The Optical Light Curves of XTE J2123–058. III. The Mass of the Binary Components and the Structure of the Quiescent Accretion Disk
The Optical Light Curves of XTE J2123–058. III. The Mass of the Binary Components and the Structure of the Quiescent Accretion Disk
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XTE J2123-058 的光学光曲线 III。二元组分的质量和静态吸积盘的结构。
DOI：
10.1086/346001
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
U. Arizona
中科院分区：
文献类型：
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作者：
T. Shahbaz;C. Zurita;J. Casares;G. Dubus;P. Charles;R. Wagner;E. Ryan;Iac;Caltech;U. Southampton;Large Binocular Telescope Observatory;U. Arizona
本文介绍了1999年和2000年在静止状态下对XTE J2123-058进行的光学测光。我们的R波段光变曲线的主要特征是次级星星的椭球调制;然而，为了令人满意地拟合这一点，我们需要额外的组件，包括一个X射线加热的洛希叶填充次级星星和吸积盘凸起，即，气流撞击吸积盘的地方观测到的0.8相附近的倾角被解释为吸积盘的内部部分被凸起所遮挡。考虑到双星的高倾斜度，这种情况是非常合理的。我们的拟合使我们能够将静态吸积盘的大小限制在（0.26-0.58）RL 1（68%置信度）范围内。利用9.6kpc的距离和从伴星的加热半球推断的X射线通量，我们得到XTE J2123-058在静止时的未吸收X射线光度为1.2 × 1033 ergs-1。从观测到的静态光学/红外颜色，我们发现吸积盘的光谱分布的幂律指数（-1.4）与其他静态X射线瞬态比较好。我们还重新分析了软X射线瞬态XTE J2123-058在1998年爆发和衰变期间拍摄的光学光变曲线。我们使用一个强大的方法来拟合数据，使用一个精致的X射线二元模型。该模型计算了X射线照射下充满罗氏瓣的星星和耀斑吸积盘产生的光，并计算了阴影和相互星星/盘食的影响。我们得到相对准确的值的二进制的倾角和质量比，当结合在纸II中得到的光谱结果，给出了中子星星质量在1.04-1.56 M的范围内（68%的信心）。
We present optical photometry of XTE J2123-058 taken in 1999 and 2000, during its quiescent state. The dominant feature of our R-band light curve is the ellipsoidal modulation of the secondary star; however, in order to fit this satisfactorily, we require additional components that comprise an X-ray-heated Roche lobe-filling secondary star and an accretion disk bulge, i.e., where the gas stream impacts the accretion disk. The observed dip near phase 0.8 is interpreted as the eclipse of inner parts of the accretion disk by the bulge. This scenario is highly plausible given the high binary inclination. Our fits allow us to constrain the size of the quiescent accretion disk to lie in the range (0.26-0.58)RL1 (68% confidence). Using the distance of 9.6 kpc and the X-ray flux inferred from the heated hemisphere of the companion, we obtain an unabsorbed X-ray luminosity of 1.2 × 1033 ergs s-1 for XTE J2123-058 in quiescence. From the observed quiescent optical/IR colors, we find that the power-law index (-1.4) for the spectral distribution of the accretion disk compares well with other quiescent X-ray transients. We also reanalyze the optical light curves of the soft X-ray transient XTE J2123-058 taken during its outburst and decay in 1998. We use a robust method to fit the data using a refined X-ray binary model. The model computes the light arising from a Roche lobe-filling star and flared accretion disk irradiated by X-rays and calculates the effects of shadowing and mutual star/disk eclipses. We obtain relatively accurate values for the binary inclination and mass ratio, which when combined with spectroscopic results obtained in Paper II, gives a neutron star mass in the range 1.04-1.56 M☉ (68% confidence).