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

Observations of SNR RX J0852.0-2644 with

CANGAROO-II telescope

Kyoto, Dec., 16, 2003H. Katagiri, R. Enomoto, M. Mori, L. Ksenofontov

Institute for cosmic ray research (ICRR)

Introduction

But claimed by Butt et al. and Reimer et al. …

TeV detection from SNRs SN1006 (CANGAROO) => e or p Cas-A (HEGRA) => p RX J1713.2-3946 (CANGAROO) => p

RX J1713.2-3946

Inconclusive problem

Need further evidence

NANTEN supports our results (Fukui et al.)

ROSAT X-ray image

8o

Vela SNR Maximum X-ray emission

2oSNR RX J0852.0-4622

Flux

(pho

tons

/sec

/keV

)

(0.4<E<2.0keV)

Energy (keV)1 5 10

Radio

Parkes 4.85GHz survey image(gray scale)

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

Spectral index=0.400.15

Molecular clouds

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.

Vela region8

CO integratedIntensity map

NANTEN

EGRET

No point sourcein CANGAROO FOV

Effected by Vela SNRand pulsar (2.5deg. distance)

Profiles of RX J0852.0-4622

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

Type II SNR Density within SNR

n<2.9×10-2 D1-1/2 f--1/2 (g cm-2)

low => stellar-wind cavity

Ti lineColumn density from X-rayangular size

Distance < 500pc Age 1000 yr

CANGAROO observationsNW 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) 89hStereoscopic observation with 2 telescopes (2003) => under analysis

CANGAROO-II 10m IACT in Australia

%30E

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 data4.Cut low elevation

data 5.Cut hot pixels

N.S.B.

Image analysis

Source position

Distance

Width

Length

Alpha

Width and Length are theR.M.S. of the ADC countson each axis.

In order to reject cosmic ray events as a noise

Gamma-ray signal

(ON-OFF)8.0

Results

Morphology

Consistent with X-ray and radio

PSFSeems to be Point source

Blue:our dataRed:ASCA X-ray dataGreen:4850MHz continuum

max

2

2 exp)(EE

cmEAEQ e

e

ee

(-function approximation)

1)(

4

11)(4

1~)(

2

2

dEdEEQ

dV

dEdEEVQ

ddEEdF

ee

ee

Synchrotron/inverse Compton model

Source spectrum

Differential flux of photonsfrom the energy loss of electron

:::

::::

max

dVE

mE

e

e Electron energyMass of the electronSpectral indexMaximum accelerated energy of electronsVolume of emission regionDistance from the earthAverage time that an electron ( ) emits a photon ( )eE E

Inverse Compton process

CMBe EE 2

CMB

CMBTCMBeT

IC

e

IC

Ecc

E

dtdE

E

34

341

1~1

2

21

max

2

21

2

23

222

exp

32

4)(

CMB

e

ee

CMBCMBT

e

IC

IC

EE

Ecm

cmE

cmEc

cmA

dV

dEEdF

::

:

CMB

T

e

Lorentz factor of electrons

Cross section of Thomson scatteringEnergy density of CMB

Synchrotron processh

cmeBEE

esyncCMB 422

329.0

21

max

2

21

2

23

222

exp

32

4)(

sync

e

ee

syncBT

e

sync

sync

EE

Ecm

cmE

cmE

ccmA

dV

dEEdF

8

2BBCMB

One-zone model: syncIC VV

EGRET:Diffuse emissionUpper limits (counts + 2)

Two-zone model:

V

X

TeVsyncIC V

VVV

51074

X

TeV

VV

“Simple”

Difficulty in two-zone model

54

3

max

3

max

1074104.2'5.0

24.0

X

TeV

X

TeV

VV

410

X

TeV

VVTeVE 4max

5.2GB 2500

X-ray

TeV

0.2GB 10

Need Chandra, XMM-newton results (filaments ?)and more exact discussion (escape time, energy loss process)

(Aharonian, Atoyan, and Kifune)

Too many parameters!!!

Two-zone model:

model (Naito-Takahara model)0

22min2

mE

EFdEFE

20

0

dEEEd

EjdEnEF pE

EE ppppp

p

,4

max

min

ppp nEj )( to

max500 exp

10 p

pppp E

EE

ergE

VKEj

Intensity of protons

Differential cross section

dEEEdN

EdE

EEd pp

p ,,

Low energy: isobar modelHigh energy: scaling model

Fitting parameters

0.2 maxE2

30

500

5.0/10

kpcd

cmprotonsn

ergEA

Data CANGAROO EGRET diffuse (upper limits)

DOF/2

DOFDOF // 2min

2

TeVEA

1.38.1

max Best fit

8.15.0/10

2

30

500

kpcd

cmprotonsn

ergEA

30 /505000 cmprotonsn

ergE 50480 1010/

Best fit model

:solid angle of the observed part

SummaryOur 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

TeVE 73max TeVE 100max Factor is 1.5, but it does not change conclusion.

RX J1713.2-3946

Full calculation Delta function approximation