Results of the Telescope Array experiment
Grigory I. Rubtsov
Institute for Nuclear Research of the RAS
ULB Physique Th´eorique seminar
Outline
I
Telescope Array experiment
I
TA physics results on UHECRs
I spectrum
I chemical composition
I search for sources
I search for photons
Telescope Array Collaboration
T Abu-Zayyad1, R Aida2, M Allen1, R Azuma3, E Barcikowski1, JW Belz1, T Benno4, DR Bergman1,
SA Blake1, O Brusova1, R Cady1, BG Cheon6, J Chiba7, M Chikawa4, EJ Cho6, LS Cho8, WR Cho8, F Cohen9,
K Doura4, C Ebeling1, H Fujii10, T Fujii11, T Fukuda3, M Fukushima9,22, D Gorbunov12, W Hanlon1,
K Hayashi3, Y Hayashi11, N Hayashida9, K Hibino13, K Hiyama9, K Honda2, G Hughes5, T Iguchi3,
D Ikeda9, K Ikuta2, SJJ Innemee5, N Inoue14, T Ishii2, R Ishimori3, D Ivanov5, S Iwamoto2, CCH Jui1,
K Kadota15, F Kakimoto3, O Kalashev12, T Kanbe2, H Kang16, K Kasahara17, H Kawai18, S Kawakami11,
S Kawana14, E Kido9, BG Kim19, HB Kim6, JH Kim6, JH Kim20, A Kitsugi9, K Kobayashi7, H Koers21,
Y Kondo9, V Kuzmin12, YJ Kwon8, JH Lim16, SI Lim19, S Machida3, K Martens22, J Martineau1, T Matsuda10,
T Matsuyama11, JN Matthews1, M Minamino11, K Miyata7, H Miyauchi11, Y Murano3, T Nakamura23,
SW Nam19, T Nonaka9, S Ogio11, M Ohnishi9, H Ohoka9, T Okuda11, A Oshima11, S Ozawa17, IH Park19,
D Rodriguez1, SY Roh20, G Rubtsov12, D Ryu20, H Sagawa9, N Sakurai9, LM Scott5, PD Shah1, T Shibata9,
H Shimodaira9, BK Shin6, JD Smith1, P Sokolsky1, TJ Sonley1, RW Springer1, BT Stokes5, SR Stratton5,
S Suzuki10, Y Takahashi9, M Takeda9, A Taketa9, M Takita9, Y Tameda3, H Tanaka11, K Tanaka24,
M Tanaka10, JR Thomas1, SB Thomas1, GB Thomson1, P Tinyakov12,21, I Tkachev12, H Tokuno9, T Tomida2,
R Torii9, S Troitsky12, Y Tsunesada3, Y Tsuyuguchi2, Y Uchihori25, S Udo13, H Ukai2, B Van Klaveren1,
Y Wada14, M Wood1, T Yamakawa9, Y Yamakawa9, H Yamaoka10, J Yang19, S Yoshida18, H Yoshii26, Z Zundel1
1University of Utah, 2University of Yamanashi, 3Tokyo Institute of Technology, 4Kinki University,
5Rutgers University, 6Hanyang University, 7Tokyo University of Science, 8Yonsei University,
9Institute for Cosmic Ray Research, University of Tokyo, 10Institute of Particle and Nuclear Studies, KEK,
11Osaka City University, 12Institute for Nuclear Research of the Russian Academy of Sciences,
13Kanagawa University, 14Saitama University, 15Tokyo City University, 16Pusan National University,
17Waseda University, 18Chiba University 19Ewha Womans University, 20Chungnam National University,
21University Libre de Bruxelles, 22University of Tokyo, 23Kochi University, 24Hiroshima City University,
Telescope Array observatory
I 507 SD’s, S = 3m2
I 3 FD’s
TA surface detector
