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

Contents of the Talk 1.Properties of the Seyfert Galaxies 2.Variable Partial Covering Model 3.Explanation of the Observed Properties 4.Conclusion 2

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

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

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

1c. Small variation in the iron energy band MCG with ASCA Energy dependence of Root Mean Square (RMS) variation The RMS spectrum drops significantly at the iron K energy band (model independent result!) (Matsumoto+ 2003) 〜 10 5 sec 〜 10 4 sec 6

Contents of the Talk 1.Properties of the Seyfert Galaxies 2.Variable Partial Covering Model 3.Explanation of the Observed Properties 4.Conclusion 7

2. Variable Partial Covering Model Several authors have proposed idea of partial covering for MCG : 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 spectra (Miyakawa, Ebisawa and Inoue 2012) 8

Double partial covering 9 X-ray source xspec notation: partcov(  ) * exp(-N H  (  )) × partcov(  ) exp(-N H  (  )) Partial covering by thick absorber with N H ~ cm -2 and  ~ and the partial covering fraction  Partial covering by thin and more ionized absorber with N H ~ cm -2 and  ~ and the same partial covering fraction 

2. Variable Partial Covering Model Observed spectral variation of MCG 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 in prep.). 10

11 Miyakawa, Ebisawa and Inoue (2012)

Outer disk reflection Direct component Heavily absorbed component 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 by only change of the covering fraction α 2. Variable Partial Covering Model 12

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

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

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

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

Contents of the Talk 1.Properties of the Seyfert Galaxies 2.Variable Partial Covering Model 3.Explanation of the Observed Properties 4.Conclusion 20

解析 Counting rate Covering fraction Flux variation of 21 Seyfert galaxies observed with Suaku, explained by only change of the covering fraction Explanation of the Observed Properties a. Significant flux variation

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

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

direct component outer-reflection component Heavily absorbed component narrow ion line The ionized iron-edge looks like a broad iron line feature Explanation of the Observed Properties b. “Seemingly” broad iron-line feature Suzaku MCG Miyakawa, Ebisawa and Inoue (2012)

3. Explanation of the Observed Properties c. 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 27

3. Explanation of the Observed Properties c. 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 Iron line reflection absorbed component direct compoent

解析 Observed Root Mean Square spectrum is explained by only variation of the covering fraction Explanation of the Observed Properties c. Small variation in the iron energy band 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

Contents of the Talk 1.Properties of the Seyfert Galaxies 2.Variable Partial Covering Model 3.Explanation of the Observed Properties 4.Conclusion 33

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 absorbers in 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 ) observed with Suzaku. 34