X-ray variability patterns and radio/X-ray correlations in Cyg X-1
X-ray variability patterns and radio/X-ray correlations in Cyg X-1
复制标题
DOI：
10.1111/j.1365-2966.2011.19127.x
复制
发表时间：
2011-03
影响因子：
4.8
通讯作者：
A. Zdziarski;G. Skinner;G. Pooley;P. Lubiński
中科院分区：
文献类型：
--
作者：
A. Zdziarski;G. Skinner;G. Pooley;P. Lubiński
利用Rossi X射线定时探测器上的全天监视器、康普顿伽马射线天文台上的爆发和瞬态源实验以及Swift上的爆发警报望远镜的X射线数据，研究了天鹅座X-1所有光谱状态下的X射线变率模式以及射电和X射线通量的相关性。在硬态，占主导地位的光谱变异性是一个固定的光谱形状的归一化的变化，而在中间状态，斜率的变化，与枢轴点约10千电子伏。在软态，低能量的X射线辐射占主导地位的辐射热通量是松散的相关性与高能量的发射。在硬态的黑洞双星中，射电通量通常取决于X射线通量的幂，FR <$FpX。我们确认这是Cyg X-1。我们的新发现是，这种相关性延伸到中间和软状态，提供宽带X射线通量的康普顿化部分的频谱（不包括黑体组件）被认为是一个窄带中等能量的X射线通量。我们发现15 GHz无线电发射的指数p 1.7 ± 0.1，在2.25 GHz时下降至p 1.5 ± 0.1。我们的结论是，在15 GHz的较高的值是由于在风中的自由-自由吸收的同伴的效果。内在相关指数仍不确定。然而，根据天鹅X-1风的理论模型，它可能接近1.3，这在吸积/喷流模型的框架内，意味着天鹅X-1的吸积流是辐射有效的。与康普顿化辐射通量的相关表明，在天鹅座X-1的所有光谱态中，射电喷流都是由吸积流中的热电子发射的。另一方面，我们能够排除X射线射流模型。最后，我们发现，指数的相关性，在一个狭窄的能带测量时，使用X射线通量，强烈地依赖于所选择的频带，并且是，在一般情况下，不同的热电子发射中的热辐射通量或通量。
We have studied the X-ray variability patterns and correlations of the radio and X-ray fluxes in all spectral states of Cyg X-1 using X-ray data from the All-Sky Monitor onboard the Rossi X-ray Timing Explorer, Burst And Transient Source Experiment onboard the Compton Gamma Ray Observatory and the Burst Alert Telescope onboard Swift. In the hard state, the dominant spectral variability is a changing of normalization with a fixed spectral shape, while in the intermediate state, the slope changes, with a pivot point around 10 keV. In the soft state, the low-energy X-ray emission dominates the bolometric flux which is only loosely correlated with the high-energy emission. In black hole binaries in the hard state, the radio flux is generally found to depend on a power of the X-ray flux, FR∝FpX. We confirm this for Cyg X-1. Our new finding is that this correlation extends to the intermediate and soft states, provided the broad-band X-ray flux in the Comptonization part of the spectrum (excluding the blackbody component) is considered instead of a narrow-band medium-energy X-ray flux. We find an index p≃ 1.7 ± 0.1 for 15-GHz radio emission, decreasing to p≃ 1.5 ± 0.1 at 2.25 GHz. We conclude that the higher value at 15 GHz is due to the effect of free–free absorption in the wind from the companion. The intrinsic correlation index remains uncertain. However, based on a theoretical model of the wind in Cyg X-1, it may to be close to ≃1.3, which, in the framework of accretion/jet models, would imply that the accretion flow in Cyg X-1 is radiatively efficient. The correlation with the flux due to Comptonization emission indicates that the radio jet is launched by the hot electrons in the accretion flow in all spectral states of Cyg X-1. On the other hand, we are able to rule out the X-ray jet model. Finally, we find that the index of the correlation, when measured using the X-ray flux in a narrow energy band, strongly depends on the band chosen and is, in general, different from that for either the bolometric flux or the flux in the hot-electron emission.