Origin of the 6.4 keV line of the
Galactic Ridge X-ray Emission (GRXE)
Takeshi Go Tsuru (Kyoto University)
M.Nobukawa, S.G.Ryu, S.Nakashima,
K.Koyama (Kyoto Univ.), H.Uchiyama (Univ. of Tokyo)

20120131_Suzaku_AO7_KeyProject_EastRidge_Hearing_E_v31.key

6.4 keV line emission from Ridge

2

1.00

EW map of the 6.4 keV line near GC
No region with such high EW has been discovered except the GC.
B

A

E

C

0.000

Sgr D

000

0.000

359.000

357.000

Ridge-1.000

Suzaku found that 6.4 keV line emission
with nearly equal EW uniformly exist.

extend toward theGalactic ridge.

-2.000Key Quesstion.
What is the origin of this 6.4 keV line
emission in the Galactic ridge ?

3of
4Asymmetric
3
2 Distribution
10-1 6.4keV-2 line-3
Galactic longitude l (deg)-4

6.4 keV line flux

East (left) Ridge GC

XRNWest (right) Ridge

2

2

Intensity (1e-7 photons /s /cm /arcmin )I (6.4 keV) l profile @ b=-0.046 pm 0.05 deg

10

KP

?

1

10-1

4

3

2
1
0
-1
-2
Galactic Longitude l (deg)

-3

-4

4

Asymmetric Distribution of 6.4keV line
Suzaku : 6.4 / 6.7keV flux ratio

ASCA : Fe line center

Uchiyama+11

Maeda89

2.5
Sgr B2[6.4 keV]/[6.7 keV]

2
Sgr B1

1.5

SgrC

1

?

?

0.5

Sgr C
Sgr B

0
3

2

1
0
-1
-2
Galactic longitude (degree)-3

Suzaku flux ratio between the two lines
also shows asymmetric distribution.

Fe center energies distributeasymmetrically.

These results suggest the source of the
6.4 keV emission line distribute asymmetrically.

5

6.4 keV flux - 6.7 keV flux2

6.4 keV (ph/cm /s/arcmin )GC and Ridge
XRN
|l| =
scatter
1.5-4°
〜5

10

10

KP

-7

-8

•

•

?

10

•
•

>4°
-8

diffuse origin.
6.4 and 6.7 keV lines havedifferent origins
Their fluxes have ascattered correlation.
Ridge
The correlation is on
the natural extension
from the GC.
The 6.4 keV line fluxes
also scatter.

•

GC

2

10

-6

• GC
• 6.4 keV line emission has

-7

-6

10
10
2
2
6.7 keV (ph/cm /s/arcmin )• The expected KP data

seem to be on the lineof XRNe.

6

Single Origin ? or + Extra Source ?

• In the GC, the EWs are different

1000

GC

•

800

KP (Single)

600

KP (+ Extra)
Ridge

400

?

200

?

0

EW of 6.7 keV line (eV)

Galactic center

0

200
400
600
800
EW of 6.4 keV line (eV)from point to point.
This is because Fe emission lines
are mixture of multiple origins.

Objective 1
See if the plots of EW6.4 andEW6.7 concentrate in a single
point or not.

Examine if the spatial
distribution of the 6.4 keVline emission is symmetric or1000 asymmetric with respect to
the GC.

Case A : Single Origin (point source ?)Case B :+ Extra Source (diffuse ?)Start with Case B...

I

7
102

6.4 keV line emission correlates with MCs
4

3

2
1
0
-1
-2
Galactic longitude l (deg)

-4

deg

6.4 keV line flux

22

Intensity (1e-7 photons /s /cm /arcmin )I (6.4 keV) l profile @ b=-0.046 pm 0.05

-3

10

?

