Multi-Frequency VLBA Polarimetry and the Twin-Jet Quasar 0850+581
Multi-Frequency VLBA Polarimetry and the Twin-Jet Quasar 0850+581
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多频 VLBA 旋光仪和双射流 Quasar 0850 581
DOI：
10.3390/galaxies5040092
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Y. Kovalev
中科院分区：
文献类型：
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作者：
E. Kravchenko;Y. Kovalev
利用VLBA方法首次对类星体0850+581进行了多频研究，发现其存在一个双面相对论喷流，喷流的视速度随着与核的分离从3.4c变化到7 c。喷流与反喷流之比约为5，视超光速表明内喷流的观测角度为33 °。由于喷流与周围介质的相互作用，该方向很可能在下游发生显着变化，这一迹象在极化中可见。在这个类星体的最内部区域探测到了一个致密的不均匀的法拉第屏。我们认为，在其核中存在电离气体，这可能是在8.4~GHz频率以下喷流和反喷流中同步辐射的自由-自由吸收的原因。该实验利用随时间缓慢变化的仪器偏振因子（偏振泄漏或D项）。我们报告应用“D-项连接”技术校准VLBA在4.6，5.0，8.1，8.4，15.4，22.3和43.3 GHz频段观测到的电矢量位置角（EVPA）的绝对方向在2007- 2011年。
We present the first multi-frequency VLBA study of the quasar 0850+581 which appears to have a two-sided relativistic jet.Apparent velocity in the approaching jet changes from 3.4c to 7c with the separation from the core. The jet-to-counter-jet ratio of about 5 and apparent superluminal velocities suggest that the observing angle of the inner jet is $\leq33^\circ$. It is likely that this orientation significantly changes downstream due to an interaction of the jet with the surrounding medium, signs of this are seen in polarization. A dense inhomogeneous Faraday screen is detected in the innermost regions of this quasar. We suggest that there is a presence of ionized gas in its nucleus, which might be responsible for the free-free absorption of the synchrotron emission in the jet and counter-jet at frequencies below 8.4~GHz. The experiment makes use of slowly varying instrumental polarisation factors (polarization leakage or D-terms) in time. We report application of the "D-term connection" technique for the calibration of an absolute orientation of electric vector position angle (EVPA) observed by VLBA at 4.6, 5.0, 8.1, 8.4, 15.4, 22.3, and 43.3 GHz bands during the 2007--2011.