Ken EBISAWA Naoki ISO, Takehiro MIYAKAWA, Hajime INOUE (JAXA/ISAS)

1. Origin of the X-ray Spectral Variation and Seemingly Broad Iron Line Structure in the SeyfertGalaxies Ken EBISAWA Naoki ISO, Takehiro MIYAKAWA, Hajime INOUE (JAXA/ISAS)

2. Contents of the Talk • Properties of the Seyfert Galaxies • Variable Partial Covering Model • Explanation of the Observed Properties • Conclusion

3. 1. Properties of the Seyfert Galaxies • Significant flux variation • “Seemingly” broad iron-line feature • Small variation in the iron energy band

4. 1a. Significant flux-variation Suzaku observations of NGC4051 and NGC3516(0.2—12 keV, 1bin=512sec） Significant and aperiodic variations in various time-scales

5. 1b.“Seemingly” broad iron-line feature • ASCA MCG-6-30-15 (Tanaka+ 1995) • Looks like an iron K-line“broadened” by relativistic effects • Interpretation depends on the choice of models

6. 1c. Small variation in the iron energy band • MCG-6-30-15 with ASCAEnergy dependence of Root Mean Square (RMS) variation • The RMS spectrum drops significantly at the iron K energy band (model independent result!) 〜104 sec 〜105 sec (Matsumoto+ 2003)

7. Contents of the Talk • Properties of the Seyfert Galaxies • Variable Partial Covering Model • Explanation of the Observed Properties • Conclusion

8. 2. Variable Partial Covering Model • Several authors have proposed idea of partial covering for MCG-6-30-15: e.g., Matsuoka+ (1990); McKernan and Yaqoob (1998); Miller, Turner and Reeves (2008, 2009) • We have found “double partial covering” with two different warm absorbers can explain the Suzaku MCG-6-30-15 spectra (Miyakawa, Ebisawa and Inoue 2012)

9. Double partial covering X-ray source xspec notation: partcov(a) * exp(-NHs(x))×partcov(a) exp(-NHs(x)) Partial covering by thick absorber with NH~1024.2cm-2 and x~101.6and the partial covering fraction a Partial covering by thin and more ionized absorber with NH~1022.1cm-2 and x~101.9and the same partial covering fraction a

10. 2. Variable Partial Covering Model • Observed spectral variation of MCG-6-30-15 is mostly explained by only variation of the partial covering fraction(Miyakawa, Ebisawa and Inoue 2012, PASJ, 64, 140) • Variable Partial Covering model can explain spectral variations of other 20 Seyfert galaxies observed with Suzaku(Iso, Ebisawa+ 2013 in prep.).

11. Miyakawa, Ebisawa and Inoue (2012)

12. 2. Variable Partial Covering Model • Double Partial covering by absorbing clouds with thick core and thin envelope. • The continuum spectrum composed of the direct component, absorbed component, and outer-disk reflection component • Observed spectral variation is mostly explained byonly change of the covering fractionα Direct component Heavily absorbed component Outer disk reflection

13. Variable Partial Covering Model (Miyakawa, Ebisawa and Inoue 2012) The X-ray luminosity of BH hardly variable Geometrical “covering fraction” is significantly variable X-ray source direct component Heavily absorbed component Ionized absorbers

14. Variable Partial Covering Model (Miyakawa, Ebisawa and Inoue 2012) The X-ray luminosity of BH hardly variable Geometrical “covering fraction” is significantly variable Covering fraction varies

15. Variable Partial Covering Model (Miyakawa, Ebisawa and Inoue 2012) The X-ray luminosity of BH hardly variable Geometrical “covering fraction” is significantly variable Covering fraction varies

16. Variable Partial Covering Model (Miyakawa, Ebisawa and Inoue 2012) The X-ray luminosity of BH hardly variable Geometrical “covering fraction” is significantly variable Covering fraction varies

17. Variable Partial Covering Model (Miyakawa, Ebisawa and Inoue 2012) The X-ray luminosity of BH hardly variable Geometrical “covering fraction” is significantly variable Covering fraction varies

18. Variable Partial Covering Model (Miyakawa, Ebisawa and Inoue 2012) The X-ray luminosity of BH hardly variable Geometrical “covering fraction” is significantly variable Covering fraction varies

19. Variable Partial Covering Model (Miyakawa, Ebisawa and Inoue 2012) The X-ray luminosity of BH hardly variable Geometrical “covering fraction” is significantly variable Covering fraction: Null

20. Contents of the Talk • Properties of the Seyfert Galaxies • Variable Partial Covering Model • Explanation of the Observed Properties • Conclusion

21. 解析 3. Explanation of the Observed Propertiesa. Significant flux variation Flux variation of 21 Seyfert galaxies observed withSuaku, explained by only change of the covering fraction Counting rate Covering fraction

22. Observed flux variations explained by “constant black hole luminosity and variable covering fraction”.

23. Example of other sources Black:countig rate Red:covering fraction

24. Example of other sources Black:countig rate Red:covering fraction

25. Example of other sources Black:countig rate Red:covering fraction

26. 3. Explanation of the Observed Propertiesb. “Seemingly” broad iron-line feature The ionized iron-edge looks like a broad iron line feature direct component Heavily absorbed component outer-reflection component narrow ion line Suzaku MCG-6-30-15 Miyakawa, Ebisawaand Inoue (2012)

27. 3. Explanation of the Observed Propertiesc. Small variation in the iron energy band • In the Variable Partial Covering model, variations of the direct component and absorbed component cancel each other • This is most effective at the iron energy band

28. 3. Explanation of the Observed Propertiesc. Small variation in the iron energy band • In the Variable Partial Covering model, variations of the direct component and absorbed component cancel each other • This is most effective at the iron energy band direct compoent absorbed component reflection Iron line

29. 解析 3. Explanation of the Observed Propertiesc. Small variation in the iron energy band • Observed Root Mean Square spectrum is explained by only variation of the covering fraction Black:data Red:model

30. Example of other sources Black:data Red:model

31. Example of other sources Black:data Red:model

32. Example of other sources Black:data Red:model

33. Contents of the Talk • Properties of the Seyfert Galaxies • Variable Partial Covering Model • Explanation of the Observed Properties • Conclusion

34. 4. Conclusion • We propose “Variable Partial Covering model” for Seyfert Galaxies, where X-ray luminosity of the black hole is hardly variable, and the observed spectral variation is primarily due to variation of the warm absorbersin the line of sight. • In the Variable Partial Covering model, covering fraction is the primary parameter to describe the spectral variations. • The Variable Partial Covering model successfully explains observed spectral variations of 21 Seyfert galaxies (including MCG-6-30-15) observed with Suzaku.