A spectral study of the black hole candidate XTE J1752-223 in the high/soft state with MAXI, Suzaku, and Swift

Satoshi Nakahira, Shu Koyama, Yoshihiro Ueda, Kazutaka Yamaoka, Mutsumi Sugizaki, Tatehiro Mihara, Masaru Matsuoka, Atsumasa Yoshida, Kazuo Makishima, Ken Ebisawa, Aya Kubota, Shin'ya Yamada, Hitoshi Negoro, Kazuo Hiroi, Masaki Ishikawa, Nobuyuki Kawai, Masashi Kimura, Hiroki Kitayama, Mitsuhiro Kohama, Takanori MatsumuraMikio Morii, Motoki Nakajima, Motoko Serino, Megumi Shidatsu, Tetsuya Sootome, Kousuke Sugimori, Fumitoshi Suwa, Hiroshi Tomida, Yoko Tsuboi, Hiroshi Tsunemi, Shiro Ueno, Ryuichi Usui, Takayuki Yamamoto, Kyohei Yamazaki, Makoto S. Tashiro, Yukikatsu Terada, Hiromi Seta

研究成果: Article査読

抄録

We report on an X-ray spectral analysis of the black hole candidate XTE J1752-223 in the 2009-2010 outburst, utilizing data obtained with the MAXI/Gas Slit Camera (GSC), the Swift/XRT, and Suzaku, which work comple-mentarily. As already reported by Nakahira et al. (2010, PASJ, 62, L27), MAXI monitored the source continuously throughout the entire outburst for about eight months. All of the MAXI/GSC energy spectra in the high/soft state, lasting for 2 months, are well represented by a multi-color disk plus power-law model. The innermost disk temperature changed from ∼0.7 keV to ∼0.4 keV and the disk flux decreased by an order of magnitude. Nevertheless, the innermost radius is constant at ∼41 D3.5(cos i)-1/2km, where D 3.5 is the source distance in units of 3.5kpc and i the inclination. The multi-color disk parameters obtained with the MAXI/GSC are consistent with those with the Swift/XRT and Suzaku. The Suzaku data also suggest a possibility that the disk emission is slightly Comptonized, which could account for broad iron-K features reported previously. Assuming that the obtained innermost radius represents the innermost stable circular orbit for a non-rotating black hole, we estimate the mass of the black hole to be 5.51 ± 0.28 M D3.5(cos -1/2, where the correction for the stress-free inner boundary condition and color hardening factor of 1.7 are taken into account. If the inclination is less than 49°, as suggested from radio monitoring of transient jets, and the soft-to-hard transition in 2010 April occurred at 1%-4% of Eddignton luminosity, the fitting of the Suzaku spectra with a relativistic accretion-disk model derives constraints on the mass and the distance to be 3.1-55M and 2.3-22 kpc, respectively. This confirms that the compact object in XTE J1752-223 is a black hole.

本文言語English
ジャーナルPublications of the Astronomical Society of Japan
64
1
DOI
出版ステータスPublished - 2012 2 25

ASJC Scopus subject areas

  • 天文学と天体物理学
  • 宇宙惑星科学

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