On the Correlated X-Ray and Optical Evolution of SS Cygni
On the Correlated X-Ray and Optical Evolution of SS Cygni
复制标题
关于天鹅座SS的相关X射线和光学演化
DOI：
--
复制
发表时间：
2002
期刊：
影响因子：
--
通讯作者：
S. Trudolyubov
中科院分区：
文献类型：
--
作者：
K. McGowan;W. Priedhorsky;S. Trudolyubov
我们利用RXTE数据和AAVSO观测资料分析了原型矮新星系统SS-Cygni的变率和光谱演化。一系列有针对性的RXTE/PCA观测使我们能够以前所未有的细节追踪天鹅座SS的X射线光谱的演变，而6年的光学AAVSO和RXTE/ASM光曲线则显示出长期的模式。我们采用了一种将X射线通量叠加在多个爆发上的技术，根据光学光曲线的阶段性，我们研究了爆发的形态。我们发现，3-12keV的X射线通量在光学爆发期间受到抑制，这种行为以前曾见过，但只在少数几个周期中出现。用更灵敏的RXTE/PCA观测到的几次SS天鹅座爆发也表明了光学爆发过程中X射线的抑制。我们量化了光学爆发和X射线爆发之间的时间滞后，以及从爆发中恢复X射线的时间尺度。SS天鹅座流星的光学特性曲线显示出短暂的异常爆发。在这些事件期间，硬X射线和光通量一起增加。长期数据表明，X射线在两次爆发之间会下降。我们的结果与修正的盘不稳定性模型基本一致，修正的盘不稳定性模型提出了一种双组分吸积流，该吸积流由内径截断的冷光学厚吸积盘和延伸到白矮星表面的类球形热晕状流组成。我们在Meyer&Meyer-Hofmeister提出的一个包含光学厚度吸积盘内部蒸发的模型框架下讨论了我们的结果。
We have analyzed the variability and spectral evolution of the prototype dwarf nova system SS Cygni using RXTE data and AAVSO observations. A series of pointed RXTE/PCA observations allow us to trace the evolution of the X-ray spectrum of SS Cygni in unprecedented detail, while 6 years of optical AAVSO and RXTE/ASM light curves show long-term patterns. Employing a technique in which we stack the X-ray flux over multiple outbursts, phased according to the optical light curve, we investigate the outburst morphology. We find that the 3-12 keV X-ray flux is suppressed during optical outbursts, a behavior seen previously but only in a handful of cycles. The several outbursts of SS Cygni observed with the more sensitive RXTE/PCA also show a depression of the X-rays during optical outburst. We quantify the time lags between the optical and X-ray outbursts and the timescales of the X-ray recovery from outburst. The optical light curve of SS Cygni exhibits brief anomalous outbursts. During these events the hard X-rays and optical flux increase together. The long-term data suggest that the X-rays decline between outbursts. Our results are in general agreement with modified disk instability models, which invoke a two-component accretion flow consisting of a cool optically thick accretion disk truncated at an inner radius, and a quasi-spherical hot corona-like flow extending to the surface of the white dwarf. We discuss our results in the framework of one such model, involving the evaporation of the inner part of the optically thick accretion disk, proposed by Meyer & Meyer-Hofmeister.