1. Galactic Center Diffuse X-rays with Suzaku
Katsuji Koyama, Kyoto University
Posters : ,
Origin of 6.7/6.9 keV Lines
: Collisional Excitation or Charge Exchange
: Diffuse or Point Sources
(2) Discoveries of New SNR Candidates
(3) Origin of 6.4 keV Line
: X-Ray Reflection or Electron Bremsstrahｌung
: Time Variability of the 6.4 keV clumps.

2. 3-Color Image Red: 6.7 keV Blue: 6.4 keV Green: 2.45 keV Energy 6 7 8
Fe24+Kα
Fe25+Kα
Fe24+Kβ
Fe Kα
Ni26+Kα
Fe24+ Kβ
Fe25+Kβ
Ni27+Kα
Ni Kα
Si12+Kα
Si12+Kβ
Ar16+Kβ
Ar16+Kα
Si13+Kα
Ca18+Kα
Ca19+Kα
Ar17+Kα
S14+Kα
S15+Kα
S14+Kβ
Energy
3-Color Image
Red: 6.7 keV
Blue: 6.4 keV
Green: keV

3. Charge Exchange or Collisional Excitation ?
H-like Observed (eV) Lab δ (eV)
S Lya (+4-3)
Fe Lya (+3-2)
Mn Ka (+2-1)
Energy Scale Check
Using the H-like Lyα
　　　　　　　　　　　　　　　　　　
And Neutral Kα　　 
Origin of 6.7/6.9 keV Line
Charge Exchange or Collisional Excitation ?
Collisional Excitation
 eV
Charge Exchange
 6666eV f r i r
He-like Ka
complex i f l l
He-like Fe Ka = 6680 (+-1) eV：
　 Close to eV in Collisional Excitation

4. Collisional Excitation ?
6.7keV-Map
6.4keV-Map
30 pc
Sgr A*
Charge Exchange or
Collisional Excitation ?
No Correlation
of the 6.7 keV Map with
the 6.4 keV
Cloud (More H2)

5. H-like Ka is very narrow
Fe velocity < 1000 km/s
Lyman Series
n>8  n=1
Collisional Excitation （High Temperature Plasma） is more ｌikely Origin　for 6.7/6.9 keV

6. All the results are consitent with the plasma of kTi ~ kTe=6.5 keV.
Plasma Parameters
Ionization Temperature (kTi)
Fe Kα H-like/He-like: kTi=6.5 keV +/- 0.1 keV
Fe Kβ H-like/He-like: kTi=5.1 keV keV
Ni Kα H-like/He-like : kTi=9.3 keV keV
Electron Temperature (kTe)
He-like Fe Kβ/Kα : kTe=6.2 keV keV
H-like Fe Kβ/Kα : kTe > 6.5 keV (lower limiｔ)
(Centroid of He-like Kα　moves with Ionization temperature
due to the satellite lines)
The Center Energy of Kα (He-like) : kTi= 2.5～6.5 keV
All the results are consitent with the plasma of kTi ~ kTe=6.5 keV.

7. Is this high temperature (6.5 keV) plasma due
to unresolved point sources ?
No it is diffuse.
Temperatures (6.9/6.7) are constant at l=-0.4～+0.1 deg.
The 6.7 keV flux is smooth.
The continuum flux is smooth,
But integrated point source
flux peaks at Sgr A*
6.9/6.7 keV:
Temperature
Sgr A East
Continuum flux
Point source flux
6.7 keV flux
Sgr A East

8. 2. Discovery of New SNR Candidates
6.7 keV map
2.45 keV map

9. 2-temperature + Power-law G0.61+0.01 NH (1022 cm-2) 9.7 (+-0.1)
kTH (keV) 6.0 ( )
kTL (keV) 1.21 ( )
ZS ( )
ZAr ( )
ZCa ( )
ZFe ( )
Γ ( )
Sgr A East G G
NH (1022 cm-2) 16 (23-13)
kT (keV) ( )
ZFe 5.1( )

10. : Interstellar absorption to the GC
NH (1022 cm-2)
8.1 ( )
kT (keV)
0.79 ( )
ZS (solar)
1.1 ( )
Flux (2-10keV)
10-13 ergs/cm2/s
9.4 ( )
Lx (1034 ergs/s)
4.1 G
NH (1022 cm-2) ( )
kT (keV) 0.71( )
All the SNR candidates
have NH ～1023　Hcm-2
: Interstellar absorption
to the GC

11. 3. Discovery of 6.4 keV clumps Origin of the 6.4 keV clumps
Is this Inner shell Ionization　by　Electrons
or X-rays ?
6.4 keV Map

12. Inner Shell Ionization Electrons ｖｓ Ｘ-rays
Equivalent witdh (keV)
of the 6.4 keV line
Energy (keV) of the
Max Cross Section
Absorption Depth NH (cm-2) ～1021 　 ～1024
１０２１
１０２４

13. 6.4 keV Clumps Radio Arc Sgr B1 NH (1022cm-2) (NFe) 22 (19-25)
Power-law (Γ)
1.69 ( )
Line center (eV)
6401 ( )
Equivalent Width (keV)
1.07 ( )
Sgr B1
NH 1022cm-2
18 (13-32)
Power-law Γ
1.3 ( )
line center (eV)
6402 ( )
Equivalent width (keV)
2.1 ( )

14. NH (1022cm-2)
34 ( )
Power-law (Γ)
1.5( )
6.4 keV (eV)
6398 ( )
Equivalent Width (keV)
1.2 ( )
Sgr C M
NH (1022cm-2)
85 ( )
Power-law (Γ)
1.1 ( )
6.4 keV (eV)
6402 ( )
Equivalent Width (keV)
1.7 ( )

15. Sgr B2
NH (1022cm-2)
96(88-121)
Power-law (Γ)
3.2 ( )
6.4 keV (eV)
6399 ( )
Equivalent Width (keV)
1.13 M
NH (1022cm-2)
40 (29-54)
Power-law (Γ)
1.4( )
6.4 keV (eV)
6406 ( )
Equivalent Width (keV)
1.55

16. All
show Kα, Kβ, and K-edge absorption
have equivalent width of 1.1 – 2.1 keV
have K-edge absorption of
1.8 – 9.6 x 1023 cm-2 >> 1 x 1023cm-2
(the interstellar absorption to the GC)
Thus X-ray ionization is more likely.
We further observed large time variability

17. ASCA(1994) Chandra(2000) XMM(2004) Suzaku(2005)
The 6.4 keV map of the Sgr B2 Region changed radmatically
ASCA(1994)　　　　　Chandra(2000)　　　　 XMM(2004) 　　　Suzaku(2005)

18. X-ray Front Sgr B2 M0.74-0.09 Time Variability of Sgr B2 & M0.74-0.09
Suzaku
２００５
X-ray Front
Sgr B2
XMM
２００４
Chandra
２０００
ASCA
１９９４ M
Suzaku
XMM
10 pc
Time Variability
of Sgr B2 & M

19. Galactic Center Diffuse X-rays
Conclusion of the
Galactic Center　Diffuse X-rays
(1) Origin of 6.7/6.9 keV Lines
1-1. High Temperature Plasma in CIE
1-2. Diffuse Emission
(2) We Discovered New SNR Candidates
(3) Origin of the 6.4 keV Line
3-1. X-Ray Reflection
3-2.
The 6.4 keV clumps near Sgr B2 are time
variable reflecting an Outburst of Sg A*.