FRII射电星系B0925 +420中喷流活动的三幕
Three episodes of jet activity in the FRII radio galaxy B0925+420
摘要：
我们提出了一个“双双射电星系”，一类对象中，两对叶对齐的核两侧的甚大阵列图像。在这个物体B0925+420中，我们发现了第三对波瓣，靠近核心，并且再次与其他波瓣对齐。这是第一个已知的“三双”物体，它极大地增加了这些叶代表喷射活动的多个事件的可能性，而不是底层喷射中的结。我们模拟的叶片在其动态演化。我们发现，内对叶是一致的外部对已被周围介质的位移。中间对叶是更有问题的程度上，一个替代的模型解释的中间和内部的“叶”作为额外的弓冲击外叶内可能更合适，我们讨论了我们的理解的周围介质的密度的影响。
英文摘要：
We present Very Large Array images of a "Double-Double Radio Galaxy", a class of objects in which two pairs of lobes are aligned either side of the nucleus. In this object, B0925+420, we discover a third pair of lobes, close to the core and again in alignment with the other lobes. This first-known "Triple-Double" object strongly increases the likelihood that these lobes represent mutiple episodes of jet activity, as opposed to knots in an underlying jet. We model the lobes in terms of their dynamical evolution. We find that the inner pair of lobes is consistent with the outer pair having been displaced buoyantly by the ambient medium. The middle pair of lobes is more problematic - to the extent where an alternative model interpreting the middle and inner "lobes" as additional bow shocks within the outer lobes may be more appropriate - and we discuss the implications of this on our understanding of the density of the ambient medium.
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