1

10-1

4

3

2
1
0
-1
-2
Galactic Longitude l (deg)-3-4Intensity (K km/s )13CO (NANTEN, Takeuchi+10)
102

10
4

3

2
1
0
-1
-2
Galactic longitude l (deg)

-3

-4

8

Strong 6.4 keV line emission from Clump 2
ASCA : Fe line centerNo. 2, 1998

GALACTIC CENTER CO SUR

12CO (Oka+98)

Maeda89

?
Sgr C
Sgr B

l = 3.5° exhibits
especially strong
6.4 keV line

l = 3.2° “Clump 2”
Objective 2
Search of correlation with MCs.
Objective 3
Determination of the ionizing particle.

9

Candidates for the ionizing particles• 6.4 keV flux ~1e-7 ph/cm2/sec/arcmin2 is expected in the KP observing region• XRN (X-ray Reflection Nebula)• Already seen in the GC.
• Sgr A* Lx(Sgr A*) ~10^41 ergs/s• LECRp (Low Energy Cosmic Ray Proton)• NH ~ 1e+24cm-2 (observed at Clump 2)• Up > 75eV/cm3 ← equipartition with B > 50μG at R<400pc (Crocker+11)~0.5e-7 ph/cm2/sec/arcmin2• LECRe (Low Energy Cosmic Ray Electron)• cf. Valinia+00• Ue~1 eV/cm3 x NH〜1e+23 cm-2
〜1e-7 ph/cm2/sec/arcmin2

All the three
processes are
possible.

10

EW(6.4) of the 6.4 keV component 【GC】

•EWs are different from

1000

GC

point to point

800
600

•

400

•Successfully fit the data

200

1.2keV0

EW of 6.7 keV line (eV)

Galactic center

0

200
400
600
800
EW of 6.4 keV line (eV)1000

with a line.
The emission is resolved
into 6.4 keV- and 6.7 keVrelated components.

•The intercept is the EWof the 6.4 keV line
emission against thecontinuum of the 6.4
keV-component.

•EW = 1.2keV → XRN

Apply this method to the Ridge data.

1000

Ridge

• We are unable to fit the line

600

800

only with existing data.

• Adding the KP data allows us to400

Ridge KP

200?

obtain the correlation line.

obtain !

0

200

400
600
800
6.4 (eV)line (eV)
EW ofEW
6.4keV• Obtain EW(6.4) of the 6.4
keV- component.

0

EW of EW
6.7keVline (eV)
6.7 (eV)

EW(6.4) of the 6.4 keV component【Ridge】

111000• Referring to the value, we

determine the ionizing particle.

12

Difference between XRN, LECRe and LECRp
Neutral Iron Line from Sgr B2 by Subrelativistic Protons

LECRe vs LECRp
102
Dogiel+11

XRN vs LECR

bombardment
X-ray
reﬂection
Inc Electronident
EW (keV)
X- EW(keV)〜0.3-0.6
ray〜1-1.5
BremssThomson
ScatterNH 〜1021(cm-2)
NH 〜1024(cm-2)

510

EW (keV)

3]

p
1
e

6.4
keV 0.1
6.4 7.1
7.1 keV0-4 -3 -2
-1
XRN: large EWSpectral Index
Fig. 2. Equivalent width of the K˛ line for the solar abundanceFig. 1. Cross section of electron and proton bremsstrahlung radiation&
deep
absorption
producedby electrons 〜(thick 300
solid line) and600
protons (thinsolid line
at the energy 6.4 keV, d!br =dEX (dashed line), and the cross-sections
LECRe
eV
2

!K of K˛ production for electron (thick solid line) and proton (thinsolid line). Here, E 0 = Ee for electrons and E 0 = (me =mp )Ep for
protons. Also, !K equals 0.3 and " is taken to be twice solar. The data

LECR: shallow absorption

for injection energy Einj = 80 MeV, dashed line for injection energy
Einj = 50 MeV) as a function of the spectral index, #.

LECRp 〜 500 - 3000 eV

13

If XRNSgr A* Luminosity (ergs/s)

1042
1041

Light Curve of Sgr A*

in 10 years(Gillessen+12)？

？ Clump 2

1040
1039
Sgr B, C
38
10
1037
1036
1035
1034
1033
-1000
Past

Sgr A

Direct observation
with Chandra-100
Time (yr)-10Present

Reveal the Activity of Sgr A* (SMBH) in 2000 years.

