論文

査読有り
2010年4月

Probing the Peculiar Behavior of GRS 1915+105 at Near-Eddington Luminosity

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN
  • Kiki Vierdayanti
  • ,
  • Shin Mineshige
  • ,
  • Yoshihiro Ueda

62
2
開始ページ
239
終了ページ
253
記述言語
英語
掲載種別
研究論文(学術雑誌)
DOI
10.1093/pasj/62.2.239
出版者・発行元
OXFORD UNIV PRESS

To understand the nature of supercritical accretion, we systematically analyzed the RXTE/PCA data of GRS 1915+105 in its quasi-steady states, by choosing data with small variability during 1999-2000. We applied a multicolor disk plus a thermal Comptonization model, and took into consideration accurate interstellar absorption, a reflection component (with an iron-K emission line), and absorption features from the disk wind self-consistently. The total luminosity ranges from similar to 0.2L(E) to slightly above L-E. There is a strong correlation between the inner disk temperature and the fraction of the disk component. Most of the Comptonization-dominated (> 50% total flux) spectra show T-in similar to 1 keV with a high electron temperature of > 10 keV, which may correspond to the very high state in canonical black hole X-ray binaries (BHBs). In contrast, the disk-dominated spectra have T-in similar to 2 keV with a low temperature (< 10 keV) and optically thick Comptonization, and show two separate branches in the luminosity vs. innermost temperature (L-T-in) diagram. The lower branch clearly follows the L alpha T-in(4)-track. Furthermore, by applying the extended disk blackbody (or p-free disk) model, we found that 9 out of 12 datasets with disk luminosity above 0.3 L-E prefer a flatter temperature gradient than that in the standard disk (p < 0.7). We interpret that, in the lower branch, the disk extends down to the innermost stable circular orbit, and the source is most probably in the slim-disk state. A rapidly spinning black hole can explain both the lack of the L alpha T-in(2)-track and a high value of the spectral hardening factor (similar to 4) that would be required for a non-rotating black hole. The spectra in the upper branch are consistent with the picture of a truncated disk with low-temperature Comptonization. This state was uniquely observed from GRS 1915+105 among BHBs, which may be present at near-Eddington luminosity.

リンク情報
DOI
https://doi.org/10.1093/pasj/62.2.239
CiNii Articles
http://ci.nii.ac.jp/naid/10026714463
Web of Science
https://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=JSTA_CEL&SrcApp=J_Gate_JST&DestLinkType=FullRecord&KeyUT=WOS:000279834900005&DestApp=WOS_CPL
ID情報
  • DOI : 10.1093/pasj/62.2.239
  • ISSN : 0004-6264
  • eISSN : 2053-051X
  • CiNii Articles ID : 10026714463
  • Web of Science ID : WOS:000279834900005

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