Hongmin Cao, Jun Yang, Sándor Frey, Callan M. Wood, James C. A. Miller-Jones, Krisztina É. Gabányi, Giulia Migliori, Marcello Giroletti, Lang Cui, Tao An, Xiaoyu Hong and WeiHua Wang
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引用次数: 0
Abstract
We observed a newly discovered Galactic black hole X-ray binary Swift J1727.8–1613 with the European VLBI Network (EVN) at 5 GHz. The observation was conducted immediately following a radio quenching event detected by the Karl G. Jansky Very Large Array. The visibility amplitude evolution over time reveals a large-amplitude radio flare and is consistent with an ejection event. The data can be interpreted either as a stationary component (i.e., the radio core) and a moving blob, or as two blobs moving away from the core symmetrically in opposite directions. The initial angular separation speed of the two components was estimated to 30 mas day−1. We respectively fitted a single circular Gaussian model component to each of 14 sliced visibility data sets. For the case of including only European baselines, during the final hour of the EVN observation, the fitted sizes exhibited linear expansion, indicating that the measured sizes were dominated by the angular separation of the two components. The 6 hr EVN observation took place in a rising phase of an even larger 4 day long radio flare, implying that the ejection events were quite frequent and therefore continuous radio monitoring is necessary to correctly estimate the power of the transient jet. Combined with X-ray monitoring data, the radio quenching and subsequent flares/ejections were likely driven by instabilities in the inner hot accretion disk.
我们利用欧洲VLBI网络(EVN)在5 GHz波段观测了新发现的银河系黑洞x射线双星Swift J1727.8-1613。这次观测是在卡尔·g·杨斯基甚大阵列探测到射电猝灭事件后立即进行的。可见振幅随时间的演变揭示了一个大振幅的射电耀斑,与抛射事件相一致。数据可以被解释为一个固定的组件(即,无线电核心)和一个移动的斑点,或者两个斑点以相反的方向对称地远离核心。两组分的初始角分离速度估计为30 mas day−1。我们分别将单个圆形高斯模型组件拟合到14个切片可见性数据集中的每个数据集。对于仅包括欧洲基线的情况,在EVN观测的最后一个小时内,拟合尺寸呈现线性膨胀,表明测量尺寸主要由两个分量的角分离决定。6小时的EVN观测发生在一个更大的持续4天的射电耀斑的上升阶段,这意味着抛射事件相当频繁,因此连续的射电监测是必要的,以正确估计瞬态喷射的功率。结合x射线监测数据,无线电猝灭和随后的耀斑/喷射可能是由内部热吸积盘的不稳定性驱动的。