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1) Origin of 6.7/6.9 keV (He-like/H-like Fe Ka) Lines

Spectroscopic Study of the Galactic Center X-Rays with Suzaku Katsuji Koyama, Kyoto University. 1) Origin of 6.7/6.9 keV (He-like/H-like Fe Ka) Lines : Collisional Excitation or Charge Exchange 2) Discoveries of New SNR Candidates 3) Origin of 6.4 keV (Neutral Fe Ka) Line

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1) Origin of 6.7/6.9 keV (He-like/H-like Fe Ka) Lines

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  1. Spectroscopic Study of the Galactic Center X-Rays with Suzaku Katsuji Koyama, Kyoto University • 1) Origin of 6.7/6.9 keV (He-like/H-like Fe Ka) Lines • : Collisional Excitation or Charge Exchange • 2) Discoveries of New SNR Candidates • 3) Origin of 6.4 keV (Neutral Fe Ka) Line • : X-Ray Reflection or Electron Bremsstrahｌung • : Time Variability of the 6.4 keV clumps • How reliable our “Energy scale calibration” is. • (For detail, please read PASJ special issue)

  2. H-like Observed (eV) Lab D(eV) ----------------------------- S Lya2622 (+4-3) 2622 0 Fe Lya 6970 (+3-2) 6966 4 Mn Ka 5900 (+2-1) 5895 5 Energy Scale Check Using the H-like Lya 　　　　　　　　　　　　　　  andNeutral Ka　　  Origin of the 6.7 keV (He-like Fe Ka) Line Charge Exchange or Collisional Excitation ? Collisional Excitation  6680-6685 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 6680-6685eV in Collisional Excitation

  3. 6.9 keV (H-like Lya) is very narrow < 20 eV = Fe velocity < 1000 km/s Lyman Series n>8  n=1 Collisional Excitation （High Temperature Plasma） is more ｌikely Originfor 6.9 keV

  4. Parametersof the GC plasma Ionization Temperature (kTi) Fe KaH-like/He-like: kTi=6.5 keV +/- 0.1 keV Fe Kb H-like/He-like: kTi=5.1 keV + 1.5 -1.0 keV Ni Ka H-like/He-like : kTi=9.3 keV +1.6 -2.5 keV Electron Temperature (kTe) He-like Fe Kb/Ka : kTe=6.2 keV +3 -1 keV H-like Fe Kb/Ka : kTe > 6.5 keV (lower limiｔ) Centroid of He-like Kamoves with Ionization temperature due to the satellite lines. The Center Energy of Ka (He-like) : kTi= 2.5-6.5 keV All the results are consitent with the plasma of kTi = kTe (CIE) = 6.5 keV.

  5. 2. Discovery of New SNR Candidates 6.7 keV map Sgr A East 2.45 keV map

  6. 6.4 keV Map 3. Discovery of 6.4 keV clumps Origin of the 6.4 keV clumps Is this Inner shell IonizationbyElectrons or X-rays ?

  7. Inner Shell Ionization Electrons ｖｓ　Ｘ-rays --------------------------------------------- Equivalent witdh (keV) of the 6.4 keV line 0.3 - 0.6 1 - 1.5 Energy (keV) of the Max Cross Section 10-100 7.1 Absorption NH (cm-2) ~1021~1024 Electron X-ray １０２１ １０２４

  8. Most of the 6.4 keV clumps show strong Ka line with the equivalent width of 1.1 – 2.1 keV ,and deep K-edge absorption with 2 – 10 x 1023 cm-2 >> 1 x 1023cm-2 ( the interstellar absorption to the GC) Thus ionization by X-rays is more likely. Further more We found a large time variability.

  9. G0.570 Sgr B2 ~10pc 6.4 keV line History of Sgr B2 from 1994 to 2005

  10. 6.4 keV 6.4 keV 6.7 keV 6.7keV 6.4keV: Full region 6.4keV: Sgr B2 cloud 6.7keV: Full region 6.4keV: G 0.570-0.018

  11. Physical size of the clump complex is nearly 10 pc. Therefore, such a large flux change within 10 years is impossible by any charged particle. Only possible scenario of this time variability is due to an irradiation of variable X-rays (X-ray Reflection Nebula). More than a few hundred years ago, Sgr A* had been very active in X-rays; it was 106 times brighter than present at ~300 years ago, and decayed to less than a half after ~10 years. The X-rays hit the Sgr B clouds after ~300-years travel. The clouds re-emitted the 6.4 keV photons. Like a time delayed-echo, the X-ray echo is now just arriving at the Earth, when Sgr A* is falling into a quiescent state.

  12. Conclusion of the Galactic CenterDiffuse X-rays (1) Origin of the 6.7/6.9 keV Lines High Temperature Plasma in CIE (2) We have discovered New SNR Candidates (3) Origin of the 6.4 keV Line X-Ray Reflection The 6.4 keV clumps near Sgr B2 are time variable as a reflection of a past outburst of Sg A*

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