14

LECRe vs LECRpe or p
ASTRO-H
SXS	
  (μ-­‐calorimeter)e- (keV)σ∼0 eVp (MeV)σ∼10 eV

Cosmic Ray spectrum
log(number	
  density)

EW

6.4keV？

observe	
  for	  the	
  ﬁrst	  Eme

GeV/TeV
p?

keV	
  	
  	
  	
  	
  	
  	
  MeV	
  	
  	
  	
  	
  	
  	
  GeV	
  	
  	
  	
  	
  	
  	
  	
  TeV

Line widthconclusive evidence

Total amaount ofenergy of CR,
Spectrum,
Spacial distribution

15

0.1
10−3

10−3

6

7
Energy (keV)

Active Binaries

8

19eV

0.01

415eV

14 pointings
5

Sum of AB stars

380eV

0.01

235eV
Count s−1

Ridge

l*=1−2 dgree b*=0 degree

Counts s−1

0.1

Single Origin = Point Source Origin of 6.4 keV line
(apart from 6.7 keV line)

9

6.7keV is from Active Binaries
6.4keV is from CVs
Continuum of ABs reduces
EW of 6.4 keV line from CVs

7 AB
5

6

CVs

7
Energy (keV)

8

16 CVs in Yuasa’s D-Th
6.4keV ~110eV
6.7keV ~120eV(given by Yuasa-san)

9

Point Source Origin of 6.4 keV line
(apart from 6.7 keV line)• Mixture of ABs and CVs can explain only
the EWs on the line connecting the two.

800

• Simple mixture does not explain.
x3

600

EW of EW
6.7keVline (eV)
6.7 (eV)

1000

ABs & CVs vs Ridge

16

Ridge

• Abundance Measurements near GC• Giants (old >5x10^9yr) (bulge)
0.6 solar• Super Giants (young ~10^8yr) (< 12’)

400

ABs

x2

Fe(Local) x 2-3 is required.

1.3 - 2.0 solar

200• X-ray Plasma (ISM present) (< 20’)Fe ~ 1.2 solar (Nobukawa+10)

0

CVs
0

200

400
600
800
6.4 (eV)line (eV)
EW ofEW
6.4keV1000(note: Si, S = 1.9-2.5 solar)

Objective 4
Measurement of the Fe abundance gradient
toward the GC (along l) and Planes (along b).

17

Simulation : Spectrum and Correlation
1000

100ksec, Sum of 2FI

Galactic center
Galactic ridge
ABCV
100ks simulation

GC

200

103
2

400

EW6.7 (eV)

0.01

600

800

0.1

0

GRXE
0

2

0
Energy (keV)••CXB and NXB are already taken
into account in this simulation.
ΔEW6.4 = ± 39 eV (90%)ΔEW6.7 = ± 44 eV

200

400
600
EW6.4 (eV)

800

1000

• A simulation of the correlation.
(Scatter the data by hand)• Can determine EW(6.4) withenough accuracy to distinguishthe ionizing particles.

