CANGAROO-III

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
Woomera 2004 March
T2 T4 T3 T1
4
Basic specifications of telescopes

• Location
• 31?06S, 136?47E
• 160m a.s.l.
• Telescope
• 114? 80cm? FRP mirrors
• (57m2, Al surface)
• 8m focal length
• Alt-azimuth mount
• Camera
• T1 552ch (2.7? FOV)
• T2,T3,T4 427ch (4? FOV)
• Electronics
• TDCADC

T2
5
History of CANGAROO-III
2000
1999
2001
2002
2003
2004
2005
3
3
11
7
3
1
6
12
8
12
T1
T2
Stereo observation
Global trigger system
Maintenance
T3
T4
Construction
Observation
Observation start
Tuning
Expansion to 10m
6
Global trigger system
d

• Before software trigger
• Each telescopes triggered independently
• Now hardware stereo
• Requires at least 2 telescopes
• If no coincidence ? Reset
• Dead time ?1/100

100m
?td/c lt 500ns variable
Opt.fiber
650ns
150m
Telescopes
Telescopes
Opt.fiber
Turnaround 2.5?s
Trigger
Wait time 5?s
Trigger
Event number
Coincidence
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
9
Large zenith angle observation of the Crab
Higher energy threshold 1TeV Bad intersection
accuracy
NARROWER
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
Search intersection point (IP) by minimizing ?2
so that width along shower axis to be minimum and
armlength to be near the expected value
(ltArmlengthgt0.75, Mesh size 0.025o)
Monte Carlo
Blank After IP fit Hatched Before IP fit
12
?/h separation by Fisher discriminant

• Linear combination of image parameters (xi)
• 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
13
Crab signal (3)
R.Enomoto et al., ApJ in press (2005)
Points On-source Hatched Off-source
IP fit F gt 0
Plot observation Solid MC gamma Dashed
background
203 excess events 5.8 sigma

• T2 T3
• 890 min (Dec.2003)

14
Crab spectrum
R.Enomoto et al., ApJ in press (2005)
Excess event map
Angular resolution 0.23 deg
15
Cen A the nearest AGN
S. Kabuki, Ph.D. thesis

• Elliptical
• Radio galaxy
• Fanaroff-Riley type I
• Misaligned BL Lac ( 60o)
• Distance 3.5 Mpc (z0.00183)

No signal seen
Near infrared image 2MASS 1.2-2.17?m
Observation term Observation time (T2-T3) Observation time (T2-T4) Average zenith angle
15 28 Mar 2004 603 min 414 min 17 degree
15 28 Apr 2004 444 min 468 min 17 degree
Preliminary
Total 1047 min 882 min
16
Cen A flux limit
S. Kabuki, Ph.D. thesis
Preliminary
Crab
CANGAROO-III
Upper limit 7 Crab
Note that this is a highly variable source, and
the TeV claim in 70s was based on observations
during its flaring activity.
Energy bin (GeV) 530 700 1120
2 ? upper limit flux (?10-12cm-2sec-1) 3.2 1.8 0.9
17
Galactic diffuse emission
Milagro 4.5? detection
18
Observation of the Galactic disk
M. Ohishi, Ph.D. thesis
l-19.5 2004Jun
(Obs.time in minutes)
Obs.term tel.pair b0? b-3? b3?
2004Jun T2-T3 635.3 322.3 292.9
2004Jun T2-T4 380.0 201.9 192.5
l13 2004Jun/Aug
Obs.term tel.pair ON OFF
2004Jun T2-T3 289.6 340.0
2004Jun T2-T4 199.5 270.0
2004Aug T2-T3 224.9 183.6
2004Aug T2-T4 280.0 85.7
ELgt45deg Eth 600 GeV
19
Galactic disk scan result
M. Ohishi, Ph.D. thesis
l 19.5?
Preliminary
No excess at the disk! (expected ?1deg)
20
SNR RX J0852.0-4622 stereo
R.Enomoto et al., to be submitted

• T2 T3 wobble
• 1,204 min. (2004 Jan/Feb)
• Off region Vela or out of SNR

Excess event map
Fisher discriminant
ON
OFF
?2 from SNR center
21
SN1006 stereo
T.Tanimori et al., ICRC2005

• 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)
22
PSR 1706-44 stereo
T.Tanimori et al., ICRC2005

• 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.)

23
Vela stereo
R.Enomoto et al., ApJ in press (2005)

• Pulsar pointing (2004 Jan/Feb)
• T2 T3 wobble, 1,311 min.
• Fisher discriminant

Pulsar position
?2 from Vela X center
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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 J0852.0-4622 is
  observed.
• Preliminary results on SN1006, PSR 1706-44 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
Signal Publish
H.E.S.S. ? ? ? ? ? ? ? ?v ?

• SNR/Pulsar Crab ? ApJL94
• SNR SN1006 ? ApJL98
• SNR RX J1713.7-3946 ? AAL00
• SNR W28 ?
  AA00
• Pulsar PSR 1706-44 ? ApJL95
• Pulsar Vela ? ApJL97
• Pulsar PSR 1509-58 ? ApJ00
• Pulsar PSR 1055-52
  ? (Ph.D.97)
• AGNs PKS0521-365, EXO0423.4-0840, PKS0548-322,
  PKS2316-423
  ? AA98
• Blazars PKS2005-489 and PKS2155-304
  ?
  AA99
• Radio galaxy Cen A ?
  (Proc.99)

Signal ? detected, ? upper limit, ? marginal, v
variable
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CANGAROO-II results summary
Signal Publish
H.E.S.S. ? ? ? ? ? ?v ?

• SNR RX J1713.7-3946 ? Nature02
• Blazar Mrk421 ? ApJL02
• Starburst galaxy NGC253 ? AAL03
• SNR SN1987A ? ApJL03
• Galactic Center ? ApJL04
• Pulsar binary PSR 1259-63/SS2883 ? ApJ04
• SNR RX J0852.0-4622 (Vela Jr.) ? ApJL05

Signal ? detected, ? upper limit, v variable