1

銀河中心領域の高温プラズマの観測
高階電離鉄輝線の起源（100万年？の活動）
GC South/North プラズマ（10万年の活動）

鶴 剛 (Kyoto University)
on behalf of the Suzaku GC team.
20131114_ALMA_GC2013_v2.key

2

銀河中心領域の拡散Ｘ線の概観

Observation of the GC region with Suzaku

1deg

3

R: 0.5-2.0keV
G: 2.0-5.0keV
B: 5.0-8.0keV

Suzaku is the best observatory to observe“diffuse” emission from the Galactic center region.
High Spectral Resolution,
Large Collecting Area,
Low and Stable Non-X-ray Background204pointings, 5.96Msec
SWG, AO, LP, KP x2 (|l|<3.5°, |b|<5°)

36 refereed papers,
7 Doctor Theses.

4

0.1

He-like S Kα
(2.45-keV line)

Neutral Fe Kα(6.4-keV line)

1deg

Narrow Line

0.01

−1

Counts s keV−1

1

Suzaku Spectrum of the GC region

Mapping1

He-like Fe Kα(6.7-keV line)

2

5
Energy (keV)106.7-keV Line Image (He-like Fe Kα)56.7keV (Continuum subtracted)

CHAPTER 2. REVIEWSgr A*

Photons cm-2 s-1 arcmin

-2

10
10

(a)
-5

•
6.7-keVFe XXV K

-6

10

-8

10

-9

•

GC

10-7

GR

r〜500ly-

F=10×exp(–l/0.6deg) + exp(–l/50deg)

0.01

0.1

1

10

S XV K(b)
ThermalPlasmas10-5
smoothly
distribute in-6
10
the GC region.
-7
10
The origin is still under
debate.
-810
Truly
diffuse plasma-910filling in the GC region.
Or, collectionof faint 1
0.01
0.1
*
unresolved
point
Distancefrom Sgr A along thsources.

Photons cm-2 s-1 arcmin-2

100ly

100

*

Distance from Sgralong
theSgrlongitude
l* A
(deg,
from
A*) |l* | (degree)

Uchiyama+11, +12-

6

6.4-keV Line Image (Neutral Fe Kα)

FeI 6.4 keV Map by Suzaku- 0.0ºSgr B2
M0.74–0.09

Sgr B10.5º

1.0º

Sgr A*

b

Sgr C

0º

-0.5º

Sgr A*

Sgr C

l

-0.9º

CS ( J=1–0) Map by Tsuboi+1999

Sgr B
b
300 pc of the Central Molecular Zonel

• 6.4-keV line generally traces the distribution of the molecular clouds.
• 6.4-keV fluorescence line is emitted from MC.
What is the ionizing particles ? Electrons or X-rays ?

7
6.7keV (Continuum subtracted)

Sgr A*
100ly

2.45keV (Continuum not subtracted)

Sgr A*
100ly

6.4keV (Continuum
2.45keV(Continuumsubtracted)
not subtracted)

100ly
100ly

Sgr A*A*
Sgr

G1.2-0.0(Sawada09+)
S210

G0.42−0.04(Nobukawa+08)
M. Sawada et al.

G359.41−0.12(Tsuru+09)G359.79-0.26(Mori+08)

G0.61+0.01(Koyama+07)

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.

Super Bubble

H. Mori et al.

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

Sgr A*

G359.12-0.05(Nakashima+10)G359.77-0.09(Mori+09)[Vol. 61,

“Chimney”

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.

the Chimney

0.00

0.0

b

2. Observations
2.1. Suzaku-0.2

G359.41-0.12

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

Tsuru+09
359.6

Mori+09
0

0.05

0.1

0.15

0.2

359.4
0.25

0.3

359.2

l
0.35

Tornado[Vol. 61,

0.4

0.45

0.5

0.55

Galactic latitude (degree)92

1. Discovery of SNR candidates

−0.05
−0.10
−0.15
−0.20
−0.25

Sawada+11
Galactic longitude (degree)

357.85 357.80 357.75 357.70 357.65 357.60

89

高階電離鉄輝線の起源：100万年？の活動〜点源寄せ集め or 真に拡がる？〜
Uchiyama et al. (2011) PASJ 63, S903
Uchiyama FY2009 Doctor Thesis, Kyoto Univ.

