Tibet Air Shower Array Results and Future Plan

Tibet Air Shower Array Results and Future Plan - Gamma Ray Observation - K. Kawata For the Tibet ASg Collaboration ICRR, University of Tokyo International Conference on Topics in Astroparticle and Underground Physics (TAUP) 2007 Sendai, Japan, September 11 -15, 2007 1

Contents p Tibet Air Shower Array p Recent Results Crab Nebula l MGRO J 2019+37 (Cygnus Region) l MGRO J 1908+06 l p Future Plan (Tibet muon detector project) Simulation l Sensitivity l Expected Results l Prototype MD l p Summary 2

The Tibet ASg Collaboration M. Amenomori 1, X. J. Bi 2, D. Chen 3, S. W. Cui 4, Danzengluobu 5, L. K. Ding 2, X. H. Ding 5, C. Fan 6, C. F. Feng 6, Zhaoyang Feng 2, Z. Y. Feng 7, X. Y. Gao 8, Q. X. Geng 8, H. W. Guo 5, H. H. He 2, M. He 6, K. Hibino 9, N. Hotta 10, Haibing Hu 5, H. B. Hu 2, J. Huang 11, Q. Huang 7, H. Y. Jia 7, F. Kajino 12, K. Kasahara 13, Y. Katayose 3, C. Kato 14, K. Kawata 11, Labaciren 5, G. M. Le 15, A. F. Li 6, J. Y. Li 6, Y. -Q. Lou 16, H. Lu 2, S. L. Lu 2, X. R. Meng 5, K. Mizutani 13, 17, J. Mu 8, K. Munakata 14, A. Nagai 18, H. Nanjo 1, M. Nishizawa 19, M. Ohnishi 11, I. Ohta 20, H. Onuma 17, T. Ouchi 9, S. Ozawa 11, J. R. Ren 2, T. Saito 21, T. Y. Saito 22, M. Sakata 12, T. K. Sako 11, M. Shibata 3, A. Shiomi 9, 11, T. Shirai 9, H. Sugimoto 23, M. Takita 11, Y. H. Tan 2, N. Tateyama 9, S. Torii 13, H. Tsuchiya 24, S. Udo 11, B. Wang 8, H. Wang 2, X. Wang 11, Y. Wang 2, Y. G. Wang 6, H. R. Wu 2, L. Xue 6, Y. Yamamoto 12, C. T. Yan 11, X. C. Yang 8, S. Yasue 25, Z. H. Ye 15, G. C. Yu 7, A. F. Yuan 5, T. Yuda 9, H. M. Zhang 2, J. L. Zhang 2, N. J. Zhang 6, X. Y. Zhang 6, Y. Zhang 2, Yi Zhang 2, Zhaxisangzhu 5 and X. X. Zhou 7 (1) Department of Physics, Hirosaki University, Hirosaki 036 -8561, Japan. (2) Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China. (3) Faculty of Engineering, Yokohama National University, Yokohama 240 -8501, Japan. (4) Department of Physics, Hebei Normal University, Shijiazhuang 050016, China. (5) Department of Mathematics and Physics, Tibet University, Lhasa 850000, China. (6) Department of Physics, Shandong University, Jinan 250100, China. (7) Institute of Modern Physics, South. West Jiaotong University, Chengdu 610031, China. (8) Department of Physics, Yunnan University, Kunming 650091, China. (9) Faculty of Engineering, Kanagawa University, Yokohama 221 -8686, Japan. (10) Faculty of Education, Utsunomiya University, Utsunomiya 321 -8505, Japan. (11) Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277 -8582, Japan. (12) Department of Physics, Konan University, Kobe 658 -8501, Japan. (13) Research Institute for Science and Engineering, Waseda University, Tokyo 1698555, Japan. (14) Department of Physics, Shinshu University, Matsumoto 390 -8621, Japan. (15) Center of Space Science and Application Research, Chinese Academy of Sciences, Beijing 100080, China. (16) Physics Department and Tsinghua Center for Astrophysics, Tsinghua University, Beijing 100084, China. (17) Department of Physics, Saitama University, Saitama 338 -8570, Japan. (18) Advanced Media Network Center, Utsunomiya University, Utsunomiya 3218585, Japan. (19) National Institute of Informatics, Tokyo 101 -8430, Japan. (20) Tochigi Study Center, University of the Air, Utsunomiya 321 -0943, Japan. (21) Tokyo Metropolitan College of Industrial Technology, Tokyo 116 -8523, Japan. (22) Max-Planck-Institut für Physik, München D-80805, Deutschland. (23) Shonan Institute of Technology, Fujisawa 251 -8511, Japan. (24) RIKEN, Wako 351 -0198, Japan. (25) School of General Education, Shinshu University, Matsumoto 390 -8621, Japan. 3

