We have analyzed archival Very Long Baseline Array (VLBA) data for Cygnus A between 2002 and 2013, to search for radio emission from the transient discovered in 2015 by Perley et al. approximately 0.″4 from the nucleus of Cygnus A (Cyg A-2). Perley et al. use Very Large Array and VLBA archival data (between 1989 and 1997) to show that the transient rises in flux density by a factor of at least 5 in less than approximately 20 yr. With the additional data presented here, we revise the rise time to between approximately 4 and 6 yr, based on a new detection of the source at 15.4 GHz from 2011 October. Our results strengthen the interpretation of Cyg A-2 as the result of a tidal disruption event (TDE), as we can identify the location of the compact object responsible for the TDE and can estimate the angular expansion speed of the resulting radio-emitting structures, equivalent to an apparent expansion speed of <0.9 c . While our results are consistent with recent X-ray analys...

中文翻译：

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天鹅座A核电瞬变（Cyg A-2）的档案VLBA观测加强了潮汐干扰事件的解释。

我们分析了2002年至2013年间天鹅座A的档案超长基线阵列（VLBA）数据，以搜索Perley等人在2015年发现的瞬变中的无线电发射。大约从天鹅座A（Cyg A-2）的核起0.“ 4。Perley等。使用甚大阵列和VLBA档案数据（1989年至1997年）显示，在不到20年的时间内，瞬态通量密度至少增加了5倍。根据此处提供的其他数据，我们根据2011年10月以来对15.4 GHz频率源的新发现，将上升时间修改为大约4至6年。我们的结果加强了潮汐破坏事件（TDE）对Cyg A-2的解释，因为我们可以识别出负责TDE的紧凑物体的位置，并且可以估计所得无线电发射结构的角膨胀速度，等效于<0.9 c的表观膨胀速度。虽然我们的结果与最近的X射线分析相符...