Origin of the 6.4-keV line of the Galactic Ridge X-ray Emission (GRXE) ~ The First Report ~

Origin of the 6.4-keV line of the

Galactic Ridge X-ray Emission (GRXE)

~ The First Report ~

20140219_GC_EastRidge_Suzaku-MAXI2014_v11.key

T.G.Tsuru (Kyoto), H.Uchiyama (Shizuoka), K.K.Nobukawa, M.Nobukawa, S.Nakashima, K.Koyama (Kyoto),

K.Torii, Y.Fukui (Nagoya Univ.)

0 106 213 320 426 534 640 746 853 960 1066 0.000

2.000 359.000 357.000

-2.000-1.0000.0001.00

6.4-keV line emission from Ridge

²

Sgr D B A C E

Ridge Suzaku found that 6.4-keV line emission

with nearly equal EW uniformly exist.

Key Question.

What is the origin of this 6.4-keV line emission in the Galactic ridge ?

EW map of the 6.4-keV line near GC

extends toward the Galactic ridge.

No region with such high EW has been discovered except the GC.

3

6.4-keV line flux

Asymmetric Distribution of 6.4-keV line

Intensity (K km/s )

102

103

Galactic longitude l (deg)1 0 -1 -2 -3 -4 2

3 4

co12_l_356-4_at_b-0.4pm0.45.txt

)

2

/arcmin

2

Intensity (1e-7 photons /s /cm

_-1

10 1 10

Galactic Longitude l (deg)1 0 -1 -2 -3 -4 2

3 4

FeI (6.4 keV) l profile @ b=-0.046 pm 0.05 deg

Ridge

GC East (left) Ridge

GC West (right)

GC XRN

?

KP

Pointing Positions

⁴

• l = +2.0 ~ +4.0, 100ksec x 10 points

• 7 pointings done Today’s talk.

• Remaining 3 pointings will be done in this spring.

0.0 1.0

2.0 3.0

4.0 1.0 -2.0 -3.0 -4.0

-1.0 -1.0

l (deg) b (deg)

Suzaku

6-7 keV band image

GX3+1

GC East (GC left) GC West (GC right)

0.00e+00 4.97e-07 1.99e-06 4.50e-06 7.99e-06 1.25e-05 1.80e-05 2.45e-05 3.20e-05 4.05e-05 5.00e-05

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

1-2 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

2-3 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

3-4 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

4-5 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

7-8 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

5-6 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

507075010

507069010 507072010

507071010 507070010

507073010

EXPOSURE MAP

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

6-7 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

0.5-1 keV

0.00e+00 4.97e-07 1.99e-06 4.50e-06 7.99e-06 1.25e-05 1.80e-05 2.45e-05 3.20e-05 4.05e-05 5.00e-05

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

1-2 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

2-3 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

3-4 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

4-5 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

7-8 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

5-6 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

507075010

507069010 507072010

507071010 507070010

507073010

EXPOSURE MAP

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

6-7 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

0.5-1 keV

0.00e+00 4.97e-07 1.99e-06 4.50e-06 7.99e-06 1.25e-05 1.80e-05 2.45e-05 3.20e-05 4.05e-05 5.00e-05

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

1-2 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

2-3 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

3-4 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

4-5 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

7-8 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

5-6 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

507075010

507069010 507072010

507071010 507070010

507073010

EXPOSURE MAP

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

6-7 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

0.5-1 keV

0.00e+00 4.97e-07 1.99e-06 4.50e-06 7.99e-06 1.25e-05 1.80e-05 2.45e-05 3.20e-05 4.05e-05 5.00e-05

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

1-2 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

2-3 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

3-4 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

4-5 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

7-8 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

5-6 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

507075010

507069010 507072010

507071010 507070010

507073010

EXPOSURE MAP

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

6-7 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

0.5-1 keV

0.00e+00 4.97e-07 1.99e-06 4.50e-06 7.99e-06 1.25e-05 1.80e-05 2.45e-05 3.20e-05 4.05e-05 5.00e-05

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

1-2 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

2-3 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

3-4 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

4-5 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

7-8 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

5-6 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

507075010

507069010 507072010

507071010 507070010

507073010

EXPOSURE MAP

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

6-7 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

0.5-1 keV

Observation - Images

5

0.00e+00 4.97e-07 1.99e-06 4.50e-06 7.99e-06 1.25e-05 1.80e-05 2.45e-05 3.20e-05 4.05e-05 5.00e-05

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

1-2 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

2-3 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

3-4 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

4-5 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

7-8 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

5-6 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

507075010

507069010 507072010

507071010

507070010

507073010

EXPOSURE MAP

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

6-7 keV

3.500 3.000 2.500 2.000 1.500 1.000

0.500

0.000

0.5-1 keV

6

Observation - Stray Light from GX3+1

• Stray light from GX3+1, a very bright LMXB.

