Effect of non-stationary accretion on spectral state transitions: An example of a persistent neutron star LMXB 4U1636–536
Effect of non-stationary accretion on spectral state transitions: An example of a persistent neutron star LMXB 4U1636–536
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DOI：
10.1088/1674-4527/18/3/33
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发表时间：
2017-12
影响因子：
1.8
通讯作者：
Hui Zhang;Wenfei Yu
中科院分区：
文献类型：
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作者：
Hui Zhang;Wenfei Yu
对黑洞和中子星星X射线双星的观测表明，从硬态到软态跃迁的光度通常高于从软态到硬态跃迁的光度，这表明除了质量吸积率外，还需要其它参数来解释谱态跃迁。在某些黑洞或中子星星的软X射线瞬变过程中，发现对应于硬态到软态跃迁的亮度与下一个软态的峰值亮度正相关。在这项工作中，我们报告的发现相同的相关性，在单一的持久中子星星低质量X射线双星（LMXB）4U 1636-536的基础上的数据，从全天监视器（ASM）的RXTE，气体狭缝相机（GSC）的MAXI和突发警报望远镜（BAT）的斯威夫特。我们还发现，这种正相关持有在这个持久的中子星星LMXB的光度范围跨越约四个因素。我们的研究结果表明，非稳态吸积也起着重要的作用，在驱动X射线光谱状态转变的持续吸积系统与小的吸积耀斑，这是戏剧性得多相比，在许多银河系LMXB瞬变明亮的爆发。
Observations of black hole and neutron star X-ray binaries show that the luminosity of the hard-to-soft state transition is usually higher than that of the soft-to-hard state transition, indicating additional parameters other than mass accretion rate are required to interpret spectral state transitions. It has been found in some individual black hole or neutron star soft X-ray transients that the luminosity corresponding to the hard-to-soft state transition is positively correlated with the peak luminosity of the following soft state. In this work, we report the discovery of the same correlation in the single persistent neutron star low mass X-ray binary (LMXB) 4U 1636–536 based on data from the All Sky Monitor (ASM) on board RXTE, the Gas Slit Camera (GSC) on board MAXI and the Burst Alert Telescope (BAT) on board Swift. We also found such a positive correlation holds in this persistent neutron star LMXB in a luminosity range spanning about a factor of four. Our results indicate that non-stationary accretion also plays an important role in driving X-ray spectral state transitions in persistent accreting systems with small accretion flares, which is much less dramatic compared with the bright outbursts seen in many Galactic LMXB transients.