18“True” Legacy : Serendipitous Discoveries
Published or
Accepted 30

In prep. or
Submitted 5

Line Diagnostics of GCDX
Spectrum of Sgr A East
Hard X-Ray Emission the Arches Cluster
Diffuse Iron line of the Sgr B Region
Peculiar Hot Star in the GC
A Time Variable X-Ray Echo of Sgr B2
Diffuse Hard X-ray from the GC
New XRN and SNR in the Sgr B1 Region
X-Ray Flare of A-type Star HD 161084
SNR Candidate G359.79-0.26
New X-ray views of the Galactic Center
X-Ray Observations of the GC
Variable Neutral Iron Line in Sgr B2
Spatial Distribution of the GCDX
Suzaku Observations of Sgr D HII region
SAX J1748.2−2808
XRN in the Sgr C region
Dips/Absorption Lines of AXJ1745.6-2901
Thermal plasma near the Sgr C region
Iron lines from Galactic Ridge and GC
Superbubble
Face-on view of Sgr B2Foot-Point of the Radio Arc
Neutral Lines of Light Elements of Sgr A region
SNR and 6.4keV lines around the Great Annihilator
RRC of G359.1-0.5
Structures of Diffuse Emission from GCDX and GRDXK-Shell Emission of Neutral Iron Line from Sagittarius B2
Suzaku Discovery of Twin Thermal Plasma from the Tornado Nebula
Excited by Subrelativistic Protons
Spatial and Temporal Variations of the Diffuse Iron 6.4 keV Line in the Galactic Center Region
6.4 keV structure around Archies Cluster
A Time Variability of XRN in Sgr B2
3-D position of the Molecular Cloud of Sgr C in the GC
Spatial and Temporal Variations of the Diffuse Iron 6.4 keV Line in the Galactic Center Region
Broadband Spectral Decombosiion of the Galactic Ridge Emission

Doctor Thesis : 6

Koyama, Hyodo+
Koyama, Uchiyama+
Tsujimoto+
Koyama, Inui+
Hyodo+
Koyama, Inui+
Yuasa+
Nobukawa, Tsuru+
Miura+
Mori, Tsuru+
KoyamaKoyamaInui+
Koyama, Takikawa+
Sawada, Tsujimoto+Nobukawa+
Nakajima, Tsuru+
Hyodo+
Tsuru, Nobukawa+
Yamauchi+Mori, Tsuru+
Ryu, Tsuru+
Fukuoka+
Nobukawa, Tsuru+
Nakashima+
Ohnishi+Uchiyama+
Digiel+Sawada, Tsuru+
Chernysov+
Sawada+Nobukawa+
Ryu, Tsuru+
Chernyshov,Nobukawa+
T.Yuasa

Nakajima, Inui, Hyodo, Uchiyama, Nobukawa,Yuasa

7 New SNReS210

M. Sawada et al.

[Vol. 61,

Fig. 1. Wide-band (0.7–5.5 keV) smoothed images by the (a) XIS and (b) MOS shown with the logarithmic intensity scale. Overlaid green contoursin (a) are an 18 cm radio continuum map from the Very Large Array (VLA; Mehringer et al. 1998). The point source extraction aperture size andbackground accumulation region for PS2 and PS3 are shown in (b). See subsubsection 3.2.1 for details. For the XIS image, we merged events with thethree CCDs, subtracted the non-X-ray background (Tawa et al. 2008), corrected for the vignetting, and mosaicked the two fields with different exposure
times normalized. The fields of view are shown with two solid squares with 180 in length. For the MOS image, we merged two CCDs and mosaicked thetwo fields with normalized exposures. The fields are shown with two circles with 300 in diameter.

by external X-ray irradiation (Murakami et al. 2000). H II
regions are also an emerging class of diffuse X-ray sources
with a similar spatial scale. They show a variety of spectral
shapes, including soft thermal (Townsley et al. 2003; Hyodo
et al. 2008), hard thermal (Moffat et al. 2002; Ezoe et al. 2006),
and nonthermal (Wolk et al. 2002; Law & Yusef-Zadeh 2004;
Wang et al. 2006; Tsujimoto et al. 2007; Ezoe et al. 2006) emission. In addition to the X-ray emission, the measurement of the
X-ray absorption gives a constraint on the distance and hence
the physical scale of extended objects.
Several X-ray observations were reported in the Sgr D
region. In a BeppoSAX study (Sidoli et al. 2001), diffuse X-ray
emission was significantly detected from the Sgr D SNR andmarginally detected from the Sgr D H II complex. In an ASCA
study (Sakano et al. 2002), the image was plagued by straylights from a nearby bright source and was unsuitable to searchfor diffuse X-ray sources. In an XMM-Newton study (Sidoli
et al. 2006), dozens of point sources were identified, but nodiffuse emission was detected presumably due to high background. The possible diffuse X-ray detection by BeppoSAX in
the Sgr D H II complex has not been confirmed and no spectral
information exists for this source.
We conducted X-ray observations of the Sgr D H II complex
using the X-ray Imaging Spectrometer (XIS: Koyama et al.
2007a) onboard Suzaku (Mitsuda et al. 2007). The low background of XIS makes it particularly well-suited for finding
diffuse sources of low surface brightness and yielding theirhigh signal-to-noise ratio spectra. Indeed, a series of XIS

