A decade of radio imaging the relativistic outflow in the peculiar X-ray binary Circinus X-1
A decade of radio imaging the relativistic outflow in the peculiar X-ray binary Circinus X-1
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十年来对奇特 X 射线双星圆规座 X-1 中的相对论性外流进行射电成像
DOI：
10.1111/j.1365-2966.2008.13788.x
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发表时间：
2008
影响因子：
4.8
通讯作者：
Manchester
中科院分区：
文献类型：
--
作者：
V. Tudose;R. Fender;A. Tzioumis;R. Spencer;M. V. D. K. Amsterdam;Bucharest;Southampton;Atnf;Manchester
我们展示了澳大利亚紧凑型望远镜阵列在 4.8 和 8.6 GHz 频率下在近 10 年的时间间隔内对中子星 X 射线双星和相对论射流源 Circinus X-1 进行的观测。该系统显示出射电特征在从几天到几年的所有时间尺度上的形态和亮度的显着变化。利用射电发射不同成分的连续变亮之间的时间延迟，我们能够为角秒尺度流出的相对论性质提供进一步的证据，表观速度 beta(app) >= 12。没有发现射流轴方向演变的令人信服的证据。我们还对系统自行设定了上限，这与之前的光学研究一致。除了之前报道的接近轨道相位 0.0 的射电耀斑（解释为近星体通道时的吸积增强）之外，我们还发现了轨道相位 0.5 附近具有类似特性的爆发。全局光谱指数显示在整个监测期间优先出现陡峭光谱，平均值和标准差 α = -0.9 +/- 0.6（F-nu 与 nu(α) 成比例），在爆发期间变得明显平坦。在三分之一的历元中检测到偏振，并且在一种情况下测量了靠近系统核心的法拉第旋转。
We present observations of the neutron star X-ray binary and relativistic jet source Circinus X-1 made at 4.8 and 8.6 GHz with the Australia Telescope Compact Array during a time interval of almost 10 yr. The system shows significant variations in the morphology and brightness of the radio features on all time-scales from days to years. Using the time delay between the successive brightening of the different components of the radio emission we were able to provide further evidence for the relativistic nature of the arcsec-scale outflow, with an apparent velocity beta(app) >= 12. No compelling evidence for an evolution of the orientation of the jet axis was found. We also place an upper limit on the proper motion of the system which is consistent with previous optical studies. Besides the previously reported radio flares close to the orbital phase 0.0 (interpreted as enhanced accretion at periastron passage), we identified outbursts with similar properties near the orbital phase 0.5. The global spectral index revealed a preferentially steep spectrum over the entire period of monitoring with a mean value and standard deviation alpha = -0.9 +/- 0.6(F-nu proportional to nu(alpha)), which became significantly flatter during the outbursts. Polarization was detected in one third of the epochs, and in one case Faraday rotation close to the core of the system was measured.