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arXiv 1205.4402astro-ph.HE
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Cyg X-3中X射线的能量相关轨道调制和喷流发射的约束

Energy-dependent orbital modulation of X-rays and constraints on emission of the jet in Cyg X-3

Andrzej A. Zdziarski, Chandreyee Maitra, Adam Frankowski, Gerald K. Skinner, Ranjeev Misra

摘要:

我们使用Swift,INTEGRAL和RXTE的数据研究了Cyg X-3 X射线的轨道调制。利用丰富的目前可用的数据和改进的平均方法,我们获得了能量依赖的折叠和平均光变曲线与前所未有的准确性。我们发现,高于~5 keV,调制深度随着能量的增加而减小,这与施主星风中的束缚-自由吸收和康普顿散射引起的调制一致,最小值对应于最高的光学深度,发生在优合附近。我们发现的深度低于3千电子伏,这似乎是由于再发射的软X射线线的风吸收的连续。根据折叠光变曲线的形状,发现Cyg X-3中的喷流的任何X射线贡献(在软光谱态中发射能量>0.1 GeV的伽马射线)在100 keV以下都很小。这意味着存在一个相当尖锐的低能量突破射流兆电子伏范围内的频谱。我们还计算了相位分辨RXTE X射线光谱,并显示对应于周围的优越和低劣的结合相的光谱之间的差异确实可以占在电离介质和康普顿散射中的结合自由吸收的综合效应。

英文摘要:

We study orbital modulation of X-rays from Cyg X-3, using data from Swift, INTEGRAL and RXTE. Using the wealth of the presently available data and an improved averaging method, we obtain energy-dependent folded and averaged light curves with unprecedented accuracy. We find that above ~5 keV, the modulation depth decreases with the increasing energy, which is consistent with the modulation being caused by both bound-free absorption and Compton scattering in the stellar wind of the donor, with minima corresponding to the highest optical depth, which occurs around the superior conjunction. We find a decrease of the depth below ~3 keV, which appears to be due to re-emission of the absorbed continuum by the wind in soft X-ray lines. Based on the shape of the folded light curves, any X-ray contribution from the jet in Cyg X-3, which emits gamma-rays detected at energies >0.1 GeV in soft spectral states, is found to be minor up to ~100 keV. This implies the presence of a rather sharp low-energy break in the jet MeV-range spectrum. We also calculate phase-resolved RXTE X-ray spectra, and show the difference between the spectra corresponding to phases around the superior and inferior conjunctions can indeed be accounted for by a combined effect of bound-free absorption in an ionized medium and Compton scattering.

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