Results of the Telescope Array experiment

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 Aida}2_{, M Allen}1_{, R Azuma}3_{, E Barcikowski}1_{, JW Belz}1_{, T Benno}4_{, DR Bergman}1_,

SA Blake1_{, O Brusova}1_{, R Cady}1_{, BG Cheon}6_{, J Chiba}7_{, M Chikawa}4_{, EJ Cho}6_{, LS Cho}8_{, WR Cho}8_{, F Cohen}9_,

K Doura4_{, C Ebeling}1_{, H Fujii}10_{, T Fujii}11_{, T Fukuda}3_{, M Fukushima}9,22_{, D Gorbunov}12_{, W Hanlon}1_,

K Hayashi3_{, Y Hayashi}11_{, N Hayashida}9_{, K Hibino}13_{, K Hiyama}9_{, K Honda}2_{, G Hughes}5_{, T Iguchi}3_,

D Ikeda9_{, K Ikuta}2_{, SJJ Innemee}5_{, N Inoue}14_{, T Ishii}2_{, R Ishimori}3_{, D Ivanov}5_{, S Iwamoto}2_{, CCH Jui}1_,

K Kadota15_{, F Kakimoto}3_{, O Kalashev}12_{, T Kanbe}2_{, H Kang}16_{, K Kasahara}17_{, H Kawai}18_{, S Kawakami}11_,

S Kawana14_{, E Kido}9_{, BG Kim}19_{, HB Kim}6_{, JH Kim}6_{, JH Kim}20_{, A Kitsugi}9_{, K Kobayashi}7_{, H Koers}21_,

Y Kondo9_{, V Kuzmin}12_{, YJ Kwon}8_{, JH Lim}16_{, SI Lim}19_{, S Machida}3_{, K Martens}22_{, J Martineau}1_{, T Matsuda}10_,

T Matsuyama11_{, JN Matthews}1_{, M Minamino}11_{, K Miyata}7_{, H Miyauchi}11_{, Y Murano}3_{, T Nakamura}23_,

SW Nam19_{, T Nonaka}9_{, S Ogio}11_{, M Ohnishi}9_{, H Ohoka}9_{, T Okuda}11_{, A Oshima}11_{, S Ozawa}17_{, IH Park}19_,

D Rodriguez1_{, SY Roh}20_{, G Rubtsov}12_{, D Ryu}20_{, H Sagawa}9_{, N Sakurai}9_{, LM Scott}5_{, PD Shah}1_{, T Shibata}9_,

H Shimodaira9_{, BK Shin}6_{, JD Smith}1_{, P Sokolsky}1_{, TJ Sonley}1_{, RW Springer}1_{, BT Stokes}5_{, SR Stratton}5_,

S Suzuki10_{, Y Takahashi}9_{, M Takeda}9_{, A Taketa}9_{, M Takita}9_{, Y Tameda}3_{, H Tanaka}11_{, K Tanaka}24_,

M Tanaka10_{, JR Thomas}1_{, SB Thomas}1_{, GB Thomson}1_{, P Tinyakov}12,21_{, I Tkachev}12_{, H Tokuno}9_{, T Tomida}2_,

R Torii9_{, S Troitsky}12_{, Y Tsunesada}3_{, Y Tsuyuguchi}2_{, Y Uchihori}25_{, S Udo}13_{, H Ukai}2_{, B Van Klaveren}1_,

Y Wada14_{, M Wood}1_{, T Yamakawa}9_{, Y Yamakawa}9_{, H Yamaoka}10_{, J Yang}19_{, S Yoshida}18_{, H Yoshii}26_{, Z Zundel}1

1_{University of Utah,} 2_{University of Yamanashi,} 3_{Tokyo Institute of Technology,} 4_{Kinki University,}

5_{Rutgers University,} 6_{Hanyang University,} 7_{Tokyo University of Science,} 8_{Yonsei University,}

9_{Institute for Cosmic Ray Research, University of Tokyo,} 10_{Institute of Particle and Nuclear Studies, KEK,}

11_{Osaka City University,} 12_{Institute for Nuclear Research of the Russian Academy of Sciences,}

13_{Kanagawa University,} 14_{Saitama University,} 15_{Tokyo City University,} 16_{Pusan National University,}

17_{Waseda University,} 18_{Chiba University} 19_{Ewha Womans University,} 20_{Chungnam National University,}

21_{University Libre de Bruxelles,} 22_{University of Tokyo,} 23_{Kochi University,} 24_{Hiroshima City University,}

Telescope Array observatory

I 507 SD’s, S = 3m2

I 3 FD’s

TA surface detector

M. 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

T.Shibata, UHECR-2010, Nagoya Fist run: September 2010

Telescope Array physics objectives

Study of UHECR E_{& 10}18 _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_{& 10}19.7eV. p + γ_{2.7K→ 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 = E_SD/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

Yakutsk array result on chemical composition

Possible 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

?

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_{∈ [θ}1, 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

Linsley curvature “a”: data vs photon MC

Event-by-event method

I For each event with curvature a_obs we select photon MC events compatible by arrival direction and S₈₀₀.

I We calculate curvature distribution function f_γ(a) for MC photons I Let’s define C = aobs Z −∞ f_γ(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

Calculations

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: A_total= 158 km2 sr yr

I F_γ< 3.3_{· 10}−2 km−2sr−1yr−1 (95% CL)

Photon flux limits

PRELIMINARY

Photon fraction and flux limits

I Photons may be detected in the near future (depends on astrophysics parameters)

Constraints on parameters of Superheavy dark matter

F_SH – 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 + γ_{2.7K→ ∆(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)