Post on 21-Jan-2016
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Origin of the X-ray Spectral Variation and Seemingly Broad Iron Line
Structure in the Seyfert GalaxiesKen EBISAWA
Naoki ISO, Takehiro MIYAKAWA, Hajime INOUE
(JAXA/ISAS)
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Contents of the Talk
1. Properties of the Seyfert Galaxies2. Variable Partial Covering Model3. Explanation of the Observed Properties4. Conclusion
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1. Properties of the Seyfert Galaxies
a) Significant flux variationb) “Seemingly” broad iron-line featurec) Small variation in the iron energy band
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1a. Significant flux-variation
Suzaku observations of NGC4051 and NGC3516 (0.2—12 keV, 1bin=512sec)
Significant and aperiodic variations in various time-scales
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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
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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!)
(Matsumoto+ 2003)
〜 105 sec
〜 104 sec
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Contents of the Talk
1. Properties of the Seyfert Galaxies2. Variable Partial Covering Model3. Explanation of the Observed Properties4. Conclusion
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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)
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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~101.6 and the partial covering fraction a
Partial covering by thin and more ionized absorber with NH~1022.1cm-2 and x~101.9 and the same partial covering fraction a
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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)
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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
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direct component
Heavily absorbed
component
X-ray source
Ionized absorbers
Variable Partial Covering Model(Miyakawa, Ebisawa and Inoue 2012)
The X-ray luminosity of BH hardly variableGeometrical “covering fraction” is significantly variable
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Variable Partial Covering Model(Miyakawa, Ebisawa and Inoue 2012)
The X-ray luminosity of BH hardly variableGeometrical “covering fraction” is significantly variable
Covering fraction varies
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Covering fraction varies
Variable Partial Covering Model(Miyakawa, Ebisawa and Inoue 2012)
The X-ray luminosity of BH hardly variableGeometrical “covering fraction” is significantly variable
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Variable Partial Covering Model(Miyakawa, Ebisawa and Inoue 2012)
The X-ray luminosity of BH hardly variableGeometrical “covering fraction” is significantly variable
Covering fraction varies
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Variable Partial Covering Model(Miyakawa, Ebisawa and Inoue 2012)
The X-ray luminosity of BH hardly variableGeometrical “covering fraction” is significantly variable
Covering fraction varies
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Variable Partial Covering Model(Miyakawa, Ebisawa and Inoue 2012)
The X-ray luminosity of BH hardly variableGeometrical “covering fraction” is significantly variable
Covering fraction varies
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Covering fraction: Null
Variable Partial Covering Model(Miyakawa, Ebisawa and Inoue 2012)
The X-ray luminosity of BH hardly variableGeometrical “covering fraction” is significantly variable
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Contents of the Talk
1. Properties of the Seyfert Galaxies2. Variable Partial Covering Model3. Explanation of the Observed Properties4. Conclusion
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解析
Counting rate
Covering fraction
Flux variation of 21 Seyfert galaxies observed withSuaku, explained by only change of the covering fraction
3. Explanation of the Observed Propertiesa. Significant flux variation
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Observed flux variations explained by “constant black hole luminosity and variable covering fraction”.
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Example of other sourcesBlack:countig rateRed:covering fraction
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Example of other sourcesBlack:countig rateRed:covering fraction
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Example of other sourcesBlack:countig rateRed:covering fraction
direct component
outer-reflection component
Heavily absorbed component
narrow ion line
The ionized iron-edge looks like a broad iron line feature
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3. Explanation of the Observed Propertiesb. “Seemingly” broad iron-line feature
Suzaku MCG-6-30-15Miyakawa, Ebisawa and Inoue (2012)
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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
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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
Iron linereflection
absorbed component
direct compoent
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解析
• Observed Root Mean Square spectrum is explained by only variation of the covering fraction
3. Explanation of the Observed Propertiesc. Small variation in the iron energy band
Black:dataRed:model
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Example of other sourcesBlack:dataRed:model
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Example of other sourcesBlack:dataRed:model
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Example of other sourcesBlack:dataRed:model
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Contents of the Talk
1. Properties of the Seyfert Galaxies2. Variable Partial Covering Model3. Explanation of the Observed Properties4. Conclusion
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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-6-30-15) observed with Suzaku.