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CANGAROO and VHE γ -ray Astronomy: Past, present and future

Frontier Science 2004, Villa Mondragone. CANGAROO and VHE γ -ray Astronomy: Past, present and future. Tadashi Kifune (Shinshu Univ.). Outline of the talk. What is CANGAROO ? Present status ： CANGAROO III now with 4 telescopes in stereo mode Results so far obtained

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CANGAROO and VHE γ -ray Astronomy: Past, present and future

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  1. Frontier Science 2004, Villa Mondragone CANGAROO and VHE γ-ray Astronomy:Past, present and future Tadashi Kifune (Shinshu Univ.)

  2. Outline of the talk • What is CANGAROO? • Present status ： CANGAROO III now with 4 telescopes in stereo mode • Results so far obtained • (Personal) view ; Problems, Riddles, and Questions raised; which remain to be answered by further observation with better sensitivities • Prospects

  3. A perspective map for TeV γ-ray study E2dN/dE Mt “photon absorber” We are here TeV γ-ray emitter at present X-ray sources hidden path Oasis ? beyond “GZK pass” Enlarge the “concave” area better sensitivity/resolution, to find more sources and new populations, However, energy is low compared with CRs 　　１０３eV 1012eV 1020eV Frontier of TeV γ-ray astronomy ?

  4. CollAboratioN for GAmma Ray Observatory in the Outback • To open/establish the ground-based γ-ray astronomy at TeV energy • Origin of cosmic rays ? • Galactic sources ? • To exploit the Southern sky Motivation of CANGAROO? • Location • Woomera, SA Australia • (31°06’S, 136°47’E, 160 m a.s.l.)

  5. evolution/history of CAＮGAROO Project CANGAROO-II 7m (1999) CANGAROO-III T1,T2,T3 (2002-2003) upgraded CANGAROO-III (2003-2004) CANGAROO-I 3.8m (1992) CANGAROO-III T1 10m (2000)

  6. CANGAROO-III Telescopes • light collecting dish • area57m2 114 spherical mirrors(0.8 m f) • paraboloid with focal length 8m • CarbonFRP GlassFRP • Camera • number of pixels：427 ch(552ch) • field of view： 4.0°( 2.7°) • Threshold of gamma-rays •  200 GeV ( 400 GeV) ( 80 Hz)

  7. Stereoscopic observation goingImpact Point Distribution Y[m] T2 T1 X[m] By D. Nishida & H. Tanimura

  8. 20ns(rms) Time Difference (ns) Time(min) Stereoscopic observation going Trigger Timing Difference By D. Nishida & H. Tanimura

  9. CANGAROO-III has started • Operation of four 10m telescopes(since Mar, 2004) • Stereoscopic Observation T3 T2 T1 T4 Sep. 2003 started Since 2000 Dec. 2002 started Mar. 2004

  10. pulsar nebulae; SNRs; other galaxies Diffuse emission (Galactic disc emission) in relevance to cosmic rays Blazars Other types of sources; e.g. X-ray binaries consistency between synchrotron and inverse-Compton model Progenitor of γ-rays; e± or p Emission map in SNR: point-like or extended ? Identification with other radiation bands Results and arguments Models and observed data? population of TeV sources

  11. PSRJ1420-6048 pulsed Vela unpulsed ～60arcsec=0.15pc 10 arcmin. Chandra ACIS(2000), E (erg/s)/4pd (cm)2 ASCA image PSR1509-58 Unpulsed TeV gamma-ray emission from young pulsars with synchrotron nebula . PSRB1509-58 ～200arcsec=4.3pc Chandra ACIS(2000), TeV Gamma-ray sources of pulsars and candidates Crab Vela PSRB1706-44 Period [sec] Thompson, Heidelberg WS, 2000 Roberts,Romani,Johnston (2001) ApJ 561: L187—L190.

  12. PSR B1509-58 Crab Pulsars Alpha Distribution Events Under Analysis C. Itoh, Ph.D. thesis (2003) Very preliminary! Period :150 ms Distance :4.4 kpc Age :1.7×103 yr Spin-down energy :1.8×1037 erg/s By Y. Miyashita & N. Sakamoto Alpha PSR B1706-44 “Standard candle” is observed as it should be – Our telescope is working properly! TeV gamma-ray flux is difficult to be explained by Sync-IC model (2.7K CMB) in the nebula. Period :102 ms Distance :1.8 kpc Age :1.7×104 yr Spin-down energy :3.4×1036 erg/s J. Kushida, Ph.D. thesis (2003)

  13. RCW86（CANGAROO under analysis） ROSAT Shell type SNRs with non-thermal X-ray emission are detected in TeV region. ROSAT RX J0852.0-4622 （CANGAROO under analysis） TeV Gamma-ray sources of SNRs and candidates RX J1713.7-3946 （CANGAROO） SN1006（CANGAROO） ASCA ASCA Crab nebula （”Standard candle”） Chandra ・optical Chandra Cas A （HEGRA）

  14. SNRs RX J1713.7-3946 Emission fromprotons (0)? • Cosmic ray origin? SN1006 Electron origin Naito et al. AN 320 (1999) Enomoto et al. Nature 416 (2002) 823

  15. SNR RX J0852.0-4622:(190 hrs in 2yrs) New TeV source ? 8o Vela SNR Gamma-ray signal (ON-OFF) 7.4 excess Preliminary! d~1kpc Maximum X-ray emission 2o Katagiri, PhD (2004)

