magnetic field induced by Cosmic ray flows
Extend the anisotropy imageobserved in the solar vicinity to the whole Galaxy.
30
4 r
rlIdBd
Biot-Savart Law
A0 dynamo model J.L. Han,19971. Magnetic Field Structure, Consistent 2. The extension of the local anisotropy to the whole Galaxy is reasonable.
X.B.Qu et al., arXiv:1101.5273
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Alternative Model of the Sidereal time anisotropy
Amenomori, M., et al. 2010, Astrophys. Space Sci. Trans., 6, 49
Global +Midscale Anisotropy
Two intensity enhancements along a
Hydrogen Deflection Plane
Hydrogen Deflection Plane
uni-directional flow +bi-directional flowLocal interstellar magnetic field
Residual anisotropy after subtracting In,m
In,mIn,m(GA)
In,m(MA)
Residual anisotropy after subtracting In,m(GA)
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LIMC (Local Interstellar Magnetic Cloud) modelLocal Interstellar Cloud, egg-shaped cloud, 93 pc3. Cosmic ray density (n) lower inside LIC than outside, adiabatic expansion
⊥Perpendicular∥Parallel
uni-directional flow (UDF) ⊥bi-directional flow (BDF) ∥
LISMF
Alternative Model of the Sidereal time anisotropy
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Known origin of large scale anisotropy
—— Compton-Getting Effect
Δ I< I >
= ( + 2 ) v c cos
A.H. Compton and I.A. Getting, Phys. Rev. 47, 817(1935)
Due to the solar motion around galactic center j E-
8
V=220km/s,
Expected dipole effect
We could observe
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Expected
Expected Amp= 0. 16%
The statistic error 0. 026% , ~5σ rule out the Compton-Getting effect.
Celestial Cosmic Ray intensity map for 300 TeV
These results have an implication that cosmic rays in this energy range is still strongly deflected and randomized by the Galactic magnetic field in the local environment.
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Δ I< I >
= ( + 2 ) v c cos
Due to terrestrial orbital motion around the Sun
j
8
E-
V=30km/s,
D.J. Cutler, D.E. Groom, Nature 322, L434 (1986)
Known origin of large scale anisotropy
—— Compton-Getting effect
Differential E spectrum :
The amplitude is ~0.04%
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——Compton-Getting effect ( 12TeV )
The solar time anisotropy is stable in two intervals with different solar activity
The 1D modulation (solid line) is consistent with the expected one (dash line) 。
Tibet measurement in solar time I
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With the compton-getting effect subtracted.The amplitude ~ 0.04%.
——Additional effect (4TeV)
Tibet measurement in solar time II
Preliminary
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Periodicity search in 3 energy ranges
Solar diurnal.Compton-Getting effect Sidereal-diurnal
Sidereal semi-diurnal
<<Observation of Periodic Variation of Cosmic Ray intensity with the Tibet III Air Shower Array>>, A.-F. Li Nuclear Physics B,, 529, 2008.
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Summary•Yangbajing Observatory successfully observed the Cosmic ray anisotropy.(0.7TeV-300TeV)
•Energy dependence, time evolution, Periodicity analysis of the anisotropy
•In the sidereal time frame, revealing finer details of the anisotropies components “tail-in” and “loss-cone” and “Cygnus” region direction. Models given. origin???
•In the solar time frame, Compton-Getting effect is observed in 12TeV, An additional modulation appears to exist in case of low energy.
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中意 ARGO 实验大厅
中日 AS 探测阵列
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365.2422364.2422T Solar day
365.2422367.2422T= Solar day
Anisotropy Observations in other periods
Anti sidereal time
Ext-sidereal time
No signal is expected, the amplitude observed is within statistic error.
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银河系磁场强度为 3uG 时
带电粒子在传播过程中受磁场影响而偏离其原本方向.星际磁场就像一个搅拌机,将宇宙线粒子搅拌得各向同性.
银河宇宙线在磁场中传播
Cygnus 方向
回旋半径
3TeV 对应 0.001pc (200AU)
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——NFJ model
zoh_N
zoh_V
zoh_S
-0.1
0
0.1
lia_2N
zoh_2S
lia_N
lia_V
0 6 12 18 24 30 36 42 48
lia_S
57.0N
34.5N
11.2N
8.2S
4.4N
36.2S
14.7S
57.6S
zoh_N
zoh_V
zoh_S
-0.1
0
0.1
lia_2N
zoh_2S
lia_N
lia_V
0 6 12 18 24 30 36 42 48
lia_S
57.0N
34.5N
11.2N
8.2S
4.4N
36.2S
14.7S
57.6S
Sidereal time anisotropy components
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Nagashima, Fujimoto, Jacklyn (JGR, 103, 1998) Hall et al. (JGR, 103, 1998)
Tail-In
Loss-Cone
Tail-In max. shifts earlier in the south
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One-dimensional observation Sidereal time anisotropy
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太阳时各向异性低能处比较明显,随刚度幂律分布
存在截止刚度 ,经测量
,2.01.0 GVPu 25100
随太阳 活动有 11 年的周期变化,活动极小时,低至几 GV ,极大时,可达 200GV
最近观测发现, 600GV 宇宙线太阳时各向异性仍受到太阳活动的调制; Tibet ASγ 在 4TeV 处观测到超出 CG 效应的太阳时各向异性,高能处与预期 CG 效应一致
宇宙线及大尺度各向异性
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Medium scale anisotropy
Milagro
ARGO
Tibet-III
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Large scale anisotropyMilagro
Tibet-III