studies in the GC region identified several new SNRs andirradiated GMCs (Koyama et al. 2007b; Mori et al. 2008;
Nobukawa et al. 2008) and reported detailed spectroscopy of an
H II region (Tsujimoto et al. 2007). Upon the confirmation of
the previously claimed marginal diffuse detection in the Sgr D
H II complex, we further aim to construct the X-ray spectrum
which gives important insights into the origin of the emission
and the entire complex.
Here, we present a significant detection of diffuse X-ray
emission from the Sgr D H II complex with the Suzaku XIS.
High signal-to-noise ratio spectra were obtained from two
different diffuse sources. We discuss their X-ray characteristics and their association with sources observed in our study
using the 100-m Green Bank Telescope (GBT) and in otherarchived multiwavelength data sets. Based on these data, we
propose a new view of the Sgr D H II complex. In this paper,
we supplement the Suzaku data with those taken by XMMNewton in order to evaluate the contribution of point sources
to the diffuse emission. Throughout this paper, we use east andwest in the Galactic longitude direction, and north and south in
the Galactic latitude direction for simplicity.

13 New XRNe

2. Observations
2.1. Suzaku
We used two XIS fields covering the Sgr D H II complex in
the Suzaku GC mapping project (table 1). We hereafter call thetwo fields as north and south fields (figure 1a). The north field5 New Types of objects
Super Bubble
Super Bubble

H. Mori et al.

7 New SNRe
S210

[Vol. 61,

ChimneyTsuru+09“Chimney”

the Chimney

M. Sawada et al.

RRC-SNR

Tornado[Vol. 61,

0.0b

Sgr A*-0.2

G359.41-0.12

359.4

359.6
0

0.05

0.1

0.15

0.2

0.25

0.3

359.2

l
0.35

0.4

0.45

0.5

0.55

4 Unexpected Phenomena ・ New Perspectives
Fig. 1. Wide-band (0.7–5.5 keV) smoothed images by the (a) XIS and (b) MOS shown with the logarithmic intensity scale. Overlaid green contours

g. 5. GC mosaic images of He-like sulfur
K˛-lineandcontinuumHe-likemap
andH-like
The etimages
binned32 ! aperture
32 pixels
and thein (a)
are an 18(a),cm radio
fromthe Veryiron
LargeK˛-lines
Array (VLA;(b).
Mehringeral. 1998).were
The pointsourceby
extraction
size andregionfor PS2and PS3 are withshown !
in (b).
subsubsection
3.2.1 for details.
XISvignetting
image, we merged
eventsofwith
The exposure
time For
andthetheeffectthetheXRTs
ntinuum fluxes were then subtracted (seebackgroundtext) andaccumulation
the images
weresmoothed= 1See0.66.
three CCDs, subtracted the non-X-ray background (Tawa et al. 2008), corrected for the vignetting, and mosaicked the two fields with different exposure
re corrected. The XIS field of view is indicatedby a red polygon. The GC-ring spectrum was extracted from the elliptical arc-like region encircled
times normalized. The fields of view are shown with two solid squares with 180 in length. For the MOS image, we merged two CCDs and mosaicked thefields with
exposures.
The fields
are shownthe
withsource-extraction
two circles with 300 in diameter.
h solid curves. The background region istwoshown
bynormalized
a dashed
polygonexcludingregion and an ellipse with a red slash.