  16. Red: 0.7 - 2 keV Blue: 2 - 10 keV RCW86 SW shell SNR RCW86:Under analysis Energy > 1 TeV (ADC>5000) Energy < 1 TeV (ADC<5000) Preliminary! Image byASCA Bamba et al. 2000 Signal events -72±12 (-0.6s) Signal events 577±125(4.6s) Signal a < 15o Normalize a > 30o a a S. Watanabe et al., 28th ICRC (2003)

  17. NGC253 • distance : 2.5 Mpc • Enhanced star formation rate • High SN rate : 0.1 - 0.3/yr • Higher CR production by factor 10-100 C. Itoh et al. A&AL 2002

  18. Mkn421 Blazars active Energy spectrum steeper than that observed at E<10TeV. However, marginally significant excess (4s) observed at E>20TeV Cut off energy:～8TeV K. Okumura et al., ApJ. 579 (2002) L9 PKS 2005-489('00) PKS 2155-304('00 & '01) quiescent quiescent UL ! UL ! By T. Nakase

  19. a source of TeV γ-rays ! 9.8 excess Galactic Center: Significance Map Alpha Distribution SgrA*(Massive Black Hole) SgrA west,(Circum nuclear disk) Tsuchiya et al., ApJ, 606 L115 (2004) SgrA halo SgrA East(SNR)

  20. Significance map Possible cluster EGRET A1555 PSF Cluster of Galaxies 3EG J1234-1318 EGRET UnID source Preliminary! Kawasaki & Totani, ApJ,576 (2002) 679 Preliminary! Preliminary! By T.Hattori

  21. A “tough” but exciting time to overcome Earlier detection to be confirmed • SN1006: H.E.S.S. Upper Limit < 8% of CANGAROO flux • How about other objects? H.E.S.S., with better sensitivity at lower threshold energy, detected TeV sources from which CANGAROO had difficulty to obtain signal in spite of long-continued efforts : • PKS2155-304 (necessary to be blessed by outburst) • PSR1259-63 (emission only near at periastron?)

  22. What will follow from now on(my private view) ? (4.6±0.6±1.4)×10-12cm-2s-1: E>1.7±0.5 TeV (2.4±0.6±0.7)×10-12cm-2s-1: E>3±1 TeV (Tanimori et al. ApJ 497 L25(1998) • Repeated observation of CANGAROO is going on with better ΔӨ and reduced Ethreshold • Details of H.E.S.S. result? Estimation of the flux is affected by several factors: • ΔӨ : depending on if radiation is regarded as from “point source” or “extended” • Spectral shape as a function of location • (Effects due to sky noise of background photons?) • ………. The efforts for solving the above “problems” hopefully lead to • better knowledge on the spectral shape and morphology of TeV γ-ray emission • Confirmation of newer sources with improved sensitivity

  23. summary summar CANGAROO and “origin of cosmic rays”: Observational evidences? • The 1st Step was taken to clarify CR origin: acceleration site? proton or electron? B- field? • Next Stage: what remain to be done ΔӨ --- acceleration region and structure of SNR ? absolute flux of extended emission ? spectral shape ------ emission map of sources • Max Acc energy: Emax to compare with ~1015eV (knee of CRs) Approach from Σ(point-like sources) from diffuse emission corresponding to CR spectrum • Galactic disc emission • Other galaxies

  24. Conclusion • “Problems” and mysteries to be studied and clarified by using CANGAOO III telescopes. • Beyond challenging CR origin, Jets, Black holes, dark matter, …. • We further need to seek for larger telescope of better sensitivity.

  25. Appendix: from “Lord of the ring” (J.R.R. Torkien) One Ring to rule them all. One Ring to find them. One Ring to bring them all and in the Darkness bind them. • Many projects and/or One big project ? • One major topic ? The dark matter/energy seem to ultimately rule the universe, and the contact with the “Lord of Darkness” might be interesting. The dark matter/energy seem to ultimately rule the universe, and

  26. TeV γ-ray astronomy as “frontier science” “Towards a major atmospheric Cherenkov imaging detector?” “Towards a major topic?” • Frontiers of instrumentation E, ΔE, ΔӨ , …. ΔΩ, … distance, … • Frontiers of Topics : objects peculiar to TeV γ-rays populations and number of samples “Origin of cosmic rays”to more generally “energetic processes in the Universe”

  27. Recent CANGAROO targets Signal Publication • Pulsar PSR 1706-44(PhD 2003) • Pulsar Vela pulsar • SNR/Pulsar Crab • SNR SN1006(PhD 2002) • SNR RX J1713.7-3946(Nature2002) • SNR RX J0852-4622 • SNR RCW86 • SNR SN1987A(ApJL2003) • Binary pulsar PSR 1259-63/SS2833(in press) • Galactic Center/Sgr A*(ApJL2004) • Galactic jet object SS433 • Galaxy Small Magellanic Cloud • Starburst galaxy NGC253(AAL02,AA03) • AGN Mrk421(ApJL2002) • AGN PKS2155-304, PKS2005-489 • EGRET unID 3EG J1234-1318 Signal: detected, upper limit, under analysis Publish: published, in preparation

  28. 1) TeV sources made steadily increasing, “as expected”. 2) However, with several results “unexpected”. 3) “next generation IACTs” CANGAROOIII, VERITAS, MAGIC, H.S.S.S. in Namibia, southern Africa

  29. Examples of Events with T2 TDC ADC Scaler Star

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