Observations of snr rx j0852 0 2644 with cangaroo ii telescope
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Observations of SNR RX J0852.0-2644 with CANGAROO-II telescope. Kyoto, Dec., 16, 2003 H. Katagiri, R. Enomoto, M. Mori, L. Ksenofontov Institute for cosmic ray research (ICRR). Introduction. TeV  detection from SNRs SN1006 (CANGAROO) => e or p Cas-A (HEGRA) => p

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Observations of SNR RX J0852.0-2644 with CANGAROO-II telescope

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Observations of SNR RX J0852.0-2644 with CANGAROO-II telescope

Kyoto, Dec., 16, 2003

H. Katagiri, R. Enomoto,

M. Mori, L. Ksenofontov

Institute for cosmic ray research (ICRR)


TeV  detection from SNRs

SN1006 (CANGAROO) => e or p

Cas-A (HEGRA) => p

RX J1713.2-3946 (CANGAROO) => p

RX J1713.2-3946

But claimed by Butt et al.

and Reimer et al. …

NANTEN supports our results (Fukui et al.)

Inconclusive problem

Need further evidence

SNR RX J0852.0-4622


ROSAT X-ray image



X-ray emission

Vela SNR

Flux (photons/sec/keV)





Energy (keV)


  • Weak emissionSν at 1GHz =47±12Jy=>same as RXJ1713,SN1006.

  • Spectral index=0.400.15

Parkes 4.85GHz survey image(gray scale)

Molecular clouds

CO integrated

Intensity map


Vela region

Vela SNR taken by NANTEN and soft X-ray image(gray scale) taken by ROSAT.

Around Vela Molecular ridge taken by the Colombia University 1.2m millimeter-wave telescope.


Effected by Vela SNR

and pulsar (2.5deg. distance)

No point source


Profiles of RX J0852.0-4622

Ti line

Column density from X-ray

angular size

Distance < 500pc

Age 1000 yr

  • On the galactic plane => molecular clouds(l,b)=(266.2,-1.2)

  • Type II SNR

  • Density within SNR n<2.9×10-2D1-1/2 f--1/2 (g cm-2) low => stellar-wind cavity

CANGAROO observations

  • NW rim with maximum X-ray emission (,)=(132.25,-45.65) Minimum zenith angle 14.6o => Energy threshold 500GeV

  • Observation term 2002 and 2003 ON 97h OFF(background) 89h

  • Stereoscopic observation with 2 telescopes (2003) => under analysis


IACT in Australia

Procedure of analysis


1.Select clustered event

=>remove N.S.B.

2.Arrival time of signal

Almost the same time at shower event

3.Cut cloudy data

4.Cut low elevation data

5.Cut hot pixels

Image analysis

In order to reject cosmic ray events as a noise





Source position

Width and Length are the

R.M.S. of the ADC counts

on each axis.


Gamma-ray signal




Blue:our data

Red:ASCA X-ray data

Green:4850MHz continuum

Consistent with X-ray and radio


Seems to be Point source

Synchrotron/inverse Compton model

Source spectrum

Differential flux of photons

from the energy loss of electron

(-function approximation)

Electron energy

Mass of the electron

Spectral index

Maximum accelerated energy of electrons

Volume of emission region

Distance from the earth

Average time that an electron ( ) emits a photon ( )

Inverse Compton process

Lorentz factor of electrons

Cross section of Thomson scattering

Energy density of CMB

Synchrotron process

One-zone model:

  • EGRET:

  • Diffuse emission

  • Upper limits

    (counts + 2)


Two-zone model:

Difficulty in two-zone model

Two-zone model:



(Aharonian, Atoyan, and Kifune)

Too many parameters!!!

Need Chandra, XMM-newton results (filaments ?)

and more exact discussion (escape time, energy loss process)

model (Naito-Takahara model)


Intensity of protons

Differential cross section

Low energy: isobar model

High energy: scaling model

Fitting parameters



EGRET diffuse (upper limits)

Best fit

Best fit model

:solid angle of the observed part


  • Our data strongly favour gamma rays from neutral pions and low flux from synchrotron/inverse Compton.

  • NANTEN data will give us more physics.

  • Fine structure allow two-zone model.Chandra and XMM-newton resutlts are needed.

Check of approximation

RX J1713.2-3946

Full calculation

Delta function approximation

Factor is 1.5, but it does not change conclusion.

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