TeV gamma-ray observation of RCW86 with the CANGAROO-II telescope

TeV gamma-ray observation ofTeV gamma-ray observation of RCW86 RCW86

with thewith the CANGAROO-II CANGAROO-II telescopetelescope

WATANABE Shio (Kyoto university)

for the CANGAROO Collaboration

Contents•The CANGAROO telescope•Motivation•Observation •Analysis •Result •Summary

28th ICRC Tsukuba, 3 August 2003

Site: Woomera, South

Australia

CCollaboration of ollaboration of AAustralia and ustralia and NNipponippon

for a for a GAGAmma mma RRay ay OObservatory in the bservatory in the OOutbackutback

University of AdelaideAustralian National UniversityIbaraki UniversityIbaraki Prefectural University of Health

ScienceInstitute for Cosmic Ray Research,

U. TokyoInstitute of Space and Astronautical ScienceKitasato UniversityKonan University

Kyoto UniversityNational Astronomical Observatory

of JapanOsaka City UniversityShinshu UniversitySTE Laboratory, Nagoya UniversityTokai UniversityTokyo Institute of Technology Yamagata UniversityYamanashi Gakuin University

Australian Institutes : 2 & Japanese Institutes : 15

31°06’ S 136°47’ E 160m a.s.l.

—— = — C maxUphoton

dE 4 2 dt I.C. 3

—— = — C max —dE 4 2 B2

dt Synch.3 2

TeV gamma-ray from SNRsTeV gamma-ray from SNRs

0 decay

スペクトルの形に違いSynchrotron

SN1006 NE rim

RX J1713.7-3946 Inverse Compton scattering

=5e13

Naito 1999Naito 1999

Enomoto et al. . 2002

Type-II SNR Diameter 0.8 deg. Distance 2.5 kpc Age ~2000 yr

Supernova Remnant Supernova Remnant RCW86RCW86

ObservedLow temperatureHigh temperatureNon-thermal Bamba et al. 2000

0.5 1 2 5 10[keV]

RCW86 SW shell

Image by ASCASW shell

Red: 0.7 - 2 keVBlue: 2 - 10 keV

Bamba et al. 2000

Multi wavelength spectrumMulti wavelength spectrum

B < 15 µG

Detectable for CANGAROO-II

Radio

RCW86 SW-shellSN1006 NE-rim

X-ray(ASCA)

SN1006 CANGAROO-II 10m Hara et al.　 2001

Synchrotron

Inverse Compton scattering (estimated)

Synchrotron emission SN100610

Observation with CANGAROO Observation with CANGAROO

observation selected

ON 26h 23m 20h 29m

OFF 27h 46m 18h 05m

Strongest emission (E>2.0 keV)R.A. = 220.19Dec.=-62.67 (obs.@zenith ~ 32deg.)

2001 (March, April, May)

observation selected

ON 41h 11m 30h 08m

OFF 38h 37m 33h 49m

2002 (March, April)

Suffering from light pollution

Estimation of Threshold Estimation of Threshold EnergyEnergy

Energy threshold[events]

[TeV]

Generated allDetected

Eth 900GeV

32 – 40 degree(relatively large)

High energy threshold

Monte Carlo simulation Gamma-ray

photon index=2.5150 GeV – 15 TeV

Observation zenith angle

Imaging methodImaging method

SumADC -5000ch( -1 TeV)

5000-14000ch(1-2 TeV)

14000ch-(2 TeV- )

Distance 0.1-1.1 0.2-1.1 0.2-1.25

Length 0.05-0.2 0.09-0.25 0.1-0.35

Width 0.03-0.1 0.05-0.14 0.1-0.14

ADC>500(5.4 p.e) & T4a shower event calculate Image Parameter

Energy > 1 TeV (ADC>5000ch)

Excess events577±125(4.6)

Excess events-72±12 (0.6 )

Preliminary ResultPreliminary Result

No excess below 1 TeV inverse Compton scattering ?

Signal <15 deg. Normalize

>30 deg.

Energy < 1 TeV (ADC<5000ch)

Cosmic rayIndex=2.7

SummarySummary

• Supernova remnant RCW86 (emitting synchrotron X-ray) was observed with the CANGAROO-II telescope.

• Preliminarily, we found gamma-ray like events~4 sigma level (@Energy > 1 TeV). – We need more data to confirm this result.

• In this year, we took additional data.– More data

(~65 hours) – High quality

(Stereo observation; Enomoto OG2.5-6)• High Signal/Noise ratio • Lower energy region

Observation in 2003

March Telescope 1 Telescope 2

ON 27h 29m 26h 53m

OFF 23h 47m 20h 16m

April Telescope 1 Telescope 2

ON 42h 20m 37h 41m

OFF 39h 36m 35h 19m

Total Telescope 1 Telescope 2

ON 69h 49m 64h 37m

OFF 63h 23m 55h 35m

X-ray Observation by X-ray Observation by ChandraChandra

High resolution imaging detector

Soft band(<2 keV): DiffusiveHard band(>2 keV): Filament

RCW86 SW shell by Chandra0.5-1 keV 1-2 keV 2-8 keV

Soft and hard regions are completely resolved.

Non-thermalThermal

Rho et al., 2002

Soft

Hard filament

Nearby Molecular Cloud

Red:thermal X-ray

(ROSAT)Contour:

molecular cloud

Multi wavelength spectrumMulti wavelength spectrum

Radio

RCW86 SW-shellSN1006 NE-rim

X-ray(ASCA)

SN1006 CANGAROO-II 10m Hara et al.　 2001

Synchrotron Inverse Compton scattering (estimated)

Cosmic rayIndex=2.7

Energy dependence of Energy dependence of Alpha distributionAlpha distribution

Signal <15 Normalize >30

Energy < 1 TeV 1 - 2 TeV 2 TeV -

424 ±98 events 4.3

117±73 events 1.6

-72±12 events 0.6