Two-dimensional observation on TeV Cosmic-ray anisotropy using the Tibet Air Shower Array
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Transcript of Two-dimensional observation on TeV Cosmic-ray anisotropy using the Tibet Air Shower Array
Two-dimensional observation on TeV Cosmic-ray anisotropy
using the Tibet Air Shower Array
2008.9 TeVP
Zhang Yi
For the Tibet AS collaboration
OUTLINE
• The Tibet Air shower Array;• Analysis method;• Sidereal time cosmic rays anisotropy;• Solar time cosmic rays anisotropy; • Periodicity search;• Conclusion ;
中尼公路
Geothermal power plant
The Tibet Air shower Array
– Located at an elevation of 4300 m (Yangbajing , China)– Atmospheric depth 606g/cm2
– Wide field of view – High duty cycle (>90%)– Angular resolution (~0.9 。 )– Data (1997~2005, 37*109)
Advantage in measurement of Cosmic rayLarge scale anisotropy
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
——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
The CR anisotropy is fairly stable and insensitiveto solar activities.
Three Componets :I--------Tail-in;II-------Loss-coneIII------Cygnus 区;
Tibet measurement in two dimensions
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 50TeVrule out the solar causation
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)
3. Solar time anisotropy —— Compton-Getting effect
Differential E spectrum :
The amplitude is ~0.04%
——Compton-Getting effect ( 12TeV )
The solar time anisotropy is table in two intervals with different solar activity
The 1D modulation (solid line) is consitent with the expected one (dash line) 。
Tibet measurement in solar time I
–Kota et al. (icrc0229) Matsushiro
With the compton-getting effect subtracted.The amplitude ~ 0.04% , Preliminary result
——Additional effect (4TeV)
Tibet measurement in solar time II
Preliminary
3. Periodicity search in 3 energy ranges
Solar diurnal.Compton-Getting effect Sidereal-diurnal
Sidereal semi-diurnal
Conclusion•In the sidereal time frame, revealing finer details of the anisotropies components “tail-in” and “loss-cone” and “Cygnus” region direction.
•In the solar time frame, Compton-Getting effect is observed in 12.5TeV, An additional modulation appears to exist in case of low energy.
•Besides solar, sidereal, semi-sidereal diurnal Variation, no other periodic modulation observed.
365.2422364.2422T Solar day
365.2422367.2422T= Solar day
——Observation in other periods
Anti sidereal time ;
Ext-sidereal time ;
No signal is expected, the amplitude observed is within statistic error.
Two-dimension Analysis check II
Nagashima, Fujimoto, Jacklyn (JGR, 103, 1998) Hall et al. (JGR, 103, 1998)
地方恒星时的宇宙线强度变化
Tail-In
Loss-Cone
Tail-In max. shifts earlier in the south
1) 一些地下 μ实验一维观测
Galactic Magnetic field 3uG
Galactic cosmic rays lost their directional information, and are nearly isotropic because of the influence of magnetic fields in the Milky Way.
Galactic Magnetic field
Cygnus
Gyromagnetic radius
3TeV 0.001pc (200AU)
Expected
Expected Amp= 0.0016
The statistic error 0.00026 , 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.
3)Corotaion of the low energy particles
Know anisotropy —— Compton-Getting effect III
The cosmic ray particles would co-rotate with the interplanetary magnetic field (IMF).
Know anisotropy —— Compton-Getting effect I
Δ I< I >
= ( + 2 ) v c cos
A.H. Compton and I.A. Getting, Phys. Rev. 47, 817(1935)L.J. Gleeson and W.I. Axford, Ap. Space Sci. 2, 431(1968)
1) The solar motion around the Galactic center j
8
E-Differential E spectrum :
V=220km/s,