Discovery of 800 Hz Quasi-periodic Oscillations in 4U 1608–52
Discovery of 800 Hz Quasi-periodic Oscillations in 4U 1608–52
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DOI：
10.1086/310256
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发表时间：
1996-09
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影响因子：
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通讯作者：
M. Berger;M. van der Klis;J. van Paradijs;W. Lewin;F. Lamb;B. Vaughan;E. Kuulkers;T. Augusteijn;W. Zhang;Fiona Marshall;J. Swank;I. Lapidus;J. Lochner;T. Strohmayer
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文献类型：
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作者：
M. Berger;M. van der Klis;J. van Paradijs;W. Lewin;F. Lamb;B. Vaughan;E. Kuulkers;T. Augusteijn;W. Zhang;Fiona Marshall;J. Swank;I. Lapidus;J. Lochner;T. Strohmayer
我们介绍了罗西x射线计时探测器在1996年3月x射线强度爆发下降期间对低质量x射线双星和环礁源4U 1608-52的9天观测结果。快速时序分析显示，3月3日和6日在850 ~ 890hz频率处出现了一个强而窄的准周期振荡峰，3月9日在690hz频率附近出现了一个宽的准周期振荡峰。3月12日的观测没有显示出明显的信号。3月3日，QPO的x射线光谱相当硬；强度从~2 keV时的5%稳步提高到~12 keV时的20%。当天的QPO频率在850 ~ 890hz之间变化，随着质心频率的增加，峰值变宽，有效值减小，其方式与Z源中众所周知的水平分支振荡（HBO）非常相似。我们将HBO拍频模型应用于环礁源，结果表明，尽管该模型可以在观测到的频率下产生QPO，但我们观察到的QPO性质与x射线计数率之间缺乏相关性，这很难与该模型相一致。
We present results of Rossi X-Ray Timing Explorer observations of the low-mass X-ray binary and atoll source 4U 1608-52 made over 9 days during the decline of an X-ray intensity outburst in 1996 March. A fast-timing analysis shows a strong and narrow quasi-periodic oscillation (QPO) peak at frequencies between 850 and 890 Hz on March 3 and 6, as well as a broad peak around 690 Hz on March 9. Observations on March 12 show no significant signal. On March 3, the X-ray spectrum of the QPO is quite hard; its strength increases steadily from 5% at ~2 keV to ~20% at ~12 keV. The QPO frequency varies between 850 and 890 Hz on that day, and the peak widens and its rms decreases with centroid frequency in a way very similar to the well-known horizontal branch oscillations (HBO) in Z sources. We apply the HBO beat frequency model to atoll sources and suggest that, whereas the model could produce QPOs at the observed frequencies, the lack of correlation we observe between QPO properties and X-ray count rate is hard to reconcile with this model.