Suzaku Observation of SN 1006: Is it the

1
Suzaku Observation of SN 1006 Is it the
youngest Galactic SNR?
Hiroya Yamaguchi, Katsuji Koyama, Hiroshi
Nakajima (Kyoto Univ.), Aya Bamba, and Junko S.
Hiraga (RIKEN) Email(HY) hiroya_at_cr.scphys.kyoto-u
.ac.jp
Abstract We observed whole region of SN1006 with
the Suzaku satellite in the PV-phase. In this
poster, we present the results of spectral
analysis of the Southeast region of the SNR,
where the thermal plasma emission is dominant.
With great performance of X-ray Imaging
Spectrometers (XIS) onboard Suzaku, we
successfully detected the K-shell emission lines
from heavy elements (S, Ar, Ca, and Fe) of the
ejecta for the first time, and this result
confirmed that SN1006 is Type Ia SNR. The
centroid energy of the Fe-K line is 6.43keV,
which can be interpreted the ionization state of
Fe is Ne-like condition. We compared the O-K
spectrum with that of Cygnus Loop, and found the
electron temperature of SN1006 is higher than
that of Cygnus Loop, but ionization temperature
of SN1006 is much lower than that of Cygnus Loop.
We also compared the spectrum with Cas A, and
found both the ionization temperature and
electron temperature of SN1006 are lower than
that of Cas A. This result means the ionization
age of SN1006 is much younger than that of Cas A,
and is the consequence of that SN1006 exploded
on the significantly low-dense interstellar
space. The radial dependence of the centroid
energy of the emission lines implies the reverse
shock of SN1006 moves outward to the rim of the
SNR. All results suggest SN1006 is the remarkable
SNR in the significantly early phase of the
evolution.

1. Suzaku Image

2.2 O-K Complex
BI
Although SN1006 is 20 times younger than Cygnus
Loop (2104 yr), their structures of O-K lines
are very similar each other. However the Suzaku
spectra penetrated their essential differences
the spectrum of Cygnus Loop consists of strong
He-like O-Ka and H-like O-Ka, but that of SN1006
is dominated by He-like O-K series (a, ß, ?, d,
and so on). This fact suggests the electron
temperature of SN1006 is much higher than that
of Cygnus Loop, but ionization temperature of
SN1006 is much lower than that of Cygnus Loop.
Thanks to high quantum efficiency and moderate
energy resolution in low energy band of XIS
onboard Suzaku, we succeed to divide a thermal
component from strong non-thermal (synchrotron)
emission. In this poster, we discuss the thermal
plasma component only. About the non-thermal
component, see the presentation by Bamba et al.
0.57 keV (He-like O-Ka) Thermal dominant
3.0-5.5 keV Non-thermal dominant
2. Thermal Spectrum
Since the thermal plasma emission is especially
bright in the Southeast region of SN1006, we
extracted spectra from the polygonal region as
shown in the left figure. We detected the
K-shell emission lines from heavy elements, S,
Ar, Ca, and Fe, for the first time. The spectra
strongly suggests the origin of SN1006 is type Ia
supernova.
Ne
Mg
Si
O
S
Fe
Ar
BI (XIS1) Average of 3FIs
Ca
Cr?
2.3 Mg-Si-S Band
The Cas A spectrum consists of strong He-Ka,
He-Kß, and H-Ka lines from Mg, Si, and S. On
the other hand, H-Ka lines are very weak in the
SN1006 spectrum. Furthermore, the Si and S
K-shell lines consist of not only He-Ka but also
Ne-Ka. SN1006 is 3 times older than Cas A
(300yr), but the spectra suggests the
ionization temperature of SN1006 are much lower
than that of Cas A.
3FIs
Centroid energy of the emission Lines
Ionization state is different between each
element. The centroid energy of Mg K-shell line
is consistent with that of He-like K line. On
the other hand, ionization state of Fe is much
lower than He-like, and is able to be considered
as Ne-like.
Neutral (eV) Data (eV) He-like (eV)
Mg-Ka 1254 134513 1340
Si-Ka 1730 182624 1850
S-Ka 2307 236545 2450
Ar-Ka 2957 3026126 3120
Ca-Ka 3690 3738287 3890
Fe-Ka 6400 64301913 6680
Mg
Si
Red Cas A Black SN1006
S
The electron temperature of SN1006 (1keV) also
lower than that of Cas A (2-3keV), because
He-Kß lines are scarcely visible in the SN1006
spectrum. It can be interpreted that the thermal
equilibrium between ions and electrons has not
achieved enough on SN1006 (Tion gtgt Te). This is
the consequence of that SN1006 exploded in the
significantly low-dense interstellar space. The
ionization age of SN1006 is younger than that of
Cas A (, Kepler and Tycho)!
statistical error ? ? systematic error
2.1 Fe-K Band
We fitted a 5-10keV spectrum with VNEI (v1.1)
model. The abundance of Fe is relatively low,
however if the continuum component is dominated
by non-thermal emission or blast-wave component,
the abundance becomes more high. Therefore the
value should be considered as the lower limit
of the abundance.
Average of 3FIs
kTe 5.1 (gt2.7) keV net 3.9 (0.4-8.0) E9 cm-3
s Fe 2.9 (1.3-6.2) solar
SN1006 is the youngest SNR in our Galaxy!
3. Radial Dependence
0. Japanese historical record of SN1006
We divided the Southeast quadrant of SN1006 into
4 regions as shown in the left figure, and
investigated the radial dependence of the
centroid energy of the emission lines. Then we
found the centroids are lower in the outer region
of the SNR than the inner as shown in the
bottom-left figure. This result suggests the
ionization age is the youngest at the outer most
region of the SNR. We can conclude that the
reverse shock of SN1006 moves outward to the rim
of the SNR, and the ejecta are just being heated
by the shock at the rim.
Meigetsuki (This page was written in 11/8,
1230.)
???? Teika Fujiwara (1162-1241) The noble of
ancient Japan
The ancient samples of guest stars.
Guest stars comets, novae, and supernovae They
were believed as the predictions of disasters.
By fitting with VNEI model, we investigated the
distribution of the metal abundances. As shown in
the bottom-right figure, the distribution of Fe
is concentrated in the inner part of the SNR more
significantly than the other elements.
?? (kiquan)
Radial dependence of the centroid energy
Distribution of the metal abundance
SN1006
Crab
3C58
About SN1006 ??? ???? ???? ?? ??? ??? ???? ???
???? ?????? ?? ??????? ??? In the reign-period
of Ichijo-In, April 2nd, 3rd year of Kanko ( May
1st, 1006), a great guest star appeared within
the constellation Kikan(Imperial Guards). It
was very bright like Mars, and visible in the
southern sky every night. One possibility was
the star ofKijin-Shogun ( Chariots and
General) suddenly lighten?
Mg
Mg
???? (Kijin-Shogun) corresponds to Lupus?
Si
Si
Fe
S