A very rare triple-peaked type-I X-ray burst in the low-mass X-ray binary 4U 1636−53
A very rare triple-peaked type-I X-ray burst in the low-mass X-ray binary 4U 1636−53
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DOI：
10.1111/j.1365-2966.2009.15148.x
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发表时间：
2009-05
影响因子：
4.8
通讯作者：
Guobao Zhang;M. Méndez;D. Altamirano;Tomaso M.Belloni;J. Homan
中科院分区：
文献类型：
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作者：
Guobao Zhang;M. Méndez;D. Altamirano;Tomaso M.Belloni;J. Homan
我们用Rossi X射线计时探测器(RXTE)发现了来自低质量X射线双星(LMXB)4U 1636-53的三峰X射线爆发。这是任何使用RXTE的LMXB报告的第一个三峰爆发，也是从任何来源观测到的第二个此类爆发。(前一次也是来自4U 1636-53，并用EXOSAT观察到的。)从拟合谱到时间分辨谱，我们发现这不是一个半径膨胀的爆发，而且在该爆发的测辐射热光曲线中也出现了在X射线光曲线中看到的相同的三峰模式。类似于以前观察到的这种源的双峰爆发，发射区的半径在爆发期间稳步增加，其间有很短的时间段，在此期间半径基本保持不变。温度先是急剧上升，然后在爆发期间下降，也呈现出三个峰值。温度分布中的第一个和最后一个峰值分别出现在X射线和测辐射热光曲线的第一个和最后一个峰值之前和之后。在这次爆发中，我们没有发现明显的振荡。这一三峰爆发，以及EXOSAT观测到的和该源中的双峰爆发，都发生在4U 1636-53在色彩图中占据相对较窄的区域时，对应于(推断的)相对较高的质量吸积率。目前还没有可用的模型能够解释这种多峰爆发。
We have discovered a triple-peaked X-ray burst from the low-mass X-ray binary (LMXB) 4U 1636-53 with the Rossi X-ray Timing Explorer (RXTE). This is the first triple-peaked burst reported from any LMXB using RXTE, and it is only the second burst of this kind observed from any source. (The previous one was also from 4U 1636-53, and was observed with EXOSAT.) From fits to time-resolved spectra, we find that this is not a radius-expansion burst, and the same triple-peaked pattern seen in the X-ray light curve is also present in the bolometric light curve of the burst. Similar to what was previously observed in double-peaked bursts from this source, the radius of the emitting area increases steadily during the burst, with short periods in between during which the radius remains more or less constant. The temperature first increases steeply, and then decreases across the burst also showing three peaks. The first and last peak in the temperature profile occur, respectively, significantly before and after the first and last peaks in the X-ray and bolometric light curves. We found no significant oscillations during this burst. This triple-peaked burst, as well as the one observed with EXOSAT and the double-peak bursts in this source, all took place when 4U 1636-53 occupied a relatively narrow region in the colour-colour diagram, corresponding to a relatively high (inferred) mass-accretion rate. No model presently available is able to explain the multiple-peaked bursts.