3. Fe-K Lines (6.7, 6.9 keV) Distributions
Image

10

Truly Diffuse orPoint Sources ?

Divided into small
areas and made
spectra, fit theindividual spectrumwith a power-law+ Gaussians.
Fluxes (F)F6.7 : 6.7 keV line
F6.9 : 6.95 keV lineSurface brightness(10-6 ph/s/cm2/arcmin2)

11
B：EastR：West• The border between

GC and GR is locatedat l = 1〜2deg.

Ridge: Yamauchi
GC: Nobukawa+• The temperature of GC
would be higher thanGR.

Nobukawa, Hyodo+,
Yamauchi+09

GlobalDistribution
of Fe ofKαFeLines
in theinGalactic
CenterRegionGlobalDistribution
Kα Lines
the Galactic
CenterRegion(b)
6.7keV Line Profile vs (b)Stellar
Mass Distribution
This workThis work
Koyama+07
Koyama+07
Yamauchi+09
Yamauchi+09

x4 〜 x 10 (at b*=0.0)

6.7keV

10-6

10-7

10-5

-8

10-8
0.01
0.1
1
10
0.01
0.1
1
10
*
Distance from
Sgr from
A* alongthelongitude|l*| (degree)
Distance
Sgr A
along
the longitude|l*| (degree)

-6

-7

-8

Observed photons cm-s s-1 arcmin-2-5

Nuclear10-5
stellarcluster
10-6

(d)

10-7

Nuclear bulge

-8

10

10-6

10-7

10-8

(d)

A new population of
10
point sources with astrong 6.7keV line.
10orTruly diffuse
10plasma

10-6

6.7keV Lines Origin of 6.7keV
10
10
Excess atline in GC is
GC
different from GR-7(at l =-0.114)*

10-8

Nuclear Galactic Galactic 10-5This workThis work
bulge
disk
stellar Koyama+07
Koyama+07
Yamauchi+09
disk Yamauchi+09
Observed photons cm-s s-1 arcmin-2

)

10-6

10-5
Observed photons cm-s s-1 arcmin-2-7

Observed photons cm-s s-1 arcmin-2

-6

10-5

-7

-8

10

0.1
1
0.1
1
*
Distance from
Sgr from
A* along
thelatitudeDistance
Sgr A
along
the|blatitude|b*| (degree)*| (degree)-5

Observed photons cm-s s-1 arcmin-2-5

Observed photons cm-s s-1 arcmin-2

a)

12

-6

-7

Uchiyama+11
10
-8

13

The 6.7 keV line flux vsIntegrated point source flux
(Chandra deep exposure)
Near GC ( < 0.3 deg)
Nobukawa, Hyodo+l-distribution
Sgr A*

b-distribution
Sgr A*

10 x 6.7 keV line (EW=0.5 keV)Distribution of Point source flux (4.8-8 keV)The 6.7keV has more extended
distribution than point sources.

( ｂ)

14

Plasma Parameters in the Sgr A (assuming ZFe=1.2)• Size ~ 50pc x 30pc
~0.70°• L ~ 2×10 ergs/s ~0.36°• n ~ 0.1cm• n ~ 0.4cm• E ~ 3×10 ergs R: 6.7keV, G:2.45keV, B: 6.4keV• Escape Time scale (latutude) τ = Size/Cs = 2×10 yr• Heating Rate = E /τ ~ 5×10 ergs/s ~ 10 SN yr• Much higher than the current activity of Sgr A and

Tsuru+ (Suzaku2007)

2-10
ave

36

-3

-3

peak
gas

52

4

esc

gas

esc

40

-3

-1

*

~10-5 SN yr-1 expected from the stellar mass in thisregion.
Plasma is in the ionization equilibrium or not ?