Tibet-III Air Shower (AS) Array Tibet Muon Detectors (Future Image) Yangbajing, Tibet, CHINA, 4300 m a. s. l. p Number of Scinti. Det. p Effective Area for AS p Energy region p Angular Resolution (Gamma rays) p Energy Resolution (Gamma rays) p F. O. V. 0. 5 m 2 x 789 ~37, 000 m 2 ~Te. V - 100 Pe. V ~0. 4 @10 Te. V ~0. 2 @100 Te. V ~70% @10 Te. V ~40% @100 Te. V ~2 sr 2 nd particles Timing & Energy deposit 4

Energy Spectrum of Gamma rays from the Crab Nebula Pre 30 th ICRC 2007, Merida, Mexico ary n i il m Consistent with other observations using IACT Centered at Crab position 5

Moon Shadow Verification p Absolute energy scale p Angular resolution p Pointing error Constant fitting -0. 0034 o + 0. 011 o Energy dependence of Displacements Caused by Geomagnetic field Systematic pointing error < 0. 01 o Absolute Energy Scale error – 4. 4% +- 7. 9%stat +- 8%sys 6

Northern Sky Survey & Cygnus Region 30 th ICRC 2007, Merida, Mexico vsmooth radius 1. 5° ry a n i m i el Pr lt u s re Red --without Crab and Mrk 421 and Cygnus region MGRO J 2019+37 Tibet: 5. 8 s 7

MGRO J 2019+37 Energy Spectrum m li e r P Milagro 1 0 0 % g a m m a - r a ys a s s u m e d ry a in Tibet AS has no ability for Gamma/Hadron separation Assuming 100% of the excess is caused by gamma rays Not inconsistent with Milagro flux ØMilagro flux is E 2 d. N/d. E=(3. 49± 0. 47 stat ± 1. 05 sys)x 10 -12 Te. Vcm-2 s-1 from 3 x 3 square degree bin centered on the location of Hotspot (304. 83 o, 36. 83 o) at 12 Te. V, assuming a differential source spectrum of E-2. 6(reference : Ap. J 658: 2007). 30 th ICRC 2007, Merida, Mexico 8

MGRO J 1908+06 Milagro error circle G 40. 5 -0. 5 (stat. +sys. ) MGRO J 1908+06 Ge. V J 1907+0557 G 39. 2 -0. 3 Tibet error circle Tibet AS: In 2003, marginal excess ~4. 4σ (pre-trial) Subsequently Milagro: clear excess (MGRO J 1908+06) J. L. Zhang for the Tibet ASγ Collaboration, 28 th ICRC, vol. 4, pp 2405 - 2408 (2003) Amenomori et al. , 29 th ICRC, vol. 4, pp 93 - 96 (2005) Amenomori et. al, Ap. J 633, 1005 (2005) 9

Tibet Muon Detector (MD) Array 7. 2 m x 1. 5 m depth　Water pool 20”FPMT x 2　 (HAMAMATSU R 3600) Underground 2. 5 m ( ~515 g/cm 2~19 X 0) Material: p Concrete pool p White paint 　　　　192 detctors 　　　　Total　~10, 000 m 2 　　　　 MD ~10, 000 m 2 extends AS to ~83, 000 m 2 Counting the number of muons accompanying an air shower Gamma/Hadron separation 10

