Photoionization-Driven X-Ray Line Emission in Cygnus X-3
Photoionization-Driven X-Ray Line Emission in Cygnus X-3
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DOI：
10.1086/310217
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发表时间：
1996-09
期刊：
影响因子：
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通讯作者：
D. Liedahl;F. Paerels
中科院分区：
文献类型：
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作者：
D. Liedahl;F. Paerels
X射线双星天鹅座X-3的ASCA-SIS谱在3.5keV附近包含一个窄的类氢硫复合连续谱，这表明X射线发射线区域的温度远低于支撑S15+所需的日冕平衡温度。这一特征的存在立即证实了X射线光致电离在环源介质中产生了极端的过电离，并且X射线发射特征被硬X射线连续体所激发。因此，我们得出结论，天鹅座X-3和其他吸积驱动的X射线源的光谱分析必须在等离子体发射模型的背景下进行，该模型解释了复合主导的布居动力学。此外，复合连续体形状的温度依赖性提供了一种简单的电子温度诊断方法。我们使用为解释复合级联而开发的光谱模型重新分析了SIS数据，并使用这些诊断方法得出了对S15+、Si13+和Mg11+电离区温度的限制条件。
The ASCA SIS spectrum of the X-ray binary Cygnus X-3 is shown to contain a narrow recombination continuum of hydrogenic sulfur near 3.5 keV, which indicates that the temperature of the X-ray emission-line region is far below the coronal equilibrium temperature required to support S15+. The presence of this feature immediately confirms that X-ray photoionization produces extreme overionization in the circumsource medium, and that the X-ray emission features are energized by the hard X-ray continuum. Therefore, we conclude that spectral analyses of Cygnus X-3 and, most likely, other accretion-powered X-ray sources must be conducted in the context of plasma emission models that account for population kinetics dominated by recombination. Furthermore, the temperature dependence of the shapes of recombination continua provides a simple diagnostic of the electron temperature. We reanalyze the SIS data using a spectral model developed to account for recombination cascades, and, using these diagnostics, derive constraints on the temperatures in the S15+, Si13+, and Mg11+ ionization zones.