EI or NEI

6.7keV Center Energy

6.65

Tsuru+ (Suzaku2007)

8

10

6.55
6.5

11
1012
1010
Normalizatino
Ratio 10
6.9/6.7keV
kT=6.5keV
nt [sec/cm3]

0.33±0.02

0.1

0.2

kTe=6.5keV
13
10
VNEI

Line ratio
6.9/6.7-keV

0.05
0.01

Koyama, Hyodo
et al. (2007)6

6.7-keV Line
CenterkTe=6.5keV

0.02nτion > 2×1012 sec cm-3>> nτesc ~ 1×1011 sec cm-3
small escape (age > 6e+5yr)
Normalizatino Ratio 6.9/6.7keV••

6680 +3,-6eV

6.6• Suzaku spectrum

15

kT=6.5keV

1010

10
10

1011

11
10

1012
nt [sec/cm3]

12
10

1013

13
10
nt (sec cm-3)

1014

14
10

Confinement by Magnetic Field ?

16

Tsuru+ (Suzaku2007)• Pressure• B = 0.1mG~1mG• P /k =10 -10 K/cm ~ P /k =2×10 K/cm

(eg.Yamauchi+90, Koyama+96, Muno+04)

B

6

8

3

gas

7

3

• The strength of the magnetic field can confine 6.7keV plasma.
• Slow diffusion → Makes the required heating rate lower.
• But, the orientation of the mag. is vertical against the disk.
→ Easy to escape.

2007.12頃こんなことを考えていた...
→西山さん，長田さんに相談%$

**"*. 17

Ks polarization map 32 (P/P  2)UPU[S-

0.5%

VP
WUS-
Nishiyama+13, ApJL, 769, 28

with the scale height of the 6.7 keV emission, 0. 27(Uchiyama60et al. 2013).
18

Fig. 5.— Polarimetry results covering 3.◦ 0 × 2.◦ 0in the Galactic coordinate, together with an intensity map of 6.7 keV line emission (Nobukawa et al.
2012). The cyan vectors show the inferred magnetic field direction, and the lengths are proportional to polarization percentage. The vectors areaveraged in a circle of 2." 4 radius with a 3." 0 grid,and plotted with thick bars (detected with morethan 3σ) and thin bars (detected with◦ 2 − 3σ).
Fig. 5.— Polarimetry results covering 3. 0 × 2.◦ 0n the Galactic coordinate, together with an intenThe obtained polarization map (Fig. 5) sugsity map of 6.7 keV line emission (Nobukawa et al.
gests a large-scale toroidal MF configuration in the2012). The cyan vectors show the inferred magNB. The histogram (Fig. 6) of the MF directions
netic field direction,and the lengths are proporat | b |< 0.◦ 4 has a clear peak at 90◦ which is the

Position Angle [degree]

Number ofment does not work well, although observations
the Galactic plane has been claimed in the GC
of the MF in the NB have been limited to the(Nishiyama et al. 2010).
region in dense molecular clouds (Novak et al.
2000, 2003; Chuss et al. 2003) and very thin,
non-thermal radio filaments (Tsuboi et al. 1986;
Yusef-Zadeh et al. 1997; Lang et al. 1999). Recent
observations have revealed that NIR and widefield polarimetry offers a promising tool to tracea large-scale MF, and a troidal configuration near
the Galactic plane has been claimed in the GC(Nishiyama et al. 2010).

120

Number of Fields

100

80

40

20

all
o
|b|< 0.4o| b | > 0.4

0
0

20

40

60

80

100

120

140

160

180

Position Angle [degree]
60

Fig. 6.— Histograms of the magnetic field direction40at | b |≤ 0.◦ 4 (red), | b |> 0.◦ 4 (blue), and both(black). The red histogram has a clear peak at20
the direction
almost parallel to the Galactic plane(90◦ ), while the blue one has a peak at ∼ 150◦ ,0 perpendicular to the plane.
almost020
40
60
80 100 120 140 160 180