   Careful analyses are necessary.

GX3+1

Three regions of Stray Light from GX3+1

7

0 0.0055 0.016 0.039 0.082 0.17 0.34 0.69 1.4 2.8 5.5

3.400 3.300 3.200 3.100 3.000 2.900

0.4000.3000.2000.1000.000-0.100

Galactic longitude

Galactic latitude

507074010 XIS3 (l b)=(3.14997262373267 0.153947305958329)

•   Quadrant Boundary 領域を含む3 つの視野について、NXBを引き抽 出領域の大きさを補正したスペク

トルを、Backside Only 迷光領域、

Quadrant Boundary領域 それぞ れについて作成し比較 (スペクトル 抽出領域は添付資料 : Region.pdf  を参照)。  

4.  BS Only 迷光領域・QB領域の

スペクトル比較  ^点源あり 

0 0.0086 0.026 0.06 0.13 0.27 0.54 1.1 2.2 4.3 8.7

2.300 2.200 2.100 2.000 1.900 1.800 1.700

0.2000.1000.000-0.100-0.200-0.300

Galactic longitude

Galactic latitude

507069010 XIS3 (l b)=(1.99999795923447 -0.0459668951455564)

GX 3+1を 中心とし、

視野中心を 通る円弧 

2―5 keV 

上記より半径 が2 arcmin 大きな円弧 

QB領域 

BS  Only領域 

0 0.0073 0.022 0.051 0.11 0.23 0.46 0.92 1.9 3.7 7.4

3.500 3.400 3.300 3.200 3.100 3.000

0.7000.6000.5000.4000.3000.200

Galactic longitude

Galactic latitude

507075010 XIS3 (l b)=(3.25006212440054 0.403986429722952)

•

Backside Reflection Region

•

Scattered at the backside of the primary reflector.

•

Followed by normal reflection.

•

Less Bright

•

Important at < 1.5 keV

•

Secondary Reflection Region

•

Reflected only once by the secondary reflector.

•

Brightest, Comb-like Structure

•

Quadrant Boundary Region

•

Shadow of the Structure of Quadrant.

•

Free from Stray Light

Contiuum Component : QB + BS

• 

QS Only 領域とQB領域でスペクト ルは、ほぼ一致 (50704010除く)。

(XIS 0以外のセンサーについては 添付資料 Spectra.pdf を参照。） 

4.  BS Only 迷光領域・QB領域のスペクトル比較 

10

−1−1 normalized counts s keV −6−5−4 101010 5

Energy (keV)

[Black]:Back Side Only Region [Red]:Quadrant Boundary Region 507069010 XIS0 Back Side vs Quadrant Boundary

10

−1−1 normalized counts s keV −6−5−4101010 5

Energy (keV)

[Black]:Back Side Only Region [Red]:Quadrant Boundary Region 507074010 XIS0 Back Side vs Quadrant Boundary

10

−1−1 normalized counts s keV −6−5−4 101010 5

Energy (keV)

[Black]:Back Side Only Region [Red]:Quadrant Boundary Region 507075010 XIS0 Back Side vs Quadrant Boundary

BS Only迷光領域 

QB領域 

Counts/s/keV/arcmin2 

QB領域に 点源あり 

Counts/s/keV/arcmin2  Counts/s/keV/arcmin2 

Red : Quadrant Boundary region

Black : Backside region

Comparison between QB and BS

•

Backside Stray light from GX3+1 < 5.4% above 5keV

•

Backside = Quadrant Boundary (stray light free)

Continuum Component - obtained from QB + BS

8

Continuum Component above 5 keV : data from QB + BS region.

