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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
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
Flu
x (p
hoto
ns/s
ec/k
eV)
(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 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) 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
2exp)(
E
E
cm
EAEQ e
e
ee
(-function approximation)
1
)(4
11)(
4
1~
)(
2
2
dE
dEEQ
d
VdE
dEEVQddE
EdF
ee
ee
Synchrotron/inverse Compton model
Source spectrum
Differential flux of photonsfrom the energy loss of electron
:
:
:
:
:
:
:
max
d
V
E
m
E
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
E
cc
E
dt
dE
E
3
4
3
41
1~
1
2
2
1
max
2
2
1
2
2
3
222
exp
3
2
4
)(
CMB
e
ee
CMBCMBT
e
IC
IC
E
E
E
cm
cm
E
cm
Ec
cm
A
d
V
dE
EdF
:
:
:
CMB
T
e
Lorentz factor of electrons
Cross section of Thomson scatteringEnergy density of CMB
Synchrotron process
hcm
eBEE
esyncCMB 422
329.0
2
1
max
2
2
1
2
2
3
222
exp
3
2
4
)(
sync
e
ee
syncBT
e
sync
sync
E
E
E
cm
cm
E
cm
Ec
cm
A
d
V
dE
EdF
8
2BBCMB
One-zone model: syncIC VV
EGRET:Diffuse emissionUpper limits (counts + 2)
Two-zone model:
V
X
TeVsyncIC V
VVV
51074
X
TeV
V
V
“Simple”
Difficulty in two-zone model
54
3
max
3
max
1074104.2
'5.0
24.0
X
TeV
X
TeV
V
V
410
X
TeV
V
VTeVE 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
EFdEF
E
20
0
dE
EEdEjdEnEF pE
EE pppp
p
p
,4
max
min
ppp nEj )( to
max500 exp
10 p
pppp E
EE
erg
E
V
KEj
Intensity of protons
Differential cross section
dE
EEdNE
dE
EEd pp
p ,,
Low energy: isobar modelHigh energy: scaling model
Fitting parameters
0.2 maxE2
30
500
5.0/10
kpc
d
cmprotons
n
erg
EA
Data CANGAROO EGRET diffuse (upper limits)
DOF/2
DOFDOF // 2min
2
TeVE
A
1.3
8.1
max Best fit
8.15.0/10
2
30
500
kpc
d
cmprotons
n
erg
EA
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