Transcript 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
• (Personal) view ;
Problems, Riddles, and Questions raised;
which remain to be answered by further
observation with better sensitivities
• Prospects
A perspective map for TeV γ-ray study
E2dN/dE
TeV γ-ray emitter at
present
We are here
Mt “photon absorber”
hidden path
X-ray
sources
１０３eV
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
1012eV
1020eV
Frontier of TeV γ-ray astronomy ?
CollAboratioN for GAmma Ray
Observatory in the Outback
Motivation of CANGAROO?
• To open/establish
the ground-based
γ-ray astronomy at TeV energy
• Origin of cosmic rays ?
• Galactic sources ?
• To exploit the Southern sky
Location
Woomera, SA
Australia
(31°06’S,
136°47’E, 160
m a.s.l.)
evolution/history of CAＮGAROO Project
CANGAROO-II
7m (1999)
CANGAROO-III
T1,T2,T3 (20022003)
upgraded
CANGAROO-III
(2003-2004)
CANGAROO-I
3.8m (1992)
CANGAROO-III
T1 10m (2000)
CANGAROO-III Telescopes

light collecting dish
– area 57m2
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)
Y[m
]
Stereoscopic observation going
Impact Point Distribution
T2
T1
X[m]
By D. Nishida & H. Tanimura
Stereoscopic observation going
Trigger Timing Difference
20ns(rms)
Time(min)
By D. Nishida & H. Tanimura
CANGAROO-III has started
• Operation of four 10m
telescopes(since Mar, 2004)
• Stereoscopic Observation
T3
Sep. 2003 started
T2
Dec. 2002 started
T1
Since 2000
T4
Mar. 2004
Results and arguments
population of TeV sources
• pulsar nebulae; SNRs;
• other galaxies
• Diffuse emission (Galactic disc
emission)
in relevance to cosmic rays
• Blazars
• Other types of sources; e.g. Xray binaries
Models and observed data?
• 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
PSRJ1420-6048
TeV Gamma-ray sources
of pulsars and candidates
Crab
pulsed
Vela
unpulsed
.
E (erg/s)/4pd (cm)2
10 arcmin.
Vela
～60arcsec=0.15pc
Chandra ACIS(2000),
ASCA image
Unpulsed TeV
gamma-ray
emission from
young pulsars
with
synchrotron
nebula
PSR1509-58
PSRB1509-58
～200arcsec=4.3pc
Chandra ACIS(2000),
PSRB1706-44
Period [sec]
Thompson, Heidelberg WS, 2000
Roberts,Romani,Johnston (2001) ApJ 561: L187—L190.
Pulsars
PSR B1509-58
Alpha Distribution
Events
Crab
Under Analysis
Period :150 ms
Distance :4.4 kpc
Age :1.7×103 yr
Spin-down energy :
1.8×1037 erg/s
“Standard candle” is
observed as it should be
– Our telescope is
working properly!
C. Itoh, Ph.D. thesis (2003)
PSR B1706-44
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)
By Y. Miyashita
& N. Sakamoto
Alpha
TeV Gamma-ray sources of SNRs
and candidates
RX J1713.7-3946 （CANGAROO）
ASCA
SN1006 （CANGAROO）
RCW86（CANGAROO under analysis）
ASCA
ROSAT
Crab nebula
（”Standard candle”）
Chandra
・optical
Shell type SNRs with nonthermal X-ray emission are
detected in TeV region.
Chandra
Cas A （HEGRA）
ROSAT
RX J0852.0-4622
under analysis）
（CANGAROO
SNRs
RX J1713.7-3946
SN1006
Electron origin
Naito et al. AN 320 (1999)
Emission from
protons (p0)?
 Cosmic ray
origin?
Enomoto et al. Nature 416 (2002) 823
SNR RX J0852.0-4622:
(190 hrs in 2yrs) New TeV source ?
8o
Vela SNR
Gamma-ray signal
(ON-OFF)
7.4 excess
d~1kpc
Maximum
X-ray emission
2o
Katagiri, PhD (2004)
SNR RCW86:Under analysis
Red: 0.7 - 2 keV
Blue: 2 - 10 keV
RCW86 SW shell
Image by ASCA
Bamba et al. 2000
Energy < 1 TeV
(ADC<5000)
Energy > 1 TeV
(ADC>5000)
Signal events
-72±12 (-0.6)
Signal events
577±125(4.6)
Signal a < 15o
Normalize a > 30o
a
a
S. Watanabe et al., 28th ICRC (2003)
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
Blazars
Mkn421
active Energy spectrum
steeper than that
observed at E<10TeV.
However, marginally
significant excess
(4) observed at
E>20TeV  Cut off
energy:～8TeV
K. Okumura et al.,
ApJ. 579 (2002) L9
PKS 2005-489 ('00)
quiescent
PKS 2155-304 ('00 & '01)
quiescent
UL !
UL !
By T. Nakase
a source of
Galactic Center:
TeV γ-rays !
Alpha Distribution
Significance Map
9.8 excess
SgrA*(Massive Black Hole)
SgrA west,(Circum
nuclear disk)
Tsuchiya et al.,
ApJ, 606 L115 (2004)
SgrA East(SNR)
SgrA halo
Cluster of Galaxies 3EG J1234-1318
EGRET UnID source
Significance map
Possible cluster
A1555 EGRET
Kawasaki & Totani,
ApJ,576 (2002) 679
PSF
By T.Hattori
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?)
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
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
•
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.
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 toseem
ultimately
The
dark matter/energy
to rule the
universe,
and rule the universe, and
ultimately
the contact with the “Lord of Darkness” might be
interesting.
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”
Recent CANGAROO targets
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Signal
Pulsar PSR 1706-44

Pulsar Vela pulsar

SNR/Pulsar Crab

SNR SN1006

SNR RX J1713.7-3946
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SNR RX J0852-4622
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SNR RCW86

SNR SN1987A

Binary pulsar PSR 1259-63/SS2833

Galactic Center/Sgr A*

Galactic jet object SS433

Galaxy Small Magellanic Cloud
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Starburst galaxy NGC253
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AGN Mrk421
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AGN PKS2155-304, PKS2005-489

EGRET unID 3EG J1234-1318
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Publication
 (PhD 2003)
 (PhD 2002)
 (Nature2002)
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 (ApJL2003)
 (in press)
 (ApJL2004)
 (AAL02,AA03)
 (ApJL2002)
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Signal:  detected,  upper limit,  under analysis
Publish:  published,  in preparation
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
Examples of Events with T2
TDC
ADC
Scaler
Star