Is the black hole in GX 339-4 really spinning rapidly?

S. Yamada, K. Makishima, Y. Uehara, K. Nakazawa, H. Takahashi, T. Dotani, Y. Ueda, K. Ebisawa, A. Kubota, P. Gandhi

研究成果: Article

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The wide-band Suzaku spectra of the black hole (BH) binary GX 339-4, acquired in 2007 February during the Very High state, were reanalyzed. Effects of event pileup (significant within ∼3′ of the image center) and telemetry saturation of the X-ray Imaging Spectrometer (XIS) data were carefully considered. The source was detected up to ∼300keV, with an unabsorbed 0.5-200keV luminosity of 3.8 × 1038ergs-1 at 8kpc. The spectrum can be approximated by a power law of photon index 2.7, with a mild soft excess and a hard X-ray hump. When using the XIS data outside 2′ of the image center, the Fe K line appeared extremely broad, suggesting a high BH spin as already reported by Miller etal. based on the same Suzaku data and other CCD data. When the XIS data accumulation is further limited to >3′ to avoid event pileup, the Fe K profile becomes narrower, and a marginally better solution appears which suggests that the inner disk radius is 5-14 times the gravitational radius (1σ), though a maximally spinning BH is still allowed by the data at the 90% confidence level. Consistently, the optically thick accretion disk is inferred to be truncated at a radius 5-32 times the gravitational radius. Thus, the Suzaku data allow an alternative explanation without invoking a rapidly spinning BH. This inference is further supported by the disk radius measured previously in the High/Soft state.

元の言語English
ページ(範囲)L109-L113
ジャーナルAstrophysical Journal
707
発行部数2 PART 2
DOI
出版物ステータスPublished - 2009

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Yamada, S., Makishima, K., Uehara, Y., Nakazawa, K., Takahashi, H., Dotani, T., Ueda, Y., Ebisawa, K., Kubota, A., & Gandhi, P. (2009). Is the black hole in GX 339-4 really spinning rapidly? Astrophysical Journal, 707(2 PART 2), L109-L113. https://doi.org/10.1088/0004-637X/707/2/L109