Muon Number vs. Shower Size (Simulation) Sr: Sum of particle density by all scintillation det. Shower Size SNPE: Sum of photoelectrons by all muon det. Muon number 　　　 SNPE ( µ Muon Number) (gamma) 10 Te. V 1000 Te. V (~10 Te. V) Gamma CR 99. 8% Rejection 0 80% 50% 20% (~100 Te. V) Gamma Sr ( Shower Size) 0 CR 11

Sensitivity to Point-like Gamma-ray Source Tibet AS Array 83, 000 m 2 + Tibet MD Array 10, 000 m 2 Crab orbit Search window size 0. 3 degrees >50 Te. V, while angular resolution <0. 3 degrees. F. O. V. ~2 sr 12

Physics Motivation Above 10 Te. V cosmic/gamma ray wide sky survey p Measurement of cut-off energy in gamma ray spectrum Search for Pevatron Cosmic ray origin & acceleration mechanism p Diffuse gamma rays from Galactic plane (including Cygnus) Cosmic ray propagation p Monitoring time variable sources (AGN, GRB…) Measure column density of IR photons p Extragalactic background radiation UHCR cascading p Cosmic ray chemical composition around the Knee region Separate chemical composition by the number of muons 13

Gamma rays in the 100 Te. V region Te. V J 2032+4130 (~5% Crab) Hard spectral index at Te. V energies Faint in other wavelengths p 0 decay Inverse Compton Protons E<1000 Te. V 10 -1000 Te. V Aharonian et al, A&A, 431, 197 (2005) 14

　 Te. V J 2032+4130 Unidentified source Cyg X-3 in Cyg OB 2 HEGRA obs. ~158 hours Extended ~6. 2′ p 0 decay? Crab -2. 62 VERITAS 10000 Te. V Tibet AS+MD p 0 decay model Aharonian et al. A&A, 464, 235(2007) Kelner et al. , PRD 74, 034018 (2006) 　 1000 Te. V 1 year, 5σ Epmax=100 Te. V Aharonian et al, A&A, 431, 197 (2005) 15

　MGRO J 2019+37 　Cygnus diffuse gamma rays o o　 Integral flux in 3 × 3 region Abdo et al. astro-ph/0611691 (2006) Beacom et al. astro-ph/070175 (2007) 16

　Diffuse Gamma Rays from Galactic Plane Electron model p 0 model 10° 0° 180° 120° EGRET data 60° 0° 300° 240° -10° 180° 17

Known Gamma-Ray Sources in the Northern Sky VERITAS Tibet AS+MD 1 year Large Zenith ~ 37 o Large Zenith ~ 39 o HESS J 1837 -069 HESS J 1834 -087 Periodic object MAGIC - Peak flux Cas A LS I +01 303 Mrk 421 Mrk 501 M 87 18

Prototype MD 52 m 2 x 2 units Construction start 1 st September 2007 complete end of November 2007 Feasibility study of construction l Compare with simulation l Search for 1000 Te. V Gamma rays l 19

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Summary l Performance of Tibet Air Shower Array: Angular Resolution 0. 2 o @100 Te. V Energy Resolution ~40% @100 Te. V Systematic Pointing Error < 0. 01 o Absolute Energy Error ~10% Verification by the Moon Shadow l l l Crab Nebula: Energy spectrum observed by Tibet AS is consistent with other observations using IACTs. MGRO J 2019+37: Tibet flux is not inconsistent with Milagro results, if we assume 100% of the excess is caused by gamma rays. MGRO J 1908+06: Marginal excess was found. Tibet AS+MD: 10000 m 2 Water Cherenkov Muon Detector (~5 M US$) Sensitivity is 5 -15% Crab @ 10 -100 Te. V. l 21 l Construction of test MD (52 m 2 x 2) started 1 st September 2007.

Thank you! 22