solarpanel (120w) wLAN (2.4GHz) electronics box (100Ah) battery + box scintillator GPS < Surface Detector > • 3m2 (12mm × 2 layers) • PMTs: ET 9123SA × 2 (2cm separation) • WLSF: 1.0mmφ ∼200kgM. Takeda, JPS meeting, March 2010 < SD Observation Status > 15947.3 hrs 94.2 % 16160.7 hrs 95.7 % 16484.0 hrs 97.5 % MJD Observation Time [hr] Observation Time [hr] Observation Time [hr]
Mar’08 Nov’08 Nov’09Feb’10
Black Rock Mesa
Long Ridge Smelter Knoll 54600 54800 55000 55200 0 10 20 0 10 20 0 10 20 • operation in stable ∼ > 95% ∼ > 16k hours • wLAN interference in early stage • thunder storms in summer • maintenance access in autumn
• low temperature & snow in winter
SD event example
M. Takeda, JPS meeting, March 2010
< SD Event Example > 2.0 0.2 1.7 22.9 74.6 2.2 1.5 26.3 117.8 2.2 2.4 3.6 1.9 0.3 0.8 0.5 RUN(50141) EVENT(2182) DATE(080531) TIME(050737) Log(E[eV])=19.698η = 3.542 Zenith=36.246[deg] Azimuth= 27.854[deg] Core(9) ChiD(0.09) ChiCS(1.39)
1318 X [m] Y [m] 1401 1404 1608 1611 1612 1613 1707 1710 1711 1712 1713 1803 1805 1810 1811 0 5000 10000 −10000 −5000 0 0 10000 20000 30000 1 10 102 103 104 Core Distance [m] Td [nsec] 108 106 104 102 100 Density [m ] −2 1812 1813 1911 1912 1913 1914 2012 2014 2213 2313
Relative Timimg [nsec]
102 103 104 105 106 107 108 109 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 #FADC (raw) 102 103 104 100 10 10 10 4 2 6 Core Distance [m]
< FD Observation Status > Nov’07 Feb’10 May’09 2506.2 hrs 12.4 % 2180.4 hrs 10.8 % Observation Time [hr] MJD
Observation Time [hr] Long Ridge
Black Rock Mesa
0 5 10 54400 54600 54800 55000 55200 0 5 10
• Full operation since Nov ’07
• Long Ridge remote operation since May ’09
• ∼> 2.5k hrs
• ∼> 2.1k hrs
FD event example
M. Takeda, JPS meeting, March 2010
< Atmospheric Monitor (LIDAR, CLF) & LINAC > LINAC CLF 100m 20.85km LIDAR 109e (6.4mJ) 40MeV @355nm @355nm 4mJ 5mJ 【back-scat.】 【side-scat.】 【electron shower】
TA-LINAC: Linear Accelerator @ TA
I Electron accelerator 100 m from TA FD I Rate 0.5 Hz I Energy∼ 40 MeV I Current 10− 250pC/pulseT.Shibata, UHECR-2010, Nagoya Fist run: September 2010
Telescope Array physics objectives
Study of UHECR E& 1018 eV
I Spectrum
I Chemical composition
I Search for sources
I Search for photons and neutrino
I Hadronic interactions properties
TA physics results
I I. UHECR spectrum
I II. Chemical composition by XMAX stereo
I III. Search for cosmic ray sources
GZK effect
Greisen, 1966; Zatsepin, Kuzmin, 1966
Cut-off predicted for E& 1019.7eV. p + γ2.7K→ n + π+
→ p + π0
AGASA spectrum, 2003
Takeda, M. et al., Astropart. Phys 19(2003)
I Expected 1.9 event I Observed 11 events
Cut-off observation by HiRES
Monocular: Quarks’06; PRL 100 (2008) Stereo: Astropart. Phys. 32 (2010)
Pierre Auger spectrum
Telescope Array spectrum
TA measures spectrum by three techniques:
I Middle Drum fluorescence detector (FD) mono
I Surface detector (SD)
Monocular spectrum from Middle Drum (MD) detector
I MD uses 14 refurbish HiRes-1 telescopes.