The determination of the MF strength is stillquite difficult in this region, but it seems to
Fig.converge
6.— Histogramsof theofmagnetic
field
directo◦ the value
50
"
B
[µ
G]
" 200
◦
tion(e.g.,
at | b Ferrière|≤ 0. 4 (red),|> 0. 4 (blue),both At
2011;| b Crocker
et al. and2011).
(black).
The strength,
red histogram
has a clear
peakdensity
atthis field
the magnetic
energythe (∼
direction
almostparallelto theGalactic
plane
−3
0.1
−
1
keV
cm
)
reachesnearlyequipartition◦(90◦with), while
the
blue
one
has
a
peak
at
∼
150
those of diffuse hot plasma (∼ 0.5 keV cm,−3 )almostthe plane.
and perpendicular
gas turbulenceto(seeFig. 4 in Crocker et al.
2010). This suggests that MFs provide significant
The determination of the MF strength is stillpressure support against the diffusion of the hotquite difficult in this region, but it seems toplasma.
converge to the value of 50 " B [µ G] " 200
the plasma
not etsupported,
it At
would
(e.g., If
Ferrière2011; were
Crockeral.
2011).
Nishiyama+13,
ApJL,
769,
28

磁場は銀河面に平行→閉じ込められる可能性あり

19

GC South Plasma : 10万年前の活動〜再結合プラズマの発見〜
Nakashima et al. 2013, ApJ, 773, 20
To be a part of Nakashima FY2013 Doctor Thesis, Kyoto Univ.

Bipolar X-ray emission
from the GC
1.0 1-3 keVのX線
中性鉄輝線
5-8 keVのX線

銀緯 (度)Sgr A*

0.0

X線反射星雲1E 1740.7-2942(deg.)
Galactic
Galactic latitudelatitude (degree)

GC north

GCDX

200pc

Chandra (1-3 keV)
Suzaku (1-3 keV)

1.0
1.0

0.5

-0.5

20

0.0
0.0

GC North
Galactic plane

Sgr A*GC South

-1.0
-1.0

-1.0

Ｘ線吸収=銀河中心までのKsバンドの吸収
GCのプラズマGC south
-1.5
1.0

•
•

M = 710M@, E = 1.6x1051ergs, n=0.16cm-3
0.5
0.0
-0.5
-1.0
0.5
0.0
エネルギーは10~100個のSNR．星団は無い．
-0.5
銀経 (度)
0.5
0.0
-0.5

Galactic longitude
Galactic
longitude(degree)(deg.)

単一のSNR，Super Bubbleではない．

Recombining plasma
model
Recombining
PlasmaMissing Fe L-shell complex

(a)

−1
χ
Counts s−1 keVCountss−1 keV−1

100

10−2
10−1
(b)

χ

BGD

• 再結合連続線 RRCは，CIE
では極めて弱い．

Fe-L

Fe-L

(c)
(b)

χ2/d.o.f = 1378/350
2617/352

Fe-L

Si XIV Si-RRC

599/348
χ2/d.o.f = 1378/350

Si XIV Si-RRC

(d)

1

2
Energy (keV)• イオン化非平衡
kTZ > kTe
で再現成功

S-RRC

(d)
(c)

0
−5 イオン化非平衡モデル

0−5χ2/d.o.f = 2617/352

GC south0−5 イオン化平衡モデル

5ではフィットできず．

多温度CIEの可能性あり

0
−2
10
−5

5

• 1成分イオン化平衡(1CIE)• H-Si-Kαが強いだけ

Fe-L

χ

Background
Recombining plasma model
Missing Fe L-shell complex
Background

10−1
100

5
χ

– 15 –

(a)

5

21

S-RRC

5 χ2/d.o.f = 599/34810

Fig. 4.— (a) Spectrum extracted from the entire source region. Only the co-added FI spectra

