1. Spatial Distribution of the Galactic Diffuse X-Rays and Time Variability of the 6.4-keV Clumps
Katsuji Koyama
Kyoto University
X-ray or
Electron
irradiation ?
(1) Diffuse ? or
Integrated
point sources ? GC
2.5 keV (He-like S)
6.7 keV (He-like Fe)
6.4 keV (Neutral Fe)

2. 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*
10 x 6.7 keV line (EW=0.5 keV)
Point source Flux (4.8-8 keV)
( ｂ)

3. The 6.7 and 6.96 keV lines in GC and GR 6.7 keV line : Point-sources:
Exponential
FWHM ~ 0.2 deg
6.7keV lines
Point-sources:
power-law
index = 0.9
(Infrared star numbers,
Chandra point sources)
6.96/6.7 keV
Temperature
F6.96/F6.7 ~ (GC)
~ (GR)

4. Gamma is constant (~1.9) (independent of F6.4/F6.7)
Made 2 x 16 spectra
and fit with a model of
Power-law + Gaussian lines
Gamma, Fluxes (F) and
Equivalent width (EW)
Gamma :Power-law Index
F : 5-10 keV band
F6.4 , EW6.4 : 6.4 keV line
F6.7 , EW6.7 : 6.7 keV line
Gamma is
constant (~1.9)
(independent
of F6.4/F6.7)
F6.4/F6.7 vs Gamma
Gamma
F6.4/F6.7

5. EW EW6.4 = Constant
100F6.7
10F6.4
Phenomenologically, about 2/3
(1/1.5) of the 5-10 keV flux is
associated to the 6.7 keV line
and the other 1/3 (0.5/1.5)
is associated to the 6.4 keV line.
Koyama te al. 2008
F F6.4
F5-10

6. 2 x 1.9 + 0.9 ~ 3x 1.4 4 x 1.9 - 0.9 ~ 3x 2.4 6.7 keV “Territory”
Muno et al.
2004
Koyama et al. 2008

7. The 6.4 keV Clump
EW=1.8 keV
EW=1.8 keV M M

8. (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)

9. 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 ?

10. 1994年
X-ray front
2000年
2004年
2005年

11. 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*

12. ＊
Sawada et al. 2004

13. Conclusions Integrated flux of point sources
contributes ~1/6 of the total Galactic
center X-rays (GCX).
(2) Major fraction of the GCX is diffuse .
(3) Plasma temperature of the GC
is probably higher than that of the GR.
(4) 6.4 keV line clumps are time variable,
hence the most probable origin is X-ray
reflection.