X-ray Tomography

by external X-ray irradiation (Murakami et al. 2000). H II studies in the GC region identified several new SNRs andregions are also an emerging class of diffuse X-ray sources irradiated GMCs (Koyama et al. 2007b; Mori et al. 2008;
with werea similarsummed
spatial scale.
They show a variety
spectralet al.indicates2008) and reported
spectroscopyof an hasalized by the effective area, andtogether.
shownof in
figureNobukawa
6a, andthat detailed
the X-rayemissionshapes, including soft thermal (Townsley et al. 2003; Hyodo H II region (Tsujimoto et al. 2007). Upon the confirmation ofly, we subtracted the background
spectrum
from
the
ring
a
thin
thermalplasmaorigin.
We
fitted
the
faint
ring
et al. 2008), hard thermal (Moffat et al. 2002; Ezoe et al. 2006), the previously claimed marginal diffuse detection in the Sgr DspecH II complex,
we plasmafurther aimmodel.
to construct
the X-rayspectrumabunrum, which is shown in figure and6a.nonthermal (Wolk et al. 2002; Law & Yusef-Zadeh
trum with2004;
an absorbed
CIE
The
elemental
Wang et al. 2006; Tsujimoto et al. 2007; Ezoe et al. 2006) emis- which gives important insights into the origin of the emission
e spectrum clearly shows the Si,
S, and Ar emission lines, dances of Si, S, and Ar were allowed to vary again. The bestsion. In addition to the X-ray emission, the measurement of the and the entire complex.
dition to a marginal emission line
to He-like
Ca. Wefit parametersconsistent
thosedetection
derivedfromX-raythe ring
X-ray dueabsorption
gives a constraint
on the distanceand hence are
Here,
we present witha significant
of diffuse
the physical scale of extended objects.
emission from the Sgr D H II complex with the Suzaku XIS.
the spectrum by an absorbed CIE
plasma
model
with
the
spectrumincludingtheG
359.77"0.09
andG
359.79"0.26
Several X-ray observations were reported in the Sgr D High signal-to-noise ratio spectra were obtained from two
ble abundances of Si, S, and Ar.
The
best-fit parameters
emission;
the X-rayfromplasmawithcharacteristhe temperregion.
In a BeppoSAX
study (Sidoli et al. 2001),
diffuse X-raydifferentemission
diffuse sources.
Wethe
discuss
their X-ray
emission
was significantly
detected from theSgr D of
SNRkT
and =tics0.96
and theirassociation
with sources
observedinour studykeV
isattenuatedwiththeabsorptionofe absorption column density andtheelectrontemperature
atureemarginally detected from the Sgr D H II complex. In an ASCA using
100-m Green Bank Telescope (GBT) and in other22"2
22 theand kTe study= 0.91keV.
Theelemental! 10archived
cm"2. We summarized
the best-fit
parameters(Sakanoet al.
2002),
the image wasN
plaguedby straymultiwavelength
data sets. Basedon these data,we
H = 5.5 ! 10 cm
H = 5.5
lightsorfroma nearby brightsource The
and was unsuitable
II complex. In
this paper,
proposea newview of the Sgrthe
D H physicaldances of Si, S, and Ar are solar
subsolarvalues.
in tableto search
2. Thisresultstrengthensconnectionoffor diffuse X-ray sources. In an XMM-Newton study (Sidoli we supplement the Suzaku data with those taken by XMMs are summarized in table 2. We
allofofpoint
thesources
best-werethe
faintbutring
to Gto359.77"0.09
and G
et al.note
2006),that
dozensidentified,no emission
Newton in order
evaluate the contributionof 359.79"0.26.
point sources
diffuse emission
was thedetectedpresumably due to high back- to the diffuse emission. Throughout this paper, we use east andrameters of the absorption column
density,electronground. The possible diffuse X-ray detection by BeppoSAX in west in the Galactic longitude direction, and north and south inerature, and the elemental abundancesareintermediate
4. andDiscussion
the Sgr D H II complex has not been confirmed
no spectral the Galactic latitude direction for simplicity.
information
existssubsection
for this source. 3.1)
s between those of G 359.77"0.09
(see
4.1.
359.77"0.09
2. Observations
We conducted X-ray observations of the Sgr
D H IIG
complex
G 359.79"0.26 (see table 3 of Moriet X-rayal. 2008).
using theImaging Spectrometer (XIS: Koyama et al.
2.1. Suzaku
onboard Suzaku(Mitsuda ettheal. 2007). The
The lowX-ray
back- spectrum of G 359.77"0.09 clearly shows therthermore, we made a ring2007a)spectrumexcluding
We used two XIS fields covering the Sgr D H II complex inground of XIS makes it particularly well-suited for finding
9.77"0.09 and G 359.79"0.26
tosurfaceexaminepresence
thermalplasma(kTe #1).0.7
the Suzaku
GC mapping
project(tableWe keV).
hereafterThecall theheavy
diffuseemission
sources of low
brightness andyielding of
theira thin
22 south"2fields (figure 1a). The north field
fieldsasnorthandsignal-to-noise
ratio spectra.
Indeed,absorptiona series of XISof Ntwo
her the region with the fainthighK˛-line
emission
from
=
6.9
!
10
cm
indicatesthattheplasma isH

