X-Ray spectral variability of the seyfert galaxy NGC 4051 observed with Suzaku

Yuichi Terashima, Luigi C. Gallo, Hirohiko Inoue, Alex G. Markowitz, James N. Reeves, Naohisa Anabuki, Andrew C. Fabian, Richard E. Griffiths, Kiyoshi Hayashida, Takeshi Itoh, Norihide Kokubun, Aya Kubota, Giovanni Miniutti, Tadayuki Takahashi, Makoto Yamauchi, Daisuke Yonetoku

研究成果: Article査読

27 被引用数 (Scopus)


We report on results from a Suzaku observation of the narrow-line Seyfert 1 NGC 4051.During our observation, large-amplitude rapid variability was seen, and the averaged 2-10keV flux was 8.1 × 10-12ergs-1 cm-2, which is several times lower than the historical average. The X-ray spectrum hardens when the source flux becomes lower, confirming the trend of spectral variability known for many Seyfert 1 galaxies. The broad-band averaged spectrum and spectra in high- and low-flux intervals were analyzed. The spectra were first fitted with a model consisting of a power-law component, a reflection continuum originating in cold matter, a blackbody component, two zones of ionized absorber, and several Gaussian emission lines. The amount of reflection is rather large (R ̃ 7, where R = 1 corresponds to reflection by an infinite slab), while the equivalent width of the Fe-K line at 6.4 keV is modest (140eV) for the averaged spectrum. We then modeled the overall spectra by introducing partial covering for the power-law component and reflection continuum independently. The column density for the former is 1 × 10 23 cm-2, while it is fixed at 1 x 1024cm -2 for the latter. By comparing the spectra in different flux states, we could identify the causes of spectral variability.

ジャーナルPublications of the Astronomical Society of Japan
出版ステータスPublished - 2009

ASJC Scopus subject areas

  • 天文学と天体物理学
  • 宇宙惑星科学


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