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arXiv 1105.3586astro-ph.HE
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用Suzaku和IRSF对GX 339-4低/硬态的X射线和近红外观测

X-Ray and Near-Infrared Observations of GX 339-4 in the Low/Hard State with Suzaku and IRSF

Megumi Shidatsu, Yoshihiro Ueda, Fumie Tazaki, Tatsuhito Yoshikawa, Takahiro Nagayama, Tetsuya Nagata, Nagisa Oi, Kazutaka Yamaoka, Hiromitsu Takahashi, Aya Kub… 展开作者

Megumi Shidatsu, Yoshihiro Ueda, Fumie Tazaki, Tatsuhito Yoshikawa, Takahiro Nagayama, Tetsuya Nagata, Nagisa Oi, Kazutaka Yamaoka, Hiromitsu Takahashi, Aya Kubota, Jean Cottam, Ronald Remillard, Hitoshi Negoro

摘要:

2009年3月,朱雀和IRSF对银河系黑洞双星GX 339- 4进行了X射线和近红外($J$-$H$ - $K_{\rm s}$)观测。在0.5- 300 keV波段的光谱主要是热康普顿化的盘光子,从直接盘组件的一个小的贡献,表明内部盘几乎完全覆盖的热日冕的电子温度为$\approx$ 175 keV。康普顿化日冕至少有两个光学深度$τ\approx 1,0.4$。对铁-K线轮廓的分析得出内盘半径为$(13.3^{+6.4}_{-6.0}) R_{\rm g}$($R_{\rm g} $代表引力半径$GM/c^2$),最佳拟合倾角为$\approx50^\circ$。这个半径与假设康普顿化中光子数守恒的连续拟合估计的半径一致。我们的结果表明,GX 339- 4的标准盘可能在到达最里面的稳定圆形轨道(对于非旋转黑洞)之前被截断,在$\sim$ 1%的爱丁顿光度的低/硬态。用$F_{\rm Ks} \propto F_{\rm X}^{0.45}$对硬X射线通量与一天平均的近红外光变曲线进行了关联。近红外$νF_ν$光谱比射电光谱更平坦,表明来自致密喷流的光学薄同步辐射主导了近红外通量。基于简单的分析,我们估计喷流底部的磁场和尺寸分别为$5\times10^4$ G和$6\times 10^8$ cm。同步加速器自康普顿分量估计约占总X射线通量的0.4%。

英文摘要:

X-ray and near-infrared ($J$-$H$-$K_{\rm s}$) observations of the Galactic black hole binary GX 339--4 in the low/hard state were performed with Suzaku and IRSF in 2009 March. The spectrum in the 0.5--300 keV band is dominated by thermal Comptonization of multicolor disk photons, with a small contribution from a direct disk component, indicating that the inner disk is almost fully covered by hot corona with an electron temperature of $\approx$175 keV. The Comptonizing corona has at least two optical depths, $τ\approx 1,0.4$. Analysis of the iron-K line profile yields an inner disk radius of $(13.3^{+6.4}_{-6.0}) R_{\rm g}$ ($R_{\rm g} $ represents the gravitational radius $GM/c^2$), with the best-fit inclination angle of $\approx50^\circ$. This radius is consistent with that estimated from the continuum fit by assuming the conservation of photon numbers in Comptonization. Our results suggest that the standard disk of GX 339--4 is likely truncated before reaching the innermost stable circular orbit (for a non rotating black hole) in the low/hard state at $\sim$1% of the Eddington luminosity. The one-day averaged near-infrared light curves are found to be correlated with hard X-ray flux with $F_{\rm Ks} \propto F_{\rm X}^{0.45}$. The flatter near infrared $νF_ν$ spectrum than the radio one suggests that the optically thin synchrotron radiation from the compact jets dominates the near-infrared flux. Based on a simple analysis, we estimate the magnetic field and size of the jet base to be $5\times10^4$ G and $6\times 10^8$ cm, respectively. The synchrotron self Compton component is estimated to be approximately 0.4% of the total X-ray flux.

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