Maximum Allowed Stray Light Spectrum

Observed Spectrum

Backside Reflection Region

5.4%

輝線強度分布 

• 

自分の解析の検証の為に、河畠さんの結果と比較。 

– 

b依存性を補正。 

– 

河畠さんのデータは吸収を補正した値のようなので、N

_H

=5 10

²²

/cm

² 

の吸 収を受けた値に修正。 

10^-8 10^-7 10^-6

1.8 2

2.2 2.4

2.6 2.8

3 3.2

3.4 Observed Intensity (photon/s/cm2 /arcmin2 )

Galactic longitude (degree) Fe XXV K Profile

Uchiyama Kawabata

10^-8 10^-7 10^-6

1.8 2

2.2 2.4

2.6 2.8

3 3.2

3.4 Observed Intensity (photon/s/cm2 /arcmin2 )

Galactic longitude (degree) Fe I K Profile

Uchiyama Kawabata QB+BS

Whole FOV

QB+BS Whole FOV

Quadrant Boundary + Backside Reflection

whole FOV

6.7-keV line flux 6.4-keV line flux

Fe-K line flux - obtained from the whole FOV

• GX3+1 : No narrow Fe-K line is reported by XMM-Newton.

would be able to use the whole FOV.

9

20140203_GC_East_Uchiyama3.pdf

Fe-K lines : from the whole FOV for good statistics

• No significant difference between “QB+BS” and “the whole FOV”.

6.4-keV 6.7-keV lines vs l

10

4 2 0 2 4

108 107 106 105ph s1 cm2 arcmin2

Galactic Longtitude (degree) red: 6.4 keV green: 6.7 keV

GC East GC West

GC

6.7-keV

6.4-keV This Key

Project

6.4-keV 6.7-keV lines vs l

11

6.4-keV 6.7-keV

GC East GC West

4 2 0 2 4

10

8

10

7

10

6

10

5

ph s

1

cm

2

arcmin

2

Galactic Longtitude (degree) red: 6.4 keV green: 6.7 keV

4 2 0 2 4

10

8

10

7

10

6

10

5

ph s

1

cm

2

arcmin

2

Galactic Longtitude (degree) red: 6.4 keV green: 6.7 keV

4 2 0 2 4

10

8

10

7

10

6

10

5

ph s

1

cm

2

arcmin

2

Galactic Longtitude (degree) red: 6.4 keV green: 6.7 keV

4 2 0 −2 −4

10

⁻⁸

10

⁻⁷

10

⁻⁶

10

⁻⁵

Fe I α (ph s

−1

cm

−2

ar cm in

−2

)

Galactic Longtitude (degree)

FeXXVKa−FeIKa_Int_OnGalplane_kumiko_2.qdp NANTEN_13CO_l_m4−p4_b_m0126_p0034_l.dat

10 10

²

10

³

10

⁴

CO Intensity (K km s )

13−1

Origins of 6.4-keV and 6.7-keV are different.

6.7-keV : Symmetry 6.4-keV : Asymmetry

0 50 100 150 200 250 300 350 400

355.

356.000 356.500

357.000 357.500

358.000 358.500

359.000 359.500

0.000 0.500

1.000 1.500

2.000 2.500

3.000 3.500

4.000 4.500

-0.5000.0000.500

Molecular Clouds

12

SgrD B A C E GC West (Right)

GC East (Left)

Takeuchi+10

13CO, NANTEN

0 50 100 150 200 250 300 350 400

355.

356.000 356.500

357.000 357.500

358.000 358.500

359.000 359.500

0.000 0.500

1.000 1.500

2.000 2.500

3.000 3.500

4.000 4.500

-0.5000.0000.500

Molecular Clouds

12

0 50 100 150 200 250 300 350 400

355. 356.000

356.500 357.000

357.500 358.000

358.500 359.000

359.500 0.000

0.500 1.000

1.500 2.000

2.500 3.000

3.500 4.000

4.500

-0.5000.0000.500

Clump2

footpoint

SgrD B A C E GC West (Right)

GC East (Left)

Takeuchi+10

13CO, NANTEN

6.4-keV line flux & 13CO vs l

13

4 2 0 −2 −4

10

⁻⁸

10

⁻⁷

10

⁻⁶

10

⁻⁵

Fe I α (ph s

−1

cm

−2

ar cm in

−2

)

Galactic Longtitude (degree)

