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Title: SUZAKU VIEW OF X-RAY SPECTRAL VARIABILITY OF THE RADIO GALAXY CENTAURUS A: PARTIAL COVERING ABSORBER, REFLECTOR, AND POSSIBLE JET COMPONENT

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 {approx}0.2 than that of the time-averaged spectra in 2009. This suggests anmore » 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.« less

Authors:
; ; ; ; ; ; ; ;  [1]
  1. Department of Physical Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan)
Publication Date:
OSTI Identifier:
22004479
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 743; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; GAMMA RADIATION; PHOTONS; RADIO GALAXIES; TELESCOPES; X-RAY GALAXIES

Citation Formats

Fukazawa, Yasushi, Hiragi, Kazuyoshi, Yamazaki, Syoko, Mizuno, Motohiro, Hayashi, Kazuma, Hayashi, Katsuhiro, Nishino, Sho, Takahashi, Hiromitsu, and Ohno, Masanori, E-mail: fukazawa@hep01.hepl.hiroshima-u.ac.jp. SUZAKU VIEW OF X-RAY SPECTRAL VARIABILITY OF THE RADIO GALAXY CENTAURUS A: PARTIAL COVERING ABSORBER, REFLECTOR, AND POSSIBLE JET COMPONENT. United States: N. p., 2011. Web. doi:10.1088/0004-637X/743/2/124.
Fukazawa, Yasushi, Hiragi, Kazuyoshi, Yamazaki, Syoko, Mizuno, Motohiro, Hayashi, Kazuma, Hayashi, Katsuhiro, Nishino, Sho, Takahashi, Hiromitsu, & Ohno, Masanori, E-mail: fukazawa@hep01.hepl.hiroshima-u.ac.jp. SUZAKU VIEW OF X-RAY SPECTRAL VARIABILITY OF THE RADIO GALAXY CENTAURUS A: PARTIAL COVERING ABSORBER, REFLECTOR, AND POSSIBLE JET COMPONENT. United States. doi:10.1088/0004-637X/743/2/124.
Fukazawa, Yasushi, Hiragi, Kazuyoshi, Yamazaki, Syoko, Mizuno, Motohiro, Hayashi, Kazuma, Hayashi, Katsuhiro, Nishino, Sho, Takahashi, Hiromitsu, and Ohno, Masanori, E-mail: fukazawa@hep01.hepl.hiroshima-u.ac.jp. Tue . "SUZAKU VIEW OF X-RAY SPECTRAL VARIABILITY OF THE RADIO GALAXY CENTAURUS A: PARTIAL COVERING ABSORBER, REFLECTOR, AND POSSIBLE JET COMPONENT". United States. doi:10.1088/0004-637X/743/2/124.
@article{osti_22004479,
title = {SUZAKU VIEW OF X-RAY SPECTRAL VARIABILITY OF THE RADIO GALAXY CENTAURUS A: PARTIAL COVERING ABSORBER, REFLECTOR, AND POSSIBLE JET COMPONENT},
author = {Fukazawa, Yasushi and Hiragi, Kazuyoshi and Yamazaki, Syoko and Mizuno, Motohiro and Hayashi, Kazuma and Hayashi, Katsuhiro and Nishino, Sho and Takahashi, Hiromitsu and Ohno, Masanori, E-mail: fukazawa@hep01.hepl.hiroshima-u.ac.jp},
abstractNote = {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 {approx}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.},
doi = {10.1088/0004-637X/743/2/124},
journal = {Astrophysical Journal},
number = 2,
volume = 743,
place = {United States},
year = {Tue Dec 20 00:00:00 EST 2011},
month = {Tue Dec 20 00:00:00 EST 2011}
}