I TAMD mono processing is identical to HiRes-1 monocular data analysis
I same program set
I same “average” atmospheric model
I same event selection, cuts
I Differences:
I telescope location and pointing directions
I Thresholds (∼ 20% lower than HiRes-1)
I Exposure is calculated with Monte-Carlo
Jui, ICRC 2009
10
MD Spectrum
Surface detector spectrum
Dataset:
I Geometrical cuts:
I θ < 45◦
I core inside the array, distance to border > 1200 m
I Cuts on reconstruction quality:
I number of detectors hit >= 4
I χ2/d.o.f < 4.0
I pointing direction resolution < 5◦
I fractional S800 uncertainty < 0.25
I 1.75 years, 6264 events after cuts
Energy scale normalization
I SD energy: CORSIKA QGSJET-II full MC
I FD energy: MD mono, BRM, LR hybrid
I Result: E = ESD/1.27
TA surface detector spectrum
GZK cut-off statistical significance
Surface detector, MD mono and hybrid spectra
Note: SD energy normalized by 27%
Comparison with AGASA, HiRes, Auger
Spectrum summary
I Cut-off is observed by HiRES and confirmed by Pierre Auger and Telescope Array experiments
I GZK process in not questioned, but it’s contribution to cut-off is unknown due to unknown spectrum and composition at the sources
I One may probe E > 1020 eV physics by looking at GZK secondaries: photons and neutrinos
Auger/HiRES XMAX results
Auger Phys.Rev.Lett.104.091101 E [eV] 18 10 19 10 ] 2 > [g/cm max <X 650 700 750 800 850 proton iron QGSJET01 QGSJETII Sibyll2.1 EPOSv1.99 E [eV] 18 10 19 10 ] 2 ) [g/cm max RMS(X 0 10 20 30 40 50 60 70 proton iron HiRES Phys.Rev.Lett.104.161101Yakutsk array result on chemical composition
0.5 1 1.5 2 ΡΜ obs ΡΜ sim, p 0 2 4 6 8 Number of events EPOS p 0.5 1 1.5 ΡΜ obs ΡΜ sim, Fe 0 2 4 6 8 Number of events EPOS Fe 0.29≤ Fe≤ 0.68 (95%CL), E > 1019 eV Glushkov et al, JETP Letters 87:190-194,2008Possible interpretation of Auger result
’The disappointing model’
10 17 10 18 10 19 10 20 10 23 10 24 E m ax =4 EeV g =2.3, d=40 Mpc E 3 J( E ) , e V 2 m -2 se c -1 st e r -1 E, eV Auger 09 r e ct i lin e a r K o lm . d if fu si o n protons 10 17 10 18 10 19 10 20 10 23 10 24 E m ax =4 EeV g =2.3, d=40 Mpc E 3 J( E ) , e V 2 m -2 se c -1 st e r -1 E, eV Auger 09 r e ct i lin e a r K o lm . d if fu si o n nuclei protons
R. Aloisio, V. Berezinsky, A. Gazizov arXiv:0907.5194v1
I No GZK-photons, no GZK-neutrino
Another interpretation of Auger result
R. Engel, 31th ICRC, arXiv:0906.0418v1
0.2 0.3 0.4 1 2 3 4 5 6 ] −2 [gcm max Mean X 720 740 760 780 800 820 840 860 880 900 920 cross section multiplicity elasticity 19 f 0.2 0.3 0.4 1 2 3 4 5 6 ] −2 [gcm max RMS X 30 40 50 60 70 80 90 100 110 Auger, Phys.Rev.Lett.104.091101
Auger/HiRES XMAX results
Auger: I Southern hemisphere I Heavy nuclei or cross-section growth HiRES: I Northern hemisphere I Protons dominate?
Telescope Array stereo result
TA data favorprotons
data collection is in progress
TA XMAX distributions
TA XMAX distributions
Auger claim discussion
I HiRES doesn’t see correlations with AGN (2 of 13, bg: 3) Astropart.Phys.30,2008
I Comment by Gorbunov,Tinyakov,Tkachev,Troitsky
JETP Lett.87,2008
I Events do not follow prediction of AGN hypothesis. E.g.