FeXXVKa−FeIKa_Int_OnGalplane_kumiko_2.qdp NANTEN_13CO_l_m4−p4_b_m0126_p0034_l.dat

10 10

²

10

³

10

⁴

CO Intensity (K km s )

13−1

4 2 0 −2 −4

10

⁻⁸

10

⁻⁷

10

⁻⁶

10

⁻⁵

Fe I α (ph s

−1

cm

−2

ar cm in

−2

)

Galactic Longtitude (degree)

FeXXVKa−FeIKa_Int_OnGalplane_kumiko_2.qdp NANTEN_13CO_l_m4−p4_b_m0126_p0034_l.dat

10 10

²

10

³

10

⁴

CO Intensity (K km s )

13−1

4 2 0 −2 −4

10

⁻⁸

10

⁻⁷

10

⁻⁶

10

⁻⁵

Fe I α (ph s

−1

cm

−2

ar cm in

−2

)

Galactic Longtitude (degree)

FeXXVKa−FeIKa_Int_OnGalplane_kumiko_2.qdp NANTEN_13CO_l_m4−p4_b_m0126_p0034_l.dat

10 10

²

10

³

10

⁴

CO Intensity (K km s )

13−1

4 2 0 −2 −4

10

⁻⁸

10

⁻⁷

10

⁻⁶

10

⁻⁵

Fe I α (ph s

−1

cm

−2

ar cm in

−2

)

Galactic Longtitude (degree)

FeXXVKa−FeIKa_Int_OnGalplane_kumiko_2.qdp NANTEN_13CO_l_m4−p4_b_m0126_p0034_l.dat

10 10

²

10

³

10

⁴

CO Intensity (K km s )

13−1

4 2 0 −2 −4

10

⁻⁸

10

⁻⁷

10

⁻⁶

10

⁻⁵

Fe I α (ph s

−1

cm

−2

ar cm in

−2

)

Galactic Longtitude (degree)

FeXXVKa−FeIKa_Int_OnGalplane_kumiko_2.qdp NANTEN_13CO_l_m4−p4_b_m0126_p0034_l.dat

10 10

²

10

³

10

⁴

CO Intensity (K km s )

13−1

footpoint

6.4-keV

13CO

GC West GC East

6.4-keV line follows CO.

6.4-keV line flux vs 13CO

14

10 100

108 107

Fe I (ph s1 cm2 arcmin2 )

13CO Intensity (K km s ¹)

FeIKa_OnGalPlane_13CO_l_m4 p4_b_m0126_p0034_l_v2_l=1.65 4.0.q

GC East (left)

GC West (right)

6.4- keV

13CO

6.4-keV line : Diffuse Origin

Fluorescence from Cool Matter.

10^-9 10^-8 10^-7 10^-6

0.1 1 10 100

GRXE Fe I K Line Intensity (ph/cm2 /arcmin2 /s)

N_H by HI (LAB) + H₂ (Dame) (10²²/cm²)

|l|>2D or |b|>1D

Uchiyama+14 (in prep.)

10 100

108107

Fe I (ph s1 cm2 arcmin2)

13CO Intensity (K km s ¹)

FeIKa_OnGalPlane_13CO_l_m4 p4_b_m0126_p0034_l_v2_l=1.65 4.0.q

l = 1.5~2 and >2 :

Same Correlation 6.4-keV has the Same Diffuse Origin in the whole Galactic Disk.

15

6.4-keV vs 13CO in the Whole Galactic Disk

Ionizing particles

•

6.4-keV line flux ~1e-7 ph/cm2/sec/arcmin2 and NH ~1e+23cm-2 are observed in GC East and West. 

•

XRN (X-ray Reflection Nebula)

•

Already seen in the GC.

•

Sgr A* Lx(Sgr A*) ~10^41 ergs/s in the GC East and West regions.

•

Much higher Lx is required for Sgr A* in order to explain the whole disk. 

•

LECRp (Low Energy Cosmic Ray Proton)

•

Up ~ 1400 eV/cm3 (cf. Dogiel+11, Ip+85) 240μG (equipartition)

•

Might be OK in the GC and near GC.

•

Too high in the Galactic disk.  

•

LECRe (Low Energy Cosmic Ray Electron)

•

Ue~1 eV/cm3 (cf. Valinia+00)

16

Key to solve Spectrum

From Observational Point of View,

Still Open Question

Thank you.