Status of CANGAROO III Akihiro Asahara ( Kyoto Univ.) CANGAROO expanded meeting 1.Introduction 2.Resent Results 3.Brand-new! CANGAROO T2 4.Stereo Analysis
Collaboration of Australia and Nippon for a GAmma Ray Observatory in the Outback An array of imaging atmospheric Cherenkov telescopesto detect high-energy gamma-rays from celestial objects in Woomera, Australia
CANGAROO team • University of Adelaide • Australian National University • Ibaraki University • Ibaraki Prefectural University • Kanagawa University • Konan University • Kyoto University • Nagoya University • National Astronomical Observatory of Japan • Osaka city University • The University of Tokyo (ICRR) • Shinshu University • Institute for Space and Aeronautical Science • Tokai University • Tokyo Institute of Technology • Yamagata University • Yamanashi Gakuin University 17 institutes join this project.
Observation Method Proton simulation Gamma-ray simulation Camera image
Observation Data (Crab Nebula) Alpha plot α distribution （simulation） ON run OFF run Residual Gamma Proton
CANGAROO 10m telescope 552ch PMTs • Upgraded to 10m in 2000 • 114 x 80cm CFRP mirror segments(first plastic-base mirror in the world!) • Focal length 8m • Alt-azimuth mount • 552ch imaging camera • Charge and timing electronics (March 2000)
TeV gamma-ray sky ~ 2002 Grade A CANGAROO FOV (El > 40 degree) Grade B Grade C
Red: Grade A Blue: Grade B Black: Grade C CANGAROO detected 7 sources TeV sources
SNR RX J1713.7-3946:emission from protons? • Hard to explain by emission from electrons (Brems, IC) • Emission from protons(0)? • Cosmic ray origin? Enomoto et al. Nature 2002
Starburst galaxy NGC 253 Multi-wave-length spectrum of Galactic Halo • New kind of TeV source • Similar in size to our own galaxy • Nearby spiral galaxy (2.4Mpc) • Broad emission region. Radio Itoh et al. A&AL 2002 Non-thermal radiation from Galactic Halo Itoh et al. ApJL 2003 Optical CANGAROO
Mrk 421: hint for cosmology? 5TeV Okumura et al. ApJL 2002 Emission above 20 TeV Fewer IR backgroun photons? Cosmology: galaxy formation
～10arcsec PSR 1706-44 • Peak intensity of detected TeV gamma-ray flux becomes ten times stronger than that of X-ray flux from the nebula. • TeV gamma-ray flux is difficult to explainbySync-IC (2.7k CMB) model in the nebula. The magnetic field is too week. Nebula Chandra ACIS Image (0.7-9 keV) Kushida, 2003, Ph. D thesis, Tokyo Inst. of Tech.
Finished On analysis On analysis On analysis Finished; In prep. Finished; In prep. On analysis On analysis On analysis Finished; In prep. On analysis On analysis On analysis On analysis On analysis On analysis Detected Other Targets Positive Upper limit Signal Status • SNR/Pulsar Crab • SNR SN 1006 • SNR RCW 86 • SNR RX J0852-4622 • SN 1987A • PSR 1259-63/SS2833 • PSR 1509-58 • PSR 1420-6048 • Vela pulsar • AGN PKS 2155-304, PKS 2005-489 • AGN PKS 0548-322 • EXO 055625-3838.6 • Galactic Center/Sgr A* • Galactic jet object SS433 • Galaxy The Small Magellanic Cloud • EGRET un-ID 3EG J1234-1318
CANGAROO-III project Caution! This is prospective image.
Time schedule 10m X 2 10m X 3 10m X 4 Observation Sep 2003 EXO 0556 RX J0852 RCW86 Stereo Targets SN1006 PSR 1706, RXJ 1713 ’04 ’03
Better angular resolution=0.25(One month observation)0.15(event by event) • Better energy resolutionE/E=30%15% Stereo observation And improvement of S/N ratio.
Merit of Stereo (1) Angular resolution • Single Telescope • ~0.25deg (one month observation) 0.05 deg (Stereo) • 10m X 2 Stereo Telescope • ~0.15deg (event by event) • ~0.05deg, or better than that!! • (one month observation) 0.25 deg (Single) TeV g-rays from shell-type SNRs Detailed mapping Of the emission region SN1006 significance map (CANGAROO 10m single)
Merit of Stereo (2) Stereo observation Effective area → ×0.8 S/N → ×6 ～7 (Enomoto et al. 2002) Alpha <15゜ 952±137events(6.9σ) 750±60 (12σ) 0.45<E(TeV)<6.25
Present status: Three 10m telescopes in Woomera Assembled in Dec. 2002 In operation since 2000 Started operation in Dec. 2002 T2 T3 T1
10m telescope No.2 (CANGAROO T2) • Completed in 2002 • Focal length 8m • Improved FRP mirror segments • 427ch imaging camera • Placed Hex; FOV 4.0 • HV imposed on each PMTs 4.0°
T2 event samples ADC TDC PMT hit Scaler Star Info.
Stereo Analysis DAQ phase I (current): Both telescopes are operated Independently. • Attached information on T2 data: • Trigger delay time (1nsec resolution). • Current event number of T1. Stereo analysis is conducted on off-line.
Stereo Trigger rate T1 rate after cut ~2Hz T1: trigger rate ~ 40Hz T2: trigger rate ~ 30Hz Coincidence ~ 2Hz The Stereo trigger rate is limited by T1.
Trigger delay time -1.05150.02 ns/min Measured by TDC -1.105 ns/min Calculated from Telescope movement OFF-line stereo analysis is working well.
ADC spectrum of T2 Red: ADC spectrum of T2 Blue: ADC spectrum of T2 made from the data triggered by T1 Pink: Power law function (index -2.7) Eth(blue) / Eth(red) ~ 4 T2 Energy threshold ~ 200GeV
Stereo Events TDC (hit timing) ADC (light intensity) T1 Distribution of Arrival directions (not ready) T2
0.01Crab (@200GeV) Typical Observation time (ON-OFF total): 80h/month Sensitivity of CANGAROO III
Summary Stereo Observation Started in Dec 2002!! Telescope 2 is in expected performance. Energy threshold ~ 200GeV • Telescope 3 will be started in Aug 2003. • Telescope 4 will be started in Dec 2003. Sensitivity will become ~ 0.01Crab (@200GeV, 20 hour). CANGAROO team published 3 papers in 2002. • RXJ1713 (Enomoto et al. , Nature) • NGC253 (Itoh et al. , A&A) • Mrk 421 (Okumura et al. , ApJ) And we have several papers in prep.