nothing comes from Virgo, while it contains significant fraction of nearby AGNs
I Cen A may be a single source with correlation angle
about 20◦
I AGN correlation requires proton primaries; contradicts with Auger composition results due to large deflection of nuclei in Galactic magnetic field
Pierre Auger claim discussion: Cen A
20 40 60 80 100
distance from Cen A, deg
-5 -4 -3 -2 -1 0 Log 10 P
The Monte-Carlo probability P to have the observed number of events in a circle of a given radius around Cen A on the celestial sphere, out of the 27 events of the Auger sample. Gorbunov,Tinyakov,Tkachev,Troitsky, arXiv:0804.1088
Auger AGN correlation update
Pierre Auger collaboration, Astropart. Phys. 34 (2010) Before publication date: 9/13 correlate. Background: 2.7± 1.6 After publication date: 12/42 correlate. Background: 8.9± 3.0
Auger Centaurus A update
Pierre Auger collaboration, Astropart. Phys. 34 (2010)
I Cen A may be a source
TA result on AGN correlation
TA result on AGN correlation
correlate: 6 of 15, bg: 3.6
TA Autocorrelation analysis
TA Autocorrelation analysis
TA correlations with LSS
TA correlations with LSS
TA LSS: result of the statistical tests
TA LSS: result of the statistical tests
Sources summary
I Correlations with AGN: 6/15 correlate; compatible with background;
I No significant clustering at E > 10 EeV and E > 40 EeV;
I Data with E > 40 EeV are compatible both with structure and isotropy;
I Data with E > 57 EeV are compatible with structure and incompatible with isotropy at 95% CL;
Photon search techniques
Photon-sensitive parameter:
AGASA, Yakutsk muon density (strongest discrimination)
Pierre Auger SD shower front curvature and thinkness
Pierre Auger hybrid XMAX
Shower front curvature
deep shower maximum = curved front
I We use Linsley’s shower front curvature parameter “a” as a composition sensitive parameter
TA SD photon search
Dataset:
I Data collected by SD from 2008-05-11 to 2009-10-08 I Geometrical exposure for θ∈ [θ1, θ2]:
Ageom= 2346× (sin2θ2− sin2θ1) km2 sr yr
Cuts for photon search:
I Number of detectors triggered is 7 or more
I Shower core distance to array boundary is larger than 1 separation unit (1200 m)
Front curvature example
8.5 8.6 8.7 8.8 8.9 9 9.1 9.2 9.3 9.4 9.5 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 front delay [1200m]; core distance [1200m] Fit data Average photonLinsley curvature “a”: data vs photon MC
0◦− 30◦ h_gm Entries 3758 Mean 0.8287 RMS 0.2954 Underflow 0.1609 Overflow 0.3217 a 0 0.20.40.6 0.8 1 1.21.4 1.61.8 2 0 20 40 60 80 100 120 140 h_gm Entries 3758 Mean 0.8287 RMS 0.2954 Underflow 0.1609 Overflow 0.3217 h_dt Entries 604 Mean 0.5789 RMS 0.2067 Underflow 0 Overflow 0 h_dt Entries 604 Mean 0.5789 RMS 0.2067 Underflow 0 Overflow 0 45◦− 60◦ h_gm Entries 3761 Mean 0.738 RMS 0.2737 Underflow 0 Overflow 1.881 a 0 0.20.40.6 0.8 1 1.21.4 1.61.8 2 0 20 40 60 80 100 120 140 h_gm Entries 3761 Mean 0.738 RMS 0.2737 Underflow 0 Overflow 1.881 h_dt Entries 335 Mean 0.3463 RMS 0.1108 Underflow 0 Overflow 0 h_dt Entries 335 Mean 0.3463 RMS 0.1108 Underflow 0 Overflow 0 30◦− 45◦ h_gm Entries 8804 Mean 0.7766 RMS 0.2726 Underflow 0.1037 Overflow 0.3111 a 0 0.20.40.60.8 1 1.21.41.61.8 2 0 20 40 60 80 100 120 140 h_gm Entries 8804 Mean 0.7766 RMS 0.2726 Underflow 0.1037 Overflow 0.3111 h_dt Entries 456 Mean 0.4881 RMS 0.1685 Underflow 0 Overflow 0 h_dt Entries 456 Mean 0.4881 RMS 0.1685 Underflow 0 Overflow 0 Eγ > 1019 eV data photon MC, E−2 spectrumEvent-by-event method
I For each event with curvature aobs we select photon MC events compatible by arrival direction and S800.
I We calculate curvature distribution function fγ(a) for MC photons I Let’s define C = aobs Z −∞ fγ(a)da I C is defined event-by-event
I For gamma events,C is uniformly distributed between 0 and 1 (independently of the photon primary spectrum).
