1 CANGAROO-III Masaki Mori* for the CANGAROO team *ICRR, The University of Tokyo ICRR internal talk, October 19, 2005

2 CANGAROO team  University of Adelaide  Australian National University  Ibaraki University  Ibaraki Prefectural University  Konan University  Kyoto University  STE Lab, Nagoya University  National Astronomical Observatory of Japan  Kitasato University  Shinshu University  Institute of Space and Astronautical Science  Tokai University  ICRR, University of Tokyo  Yamagata University  Yamanashi Gakuin University

3 T2 T4 T3 T1 Woomera: 2004 March

4 Basic specifications of telescopes T2  Location: 3106 ’ S, 13647 ’ E 160m a.s.l.  Telescope: 114 80cm FRP mirrors (57m 2, Al surface) 8m focal length Alt-azimuth mount  Camera: T1: 552ch (2.7 FOV) T2,T3,T4: 427ch (4 FOV)  Electronics: TDC+ADC

5 History of CANGAROO-III : Construction : Observation start : Expansion to 10m : Observation : Tuning T1 T2 T3 T Stereo observation 2005 Global trigger system 12 Maintenance 8

6 Global trigger system d 100m t=d/c < 500ns variable Coincidence Opt.fiber 650ns Event number Trigger Telescopes Turnaround ~2.5  s Wait time ~5s Telescopes Opt.fiber Trigger  Before: “ software trigger ” Each telescopes triggered independently  Now: “ hardware stereo ” Requires at least 2 telescopes  If no coincidence  Reset Dead time 1/ m

7 ICRC2005 contributed papers  K. Nishijima: Status of the CANGAROO-III Project (OG27, oral)  T. Tanimori: Recent status of the analyses for stereoscopic observations with the CANGAROO-III telescopes (OG22, oral)  Y. Sakamoto: Search for Very High Energy Gamma-Rays from Active Galactic Nuclei with CANGAROO-III Telescope (OG23, poster)  S. Kabuki: Observation of TeV Gamma-ray from the Active Radio Galaxy Centaurus A with CANGAROO-III (OG23, poster)  T. Yoshikoshi: Performance of the Imaging Atmospheric Cherenkov Telescope System of CANGAROO-III (OG27, poster)  M. Ohishi: Very high energy gamma-ray observations of the Galactic plane with the CANGAROO-III telescopes (OG21, oral)  R. Kiuchi: Optical measurements by cooled CCD cameras for CANGAROO-III (OG27, oral)  T. Nakamori: Stereoscopic observations with the CANGAROO-III telescopes at the large zenith angles (OG22, oral)

8 Stereo observation Target Intersection Angular resolution 0.25deg  0.1 deg Energy resolution 30%  15% Better S/N (no local muons)

9 Large zenith angle observation of the Crab NARROWER Higher energy threshold ~1TeV Bad intersection accuracy Far coresmall angle bad accuracy Events ONLY

10 Unfortunate situation for the Crab Showers from the Crab  The oldest T1 has higher energy threshold and bad efficiency for stereo observation  Only T2/T3/T4 are used for stereo analysis  Stereo baseline becomes short for the Crab observation at large zenith angles

11 IP constraint fit Blank : After IP fit Hatched : Before IP fit Search intersection point (IP) by minimizing  2 so that width along shower axis to be minimum and armlength to be near the expected value ( =0.75, Mesh size o ) Monte Carlo

12  /h separation by Fisher discriminant  Linear combination of image parameters ( x i )  Difference between signal () and background (h)  Determine  i which maximize separation (solvable using correlation matrix)  With calculated  i for a known source, the (appropriately normalized) combination F could be the “ Fisher discriminant ” for other sources.  We use widths and lengths of multiple telescopes for image parameters. R.A. Fisher, Annals of Eugenics, 7 (1936) 179 F D  h

13 Crab signal (3) T2 & T3 890 min (Dec.2003) Points: On-source Hatched: Off-source Plot : observation Solid : MC gamma Dashed : background IP fit + F > excess events 5.8 sigma R.Enomoto et al., ApJ in press (2005)

14 Crab spectrum Preliminary Flux (cm -2 s -1 ) Energy (TeV) HEGRA Excess event map Angular resolution ~ 0.23 deg R.Enomoto et al., ApJ in press (2005)