22

Recombining Plasma
Ionizing plasma v.s. Recombining plasma
kT

NEI

CIE

kTinitRecombining
過電離
kTe

kTinit = 0

Ionizing
未電離 = 衝突電離中
13 s cm-3~10
SNRの「標準」プラズマ
Time Scale (nt)23

Recombining Plasma
Ionizing plasma v.s. Recombining plasmakT

1.63 keV

kTinitkTz

kTe

0.46 keVNEI

CIE

GC South

5.3 x 1011 s cm-3

~1013 s cm-3
Time Scale (nt)τRP = 1.1x105yr << τcool ~ 1-2x109yr

How to make Recombining Plasma
Ionizing plasma v.s. Recombining plasmakT

種1.63 keV

kTinitkTz

kTe

0.46 keVNEI

CIE

GC South

5.3 x 1011 s cm-3
Time Scale (nt)~1013 s cm-3

τRP = 1.1x105yr << τcool ~ 1-2x109yr

24

How to make Recombining Plasma
Ionizing plasma v.s. Recombining plasmakT

1.63 keV

kTinitkTz

kTe種

0.46 keVNEI

CIE

GC South

5.3 x 1011 s cm-3
Time Scale (nt)~1013 s cm-3

τRP = 1.1x105yr << τcool ~ 1-2x109yr

25

How to make Recombining Plasma• 電子温度を下げる．
• 断熱膨張により急激にkTeが下がった．その後ゆっくり再結合• 初期状態 kTinit = kTz = kTe = 1.63keV• T V , kTe=1.63→0.46keV(1-γ)

体積が6倍に膨張（サイズ1.8倍）密度は 1cm-3 → 0.16cm-3．

•(97 /1.8)kpc → 97kpc へ音速で膨張に必要な時間 ~ 8x104yr• イオン化温度を上げる．
• σ(光電効果) z^5 Ｘ線照射で重元素を選択的に電離• 初期状態 kTinit = kTz = kTe = 0.46keV• Sgr A*からのＸ線．L ~ 7.6x10 ergs/s• GC Plasma には，光電離 (RP)の痕跡がない． ビーミング
X

43

26

27

Plasma Origin• 種プラズマの作り方• Starburst Activityに伴う銀河風• v=510km/s (Cs @ kTe=1.6keV) GCから4x10 yr• 10 -10 yr前にStarburst Activity (Matsunaga+11,Yusef-Zadeh+09)
557• Sgr A*からの(何らかの)エネルギー注入で冷たいガスが電離• 600~50yr前の活動 L ~1x10 ergs/s• If これが ~10 yr続いたと仮定 L ~10 ergs ~ E(GC south)
X

5

39

X

51

28

GC South North〜南があるなら北にも？〜Proposing as a key-project of Suzaku AO9
To be a part of Nakashima FY2013 Doctor Thesis, Kyoto Univ.

29

How about GC North ?
2.0(a) Suzaku 1-3 keV(b) Chandra 1-4 keV(c) ASCA 1-3 keV

1.5

GC Nouth

Galactic Latitude (degree)

1.0

0.5

Sgr A*

0.0

Sgr A*Sgr A*-0.5-1.0

GC South
GC South

-1.5

-2.0

0.5

0.0

359.5

0.5

0.0

359.5

Galactic Longitude (degree)

0.5

0.0

359.5

30

Tip of DHN

ASCA 1-3keV
Radio lobe
Molecular
Cloud

Hα
1.0

DHN
0.5

0.0

X-ray
loop?
S-shape
0.5

0.9

0.0

359.5

Galactic Longitude (degree)

359.0

Galactic Latitude (degree)

Galactic Latitude (degree)

1.5

ASCA 3-6keV (Contour)
Color = Spitzer 22 µm, Contour = ASCA 3-6 keV

0.8

0.7

• Sgr A*の活動?
• ジェット or アウトフロー?
• NSCからの磁気タワー?
• 銀河面の高温プラズマの巻き上げ?

DHN

Hard
X-ray
Interaction?

0.6

0.2

0.1

0.0

359.9

Galactic Longitude (degree)

Fe-K line (6.4keV ?) from MC interacting Radio Lobe

ASCA 1-3keV
Galactic Latitude (degree)

1.5

Radio lobe
Molecular
Cloud

Hα
1.0

DHN
0.5

0.0

X-ray
loop?
S-shape
0.5

0.0

359.5

359.0

Galactic Longitude (degree)• New XRN ?
• 従来 |b|<0.1度(15pc)• 初めての高銀緯(b=0.1-0.5°)• Cosmic Rays (Electron orProton) from Radio Lobe ?

31Summary32• 高階電離鉄輝線の起源は，暗く鉄輝線の強い未知のX線天体種族．本質的に拡がったプラズマ．

• 本質的に拡がったプラズマの場合，磁場閉じ込め可能性あり．
• GCの南200pc (GC South)および北 (GC North)の領域に SNRの10~100
個分のエネルギーを持つプラズマを発見した．

•• GC Northは様々な構造を持つ．

GC Southは~105yr前に過電離状態になった再結合プラズマ．

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Thank you.