A Spectral Study of the Black Hole Candidate XTE J1752-223 in the High/Soft State with MAXI, Suzaku, and Swift

作者：Nakahira Satoshi^*; Koyama Shu; Ueda Yoshihiro; Yamaoka Kazutaka; Sugizaki Mutsumi; Mihara Tatehiro; Matsuoka Masaru; Yoshida Atsumasa; Makishima Kazuo; Ebisawa Ken; Kubota Aya; Yamada Shin' ya; Negoro Hitoshi; Hiroi Kazuo; Ishikawa Masaki; Kawai Nobuyuki; Kimura Masashi; Kitayama Hiroki; Kohama Mitsuhiro; Matsumura Takanori; Morii Mikio; Nakajima Motoki; Serino Motoko; Shidatsu Megumi; Sootome Tetsuya; Sugimori Kousuke; Suwa Fumitoshi; Tomida Hiroshi

来源：Publications of the Astronomical Society of Japan, 2012, 64(1): 13.

DOI：10.1093/pasj/64.1.13

• accretion disks
• black hole physics
• stars: individual (XTE J1752-223)
• X-rays: stars

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 complementarily. 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 similar to 0.7 keV to similar to 0.4 keV and the disk flux decreased by an order of magnitude. Nevertheless, the innermost radius is constant at similar to 41 D-3.5(cos i)(-1/2) km, where D-3.5 is the source distance in units of 3.5 kpc 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-circle dot D-3.5(cos i)(-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 degrees, 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 3.1-55 M-circle dot and 2.3-22 kpc, respectively. This confirms that the compact object in XTE J1752-223 is a black hole.

• 出版日期2012-2-25