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

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish
JournalPublications of the Astronomical Society of Japan
Volume64
Issue number1
DOIs
Publication statusPublished - 2012 Feb 25

Keywords

  • Accretion disks
  • Black hole physics
  • Stars: individual (XTE J1752-223)
  • X-rays: stars

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Nakahira, S., Koyama, S., Ueda, Y., Yamaoka, K., Sugizaki, M., Mihara, T., Matsuoka, M., Yoshida, A., Makishima, K., Ebisawa, K., Kubota, A., Yamada, S., Negoro, H., Hiroi, K., Ishikawa, M., Kawai, N., Kimura, M., Kitayama, H., Kohama, M., ... Seta, H. (2012). A spectral study of the black hole candidate XTE J1752-223 in the high/soft state with MAXI, Suzaku, and Swift. Publications of the Astronomical Society of Japan, 64(1). https://doi.org/10.1093/pasj/64.1.13