高温プラズマ

1000年
0.9

1994$(ASCA)$

time variable 6.4 keV line

2000$(Chanrda)$ 2003$(XMM)$$$$$$$$$2005$(Suzaku)

M359.47–0.15

M359.43–0.07

13 New XRNe
0.8

1.0°

射手座B2

0.5°

0.7
M0.13–0.13
0.6
-0.5°

射手座A*
射手座B1 0.4

-1.0°

射手座C

300年

Neutral lines from light elements

0.3

M0.74–0.09
ke sulfur (referred as to faintring hereafter) is related located in the GC. Using the best-fit plasma parameters derived
ese two bright clumps. The excluded regions for from the G 359.77"0.09 spectral analysis, we can estimate
M0.74–sub 0.2as that
100光年
9.77"0.09 and G 359.79"0.26 are the same
some physical properties. Assuming that the distance to theibed in subsection 3.1 (see also the solid ellipse in plasma is 8.5 kpc, the emission measure is estimated to be 6.940
0.1 et al. ! 1058 cm"3 . If the plasma is an ellipsoid with dimensionse 1a) and that described in section 3 of Mori
Gas8), respectively. As is shownin figure 5b, the periphery of 4 0.9 ! 2 0.4 ! 2 0.4, corresponding to 12 pc ! 6.0 pc ! 6.0 pc
25NH
359.77"0.09 shows relatively bright K˛-line emission in the GC, the volume of the X-ray emitting plasma is 3.910highly ionized 22iron becauseof its location. Thus, in ! 1058 cm3 . The electron density of the plasma is then derived
-2)
(10
cm
to extract the corresponding background spectrum, we to be 1.3f "1=2 cm"3 , where f is a filling factor.
ved the areaRyu,TT+09
overlapped with the dashed rectangle shown
The elemental abundances of the plasma are consistent withure 1a from the background region. We again subtracted the solar values, which implies that the X-ray emitting plasma
ackground spectrum after applying the vignetting correc- has an interstellar medium (ISM) origin. The total mass of the

観測者
V
•

1=2

Thin Extended
6.4keV line
emissionMany AX J*** were discoveredby the ASCA Plane Survey,
which eventually results in
Suzaku’s good achievements.

This KP will make many
serendipitous discoveries,
which leads to fruitfulresults with Astro-H

Thank you.

23

Pointing Positions, Exposure Time and Feasibility• 10 x 100ksec• Stray lights from GX3+1

GX3+1

1.0

2.0

1.0

0.0

1.0

-2.0

-1.0

Counts s<1 keV<1
10<
0.01

0.1

Suzaku6-7 keV band image

Max. Stray Light(l=+2.5°)
2

Energy (keV)

5

10

10<

10<

Counts s<1 keV<1
10<
0.01

1

3.0

4.0

0.1

does not affect the Feline studies.

b (deg)1

Typical Stray Light(l=+3.5°)
2

Energy (keV)

5

10

24

Pointing Positions, Exposure Time and Feasibilityb (deg)
1.0

4.0

3.0

2.0

Suzaku6-7 keV band image

1.0

0.0

-1.0

1.0