1. Suzaku Observations of our Milky Way Center
Katsuji Koyama Kyoto University, JAPAN

2. Spacecraft and Instruments 6.5m 1700kg X-ray Telescope(XRT) 1.9m2
Spacecraft and
　　Instruments
6.5m
1700kg
X-ray Telescope(XRT)
(4units for XIS, 1unit for XRS)NASA/GSFC
-Nagoya-ISAS/JAXA
1.9m
Hard X-ray Detector HXD
Tokyo-ISAS/JAXA-Riken-Saitama-Hiroshima-Kanazawa-...
X-Ray CCD * XIS
MIT-Osaka-Kyoto
- ISAS/JAXA
X-ray Micro Calorimeter: XRS NASA/GSFC-Wisconsin
-ISAS/JAXA-Tokyo Metro.

3. Plasma Parameters ~0.70° ~0.36°
T ~ 108 K
L2-10 ~ 2x1036ergs/s
Size ~ 50pc x 30pc
nave ~ 0.1cm-3
npeak ~ 0.4cm-3
Egas ~ 3x1052ergs
~0.70°
~0.36°
R: 6.7keV, G:2.45keV, B: 6.4keV
Escape Time scale: tesc = Size/Cs = 2x104yr
Heating Rate = Egas/tesc~5x1040ergs/s~10-3 SN yr -1
Very High !
(1) High SN rate ! Many SNRs in the GC
(2) Past Activities (Flares) of the Super massive black hole
Sgr A*
(eg. Koyama+96)

4. Spatial Distribution of the Galactic Diffuse X-Rays and Time Variability of the 6.4-keV Clumps
(1) Diffuse ? or
Integrated
point sources ?
X-ray
reflection ?
by Sgr A* ? GC
2.5 keV (He-like S)
6.7 keV (He-like Fe)
6.4 keV (Neutral Fe)

5. l-distribution b-distribution Point source Flux (4.8-8 keV)
The 6.7 keV line flux vs
Integrated point source flux
(Chandra deep exposure)
near　GC ( |I| < 0.3 deg)
l-distribution b-distribution
Sgr A*
Point source Flux (4.8-8 keV)
( ｂ)

6. The ６．４keV Clump
EW=1.8 keV
EW=1.8 keV M M

7. (1.5 sigma for the 6.7 keV line)
6.4 keV Line is time variable. (Muno et al. 2007)
A Clump near the Radio Arc　
Chandra (2002)
Suzaku (2005)
Sgr A*
Sgr A*
Chandra (2002) Suzaku (2005)
6.4 keV line *
(10-5 photons s-1cm-2)
* 4.7 sigma variability
(1.5 sigma for the 6.7 keV line)

8. The Sgr B2 Cloud This flux change can not be explained by electrons.
Variability time
scale of the 6.4
keV flux ~ ys
(Inui et al. 2008)
M 0.66
G 0.570
~10pc
This flux change
can not be
explained by
electrons.
We need X-ray
irradiation.
Where is the
X-ray source ?

9. 1994年
X-ray front
2000年
2004年
2005年

10. 2ay=x2 - a2: a = 300 light-years
Sgr A*
If the X-ray front has a narrow width ~10 ly,
then X-ray reflection zone is parabola, where
the origin of the coordinate is Sgr A*

11. ＊
Sawada et al. 2004

12. Conclusions Integrated flux of point sources
contributes a small fraction of the total
Galactic center X-rays (GCX).
(2) Major fraction of the GCX is diffuse .
(3) 6.4 keV line clumps are time variable,
hence the most probable origin is X-ray
reflection by the past active Sgr A*