15 Cen A: the nearest AGN No signal seen S. Kabuki, Ph.D. thesis Preliminary Observation term Observation time (T2-T3) Observation time (T2-T4) Average zenith angle 15 – 28 Mar min414 min17 degree 15 – 28 Apr min468 min17 degree Total1047 min882 min Elliptical Radio galaxy Fanaroff-Riley type I “Misaligned” BL Lac (~ 60 o ) Distance 3.5 Mpc (z= ) Near infrared image 2MASS m CANGAROO-III Angular resolution

16 Cen A: flux limit Energy bin (GeV)  upper limit flux ( cm -2 sec -1 ) Preliminary Crab Upper limit: ~7% Crab Note that this is a highly variable source, and the TeV claim in 70 ’ s was based on observations during its flaring activity. CANGAROO-III S. Kabuki, Ph.D. thesis

17 Galactic diffuse emission Milagro 4.5 detection

18 Observation of the Galactic disk Obs.termtel.pair b=0 b=-3 b=+3 2004JunT2-T JunT2-T Obs.termtel.pairONOFF 2004JunT2-T JunT2-T AugT2-T AugT2-T l= Jun l= Jun/Aug (Obs.time in minutes) T2-T3 T2-T4 EL>45deg E th ~600 GeV M. Ohishi, Ph.D. thesis

19 Galactic disk scan result No excess at the disk! (expected ~1deg) Preliminary l =19.5 M. Ohishi, Ph.D. thesis

20 SNR RX J [stereo] Excess event map T2 & T3 wobble 1,204 min. (2004 Jan/Feb) Off region: Vela or out of SNR  2 from SNR center Fisher discriminant ONOFF R.Enomoto et al., to be submitted

21 SN1006 [stereo] NE-rim pointing (2004 May) T2, T3 & T4 long ON/OFF 1,625 min. ON, 1,738 min. OFF T2 & T3 results on likelihood Independent analysis (Fisher disc.) Gamma-ray energy (TeV) T.Tanimori et al., ICRC2005

22 PSR [stereo] Pulsar pointing (2004 May) T2, T3 & T4 long ON/OFF 1,625 min. ON, 1,738 min. OFF T2 & T3 results on square cut Independent analysis (Fisher disc.) T.Tanimori et al., ICRC2005

23 Vela [stereo] Pulsar pointing (2004 Jan/Feb) T2 & T3 wobble, 1,311 min. Fisher discriminant Pulsar position  2 from Vela X center Vela X nebula (HESS, ICRC2005) R.Enomoto et al., ApJ in press (2005)

24 Summary  We have been carrying out stereo observations of sub-TeV gamma-rays since 2004 March.  Stereo analysis are developed and the flux of the Crab is consistent with other results.  Upper limits were set for gamma-rays from Cen A and the Galactic disk.  The extended profile of SNR RX J is observed.  Preliminary results on SN1006, PSR and Vela pulsar show no gamma-ray signal.

25 Crab signal (1) Nov 2003, T2 & T3

26 Crab signal (2) Angular resolution for the Crab (stereo)

27 CANGAROO-I results: summary  SNR/Pulsar Crab  ApJL ’ 94  SNR SN1006  ApJL ’ 98  SNR RX J  A&AL ’ 00  SNR W28  A&A ’ 00  Pulsar PSR  ApJL ’ 95  Pulsar Vela  ApJL ’ 97  Pulsar PSR  ApJ ’ 00  Pulsar PSR  (Ph.D. ’ 97)  AGNs: PKS , EXO , PKS , PKS  A&A ’ 98  Blazars: PKS and PKS  A&A ’ 99  Radio galaxy Cen A  (Proc. ’ 99) Signal Publish   Signal:  detected,  upper limit,  marginal, v: variable H.E.S.S.        v 

28 CANGAROO-II results: summary  SNR RX J  Nature’02  Blazar Mrk421  ApJL ’ 02  Starburst galaxy NGC253  A&AL ’ 03  SNR SN1987A  ApJL ’ 03  Galactic Center  ApJL ’ 04  Pulsar binary PSR /SS2883  ApJ ’ 04  SNR RX J (Vela Jr.)  ApJL ’ 05 Signal Publish  Signal:  detected,  upper limit, v: variable H.E.S.S.     v 