Characterizing the quiescent X-ray variability of the black hole low-mass X-ray binary V404 Cyg
Characterizing the quiescent X-ray variability of the black hole low-mass X-ray binary V404 Cyg
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DOI：
10.1093/mnras/stu140
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发表时间：
2014-01
影响因子：
4.8
通讯作者：
F. Bernardini;E. Cackett
中科院分区：
文献类型：
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作者：
F. Bernardini;E. Cackett
我们对黑洞低质量X射线双星V404 Cyg进行了第一次长期（75天）X射线监测，目的是了解和表征其在静止期间的变化。V404的X射线光变曲线显示了几个小时时间尺度的耀斑，计数率变化约为5-8倍。均方根变异性为Fvar = 57.0（3.2）%。一阶结构函数与指数-1的功率谱（闪烁噪声）或指数0的功率谱（白色噪声）一致，这意味着光曲线在从几天到几个月的时间尺度上是可变的。X射线谱符合幂律，谱指数{\Gamma} = 2.10 - 2.35，我们发现，随着通量的变化，谱的形状大致保持不变。相对于X射线通量的变化，恒定的光谱形状可能有利于X射线发射由射流中产生的同步辐射主导的情况。
We conducted the first long-term (75 days) X-ray monitoring of the black hole low mass X-ray binary V404 Cyg, with the goal of understanding and characterizing its variability during quiescence. The X-ray light curve of V404 shows several flares on timescales of hours with a count rate change of a factor of about 5-8. The root mean square variability is Fvar = 57.0(3.2) percent. The first order structure function is consistent with both a power spectrum of index -1 (flicker noise), or with a power spectrum of index 0 (white noise), implying that the light curve is variable on timescales from days to months. The X-ray spectrum is well fitted by a power law with spectral index {\Gamma} = 2.10 - 2.35, and we found that the spectral shape remains roughly constant as the flux changes. A constant spectral shape with respect to a change in the X-ray flux may favour a scenario in which the X-ray emission is dominated by synchrotron radiation produced in a jet.