NuSTAR view of the Z-type neutron star low-mass X-ray binary Cygnus X-2
NuSTAR view of the Z-type neutron star low-mass X-ray binary Cygnus X-2
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Z 型中子星低质量 X 射线双星天鹅座 X-2 的 NuSTAR 视图
DOI：
10.1093/mnras/stx2931
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发表时间：
2017
影响因子：
4.8
通讯作者：
B. Raychaudhuri
中科院分区：
文献类型：
--
作者：
A. Mondal;G. Dewangan;M. Pahari;B. Raychaudhuri
我们报告了2015年1月7日进行的Z型中子星星低质量X射线双星天鹅座X-2的\努斯塔{}观测。在此观察期间，源表现出计数率（下降）的突然下降和更强的可变性在$3 - 79\kev $X射线光曲线。硬度-强度图显示，尽管在下降期间观察到扩展的\quotes\flaring branch，但源仍保持在Z轨迹的所谓\quotes\normal branch中。该光源处于软光谱状态，其$3 - 45\kev $亮度为$L\simeq（0.5 - 1.1）\times 10 ^{38}$erg s $^{-1}$，假设距离为8 kpc。无论是非倾角和倾角X-射线光谱都很好地代表了模型，其中软带主要由光盘的发射，而硬X-射线带主要由康普顿发射从边界层/日冕和它的反射发射从光盘。的X射线光谱还揭示了一个广泛的Fe K $\alpha $发射线，这是几乎对称的较高的通量和不对称的通量时，减少了一个因素的$\sim 2 $。相对论反射模型预测吸积盘的内半径为：非倾斜态为$R_{in}\simeq2.5 - 6.0\：R_{ISCO}\：（\simeq30 - 73 $Km），倾斜态为$R_{in}\simeq2.0 - 2.6\：R_{ISCO}\：（\simeq24 - 32 $Km）.如果内盘由于磁场产生的压力而被截断，这意味着磁极处的磁场强度上限为7.6G，这与其他估计值一致。
We report on the \nustar{} observation of the Z-type neutron star low-mass X-ray binary Cygnus X--2 performed on 7 January 2015. During this observation, the source exhibited sudden decrease in count rate (dips) and stronger variability in $3-79\kev$ X-ray lightcurve. The hardness-intensity diagram shows that the source remained in the so-called \quotes{normal branch} of the Z-track, although an extended \quotes{flaring branch} is observed during the dips. The source was in a soft spectral state with the $3-45\kev$ luminosity of $L\simeq(0.5-1.1)\times 10^{38}$ erg s$^{-1}$, assuming a distance of 8 kpc. Both the non-dip and dip X-ray spectra are well represented by models in which the soft band is dominated by the emission from the disc, while the hard X-ray band is dominated by the Comptonized emission from the boundary layer/corona and its reflected emission from the disc. The X-ray spectrum also revealed a broad Fe K$\alpha$ emission line which is nearly symmetric at the higher flux and asymmetric when the flux is reduced by a factor of $\sim 2$. The relativistic reflection model predicts the inner radius of the accretion disc as $R_{in}\simeq2.5-6.0\:R_{ISCO}\:(\simeq30-73$ Km) for the non-dip state and $R_{in}\simeq2.0-2.6\:R_{ISCO}\:(\simeq24-32$ Km) for the dip state. If the inner disc is truncated due to the pressure arising from a magnetic field, this implies an upper limit of the magnetic field strength of $\leq7.6\times10^{9}$ G at the magnetic poles which is consistent with other estimates.
使用 NuSTAR 对 SERPENS X-1 中子星和内吸积流的约束
DOI：
10.1088/2041-8205/779/1/l2
发表时间：
2013
期刊：
The Astrophysical Journal
影响因子：
--
作者：
Miller J
通讯作者：
Miller J
DOI：
10.1088/0004-637x/720/1/205
发表时间：
2009-08
期刊：
The Astrophysical Journal
影响因子：
--
作者：
E. Cackett
通讯作者：
E. Cackett