利用核分光望远镜阵列的杂散光研究4U 1700 - 377的可变连续谱和发射线光谱
Studying the Variable Continuum and Emission Line Spectrum of 4U 1700-377 using NuSTAR's Stray Light
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中文总结 AI 辅助
研究4U 1700 - 377的可变连续谱和发射线光谱，通过NuSTAR的聚焦与杂散光观测追踪光谱参数，探讨发射线性质、回旋共振散射特征及低流量状态下连续谱变化，揭示其吸积情况及吸积机制可能变化。
中文摘要 AI 辅助
高质量X射线双星4U 1700 - 377因伴星高度聚集恒星风的吸积作用，在数百秒时间尺度上亮度有强烈变化。利用核分光望远镜阵列（NuSTAR）的两次聚焦观测和五次杂散光观测，扩大了对该源的观测基线并追踪其光谱参数变化。聚焦观测能探测到高于铁Kα能量的多余发射线，但无法独立于模型选择来普遍约束这些线的性质。杂散光数据中普遍存在强烈的铁Kα荧光，但信噪比不足无法进一步测量其他发射线。讨论了杂散光光谱中声称的回旋共振散射特征的统计情况，未找到其存在的确凿证据。最后研究了长达60千秒的持续低流量状态的两个实例，此时光度下降近一个数量级，高能连续谱显著变软且无相应吸收增加，探讨了连续谱形状变化所显示的吸积情况或主导吸积机制的可能变化。
英文摘要
The high-mass X-ray binary 4U 1700-377 shows strong variation in brightness on timescales of hundreds of seconds due to accretion from a highly clumped stellar wind from the companion. Using two focused observations and five stray light observations from NuSTAR, we are able to expand the baseline of observations of the source and track spectral parameters throughout the source's variability. The focused NuSTAR observations confidently detect excess emission lines at energies above Fe K$α$, but are unable to universally constrain the nature of these lines independently of model choice. Strong Fe K$α$ fluorescence is ubiquitous in the stray light data, but these observations lack sufficient signal-to-noise to further measure additional emission lines. We discuss the statistics of a claimed cyclotron resonant scattering feature as seen in the stray light spectra, but find no conclusive evidence for its existence. Finally, we investigate two instances of sustained low-flux states of up to 60 ks. When this occurs, luminosity can fall by almost an order of magnitude and the high-energy continuum softens significantly without corresponding to increased absorption. We discuss the manner in which the changing shape of the continuum during these intervals may show accretion during an extended rarefied interval of stellar wind, or a possible change of the dominant accretion regime.