C: data vs photon MC
0◦− 30◦ h_gm Entries 3758 Mean 0.5024 RMS 0.2819 Underflow 0 Overflow 0.1608 C 0 0.10.20.3 0.40.5 0.60.7 0.80.9 1 0 20 40 60 80 100 120 140 160 180 h_gm Entries 3758 Mean 0.5024 RMS 0.2819 Underflow 0 Overflow 0.1608 h_dt Entries 604 Mean 0.1847 RMS 0.1848 Underflow 0 Overflow 0 h_dt Entries 604 Mean 0.1847 RMS 0.1848 Underflow 0 Overflow 0 45◦− 60◦ h_gm Entries 3761 Mean 0.5051 RMS 0.2843 Underflow 0 Overflow 0.0891 C 0 0.10.20.3 0.40.5 0.60.7 0.80.9 1 0 20 40 60 80 100 120 140 160 180 h_gm Entries 3761 Mean 0.5051 RMS 0.2843 Underflow 0 Overflow 0.0891 h_dt Entries 335 Mean 0.08868 RMS 0.09145 Underflow 0 Overflow 0 h_dt Entries 335 Mean 0.08868 RMS 0.09145 Underflow 0 Overflow 0 30◦− 45◦ h_gm Entries 8804 Mean 0.5009 RMS 0.2806 Underflow 0 Overflow 0 C 0 0.10.20.30.40.50.60.70.80.9 1 0 20 40 60 80 100 120 140 160 180 200 h_gm Entries 8804 Mean 0.5009 RMS 0.2806 Underflow 0 Overflow 0 h_dt Entries 456 Mean 0.1196 RMS 0.1306 Underflow 0 Overflow 0 h_dt Entries 456 Mean 0.1196 RMS 0.1306 Underflow 0 Overflow 0 Eγ > 1019 eV data photon MC, E−2 spectrumCalculations
Search region:
I Egamma > 1019 eV 1395 events
I 45◦ < θ < 60◦ 335 events
I C > 0.5 1 event
I Poisson 95% upper limit: ≤ 5.14 events
I Total exposure: Atotal= 158 km2 sr yr
I Fγ< 3.3· 10−2 km−2sr−1yr−1 (95% CL)
Photon flux limits
18 18.5 19 19.5 20 Log EmineV 35.5 36 36.5 37 37.5 38 Log H E 2 F Γ H eV 2 km -2 yr -1 sr -1 LL A A PA PA PA Y Y Y TA TA ICRCPRELIMINARY
Photon fraction and flux limits
Fraction limits 18 18.5 19 19.5 20 Log EmineV 0.1 1 10 100 ΕΓ ,% 0.1 1 10 100 A A A PAO-SD PAO-SD PAO-SD HP HP AY Y Y AH PAO-H PAO-H PAO-H PAO-H Y Y Y Flux limits 18 18.5 19 19.5 20 Log EmineV 35.5 36 36.5 37 37.5 38 Log H E 2F Γ H eV 2km -2yr -1sr -1LL A A PA PA PA Y Y Y TA TA ICRC PRELIMINARY I GZK prediction: γ< 1% for E > 1019 eV Gelmini,Kalashev,Semikoz, JCAP 0711 (2007)I Photons may be detected in the near future (depends on astrophysics parameters)
Constraints on parameters of Superheavy dark matter
21.5 22 22.5 23 Log10HMXeVL -17. -16.5 -16. Log 10 H FSH m -2 sr -1 s -1 L 21.5 22 22.5 23 Log10HMXeVL -17. -16.5 -16. Log 10 H FSH m -2 sr -1 s -1 LFSH – flux of SHDM-produced cosmic rays E > 1020 eV above thick line – excluded by spectral fits
shaded area – allowed by spectrum and γ limits
⇒SHDM decay may not be the source of all UHECRs
Lorentz invariance violation tests 1/2
I LIV is proposed by Coleman & Glashow to suppress GZK
process Phys.Rev.D59,1999
I If LI is broken, threshold of GZK reaction may be upshifted p + γ2.7K→ ∆(1232)
I If we can prove that GZK reaction takes place, we have a constraint on LIV parameters
I One approach to confirm GZK reaction is to observe secondary photons
Lorentz invariance violation tests 2/2
I If LI is broken for photons in form
ω2= k2+ ξnk2(k/MPl)n
pair production on CMB
γ + γCMB→ e++ e−
may be suppressed by kinematics and photons will propagate through large distances.
I Observed photon flux will contradict existing photon limits if |ξ1| & 10−14or ξ2 .−10−6.
Galaverni, Sigl, Phys.Rev.Lett.100, 2008
Conclusions
I TA is a large scale detector operating in the northern hemisphere
I Results on spectrum, composition and anisotropy are presented
I UHECR sources are not yet discovered
I Good chance to detect GZK photons in the midrange
future (3 - 5 years)