QUASI-PERIODIC OSCILLATIONS IN SHORT RECURRING BURSTS OF MAGNETARS SGR 1806−20 AND SGR 1900+14 OBSERVED WITH RXTE
QUASI-PERIODIC OSCILLATIONS IN SHORT RECURRING BURSTS OF MAGNETARS SGR 1806−20 AND SGR 1900+14 OBSERVED WITH RXTE
复制标题
用 RXTE 观测到的 SGR 1806−20 和 SGR 1900+14 磁体短时重复爆发中的准周期振荡
DOI：
10.1088/0004-637x/795/2/114
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
E. Göğüş
中科院分区：
文献类型：
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作者：
D. Huppenkothen;L. Heil;A. Watts;E. Göğüş
在磁星的巨大耀斑中观察到的准周期振荡（QPO）特别令人感兴趣，因为它们有可能通过中子星星星震学打开一扇通往中子星星内部的窗口。然而，只有三个巨大的耀斑被观察到。因此，我们利用更大的数据集的较短，能量较低的经常性爆发。在这里，我们报告的搜索QPO在一个大的数据集的爆发，从两个最活跃的磁星，SGR 1806-20和SGR 1900+14，观察罗西X射线定时探测器。我们在SGR 1806−20的平均周期图中发现了一个单一的探测，该周期图包括30个爆发，频率为57 Hz，宽度为5 Hz，与SGR 1900+14观测到的巨大耀斑QPO非常相似。这个QPO自然适合在全球磁弹性扭转振荡的框架内解释巨型耀斑QPO。此外，我们发现了傅立叶分析的光变曲线的适用性与低背景计数率和短时间尺度上的强变异性的限制。在这种情况下，标准傅立叶方法和更复杂的傅立叶分析由于产生不可接受的大量假阳性检测而同等程度地失败。这个问题在傅立叶域中并不容易解决。相反，我们展示了光变曲线的模拟如何为这些光变曲线中的QPO搜索提供可行的解决方案。
Quasi-periodic oscillations (QPOs) observed in the giant flares of magnetars are of particular interest due to their potential to open up a window into the neutron star interior via neutron star asteroseismology. However, only three giant flares have been observed. We therefore make use of the much larger data set of shorter, less energetic recurrent bursts. Here, we report on a search for QPOs in a large data set of bursts from the two most burst-active magnetars, SGR 1806–20 and SGR 1900+14, observed with Rossi X-ray Timing Explorer. We find a single detection in an averaged periodogram comprising 30 bursts from SGR 1806−20, with a frequency of 57 Hz and a width of 5 Hz, remarkably similar to a giant flare QPO observed from SGR 1900+14. This QPO fits naturally within the framework of global magneto-elastic torsional oscillations employed to explain giant flare QPOs. Additionally, we uncover a limit on the applicability of Fourier analysis for light curves with low background count rates and strong variability on short timescales. In this regime, standard Fourier methodology and more sophisticated Fourier analyses fail in equal parts by yielding an unacceptably large number of false-positive detections. This problem is not straightforward to solve in the Fourier domain. Instead, we show how simulations of light curves can offer a viable solution for QPO searches in these light curves.