Suzaku view of X-ray Spectral Variability of the Radio Galaxy Centaurus A : Partial Covering Absorber, Reflector, and Possible Jet Component
Use this link to cite this item : https://ir.lib.hiroshima-u.ac.jp/00034772
ID | 34772 |
file | |
creator |
Hiragi, Kazuyoshi
Yamazaki, Syoko
Mizuno, Motohiro
Hayashi, Kazuma
Hayashi, Katsuhiro
Nishino, Sho
Ohno, Masanori
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subject | galaxies: active
galaxies: individual (Centaurus A)
galaxies: Seyfert
X-rays: galaxies
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NDC |
Astronomy. Space sciences
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abstract | We observed a nearby radio galaxy, Centaurus A (Cen A), three times with Suzaku in 2009 and measured the wide-band X-ray spectral variability more accurately than previous measurements. The Cen A was in an active phase in 2009, and the flux became higher by a factor of 1.5-2.0 and the spectrum became harder than that in 2005. The Fe-K line intensity increased by 20%-30% from 2005 to 2009. The correlation of the count rate between the XIS 3-8 keV and PIN 15-40 keV band showed a complex behavior with a deviation from a linear relation. The wide-band X-ray continuum in 2-200 keV can be fitted with an absorbed power-law model plus a reflection component, or a power law with a partial covering Compton-thick absorption. The difference spectra between high and low flux periods in each observation were reproduced by a power law with a partial covering Compton-thick absorption. Such a Compton-thick partial covering absorber was observed for the first time in Cen A. The power-law photon index of the difference spectra in 2009 is almost the same as that of the time-averaged spectra in 2005, but steeper by similar to 0.2 than that of the time-averaged spectra in 2009. This suggests an additional hard power-law component with a photon index of <1.6 in 2009. This hard component could be a lower part of the inverse-Compton-scattered component from the jet, whose gamma-ray emission has recently been detected with the Fermi Large Area Telescope.
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journal title |
The Astrophysical Journal
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volume | Volume 743
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issue | Issue 2
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start page | 124
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date of issued | 2011
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publisher | IOP Publishing Ltd
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issn | 0004-637X
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ncid | |
publisher doi | |
language |
eng
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nii type |
Journal Article
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HU type |
Journal Articles
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DCMI type | text
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format | application/pdf
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text version | publisher
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rights | (c) 2011. The American Astronomical Society. All rights reserved.
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relation url | |
department |
Graduate School of Science
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