|
|
論文・著書情報
| タイトル |
| 和文: | |
| 英文: | Low/Hard State Spectra of GRO J1655−40 Observed with Suzaku |
|
| 著者 |
| 和文: |
Takahashi, H.,
Fukazawa, Y.,
Mizuno, T.,
Hirasawa, A.,
Kitamoto, S.,
Sudoh, K.,
Ogita, T.,
Kubota, A.,
Makishima, K.,
Itoh, T.,
Parmar, A. N.,
Ebisawa, K.,
Naik, S.,
Dotani, T.,
Kokubun, M.,
Ohnuki, K.,
Takahashi, T.,
Yaqoob, T.,
Angelini, L.,
Ueda, Y.,
Yamaoka, K.,
Kotani, T.,
河合 誠之,
Namiki, M.,
Kohmura, T.,
Negoro, H..
|
| 英文: |
Takahashi, H.,
Fukazawa, Y.,
Mizuno, T.,
Hirasawa, A.,
Kitamoto, S.,
Sudoh, K.,
Ogita, T.,
Kubota, A.,
Makishima, K.,
Itoh, T.,
Parmar, A. N.,
Ebisawa, K.,
Naik, S.,
Dotani, T.,
Kokubun, M.,
Ohnuki, K.,
Takahashi, T.,
Yaqoob, T.,
Angelini, L.,
Ueda, Y.,
Yamaoka, K.,
Kotani, T.,
Kawai, N.,
Namiki, M.,
Kohmura, T.,
Negoro, H..
|
|
| 言語 |
English |
| 掲載誌/書名 |
| 和文: | |
| 英文: | Publications of the Astronomical Society of Japan |
|
|
巻, 号, ページ
|
Vol. 60
pp. S69-S84
|
| 出版年月 |
2008年2月 |
| 出版者 |
|
| 会議名称 |
|
| 開催地 |
|
| アブストラクト |
The Galactic black-hole binary GRO J1655$-$40 was observed with Suzaku on 2005 September 22--23, for a net exposure of 35 ks with the X-ray Imaging Spectrometer (XIS) and 20 ks with the Hard X-ray Detector (HXD). The source was detected over a broad and continuous energy range of 0.7--300 keV, with an intensity of $\sim$50 mCrab at 20 keV. At a distance of 3.2 kpc, the 0.7--300 keV luminosity is $ \sim 5.1 \times 10^{36}$ erg s$^{-1}$ ($\sim 0.7$ % of the Eddington luminosity for a 6 $M_{\odot}$ black hole). The source was in a typical low/hard state, exhibiting a power-law shaped continuum with a photon index of $\sim 1.6$. During the observation, the source intensity gradually decreased by 25% at energies above $\sim 3$ keV, and by 35% below 2 keV. This, together with the soft X-ray spectra taken with the XIS, suggests the presence of an independent soft component that can be represented by emission from a cool ($\sim 0.2$ keV) disk. The hard X-ray spectra obtained with the HXD reveal a high-energy spectral cutoff, with an e-folding energy of $\sim 200$ keV. Since the spectral photon index above 10 keV is harder by $\sim 0.4$ than that observed in the softer energy band, and the e-folding energy is higher than those of typical reflection humps, the entire 0.7--300 keV spectrum cannot be reproduced by a single thermal Comptonization model, even considering reflection effects. Instead, the spectrum (except the soft excess) can be successfully explained by invoking two thermal-Comptonization components with different $y$-parameters. In contrast to the high/soft state spectra of this object in which narrow iron absorption lines are detected with equivalent widths of 60--100 eV, the present XIS spectra bear no such features beyond an upper-limit equivalent width of 25 eV. |
|
各種検索
サポート
ヘルプ