理解巨型射电星系J1420-0545：大尺度形态学、环境和能量学
Understanding Giant Radio Galaxy J1420-0545: Large-Scale Morphology, Environment, and Energetics
摘要：
在本文中，我们考虑的可能性，最大的射电星系J1420-0545的结构是由一个重新启动，而不是一个主要的喷流活动。这一假设的动机是不寻常的形态特性的来源，这表明几乎弹道传播的强大的射流在一个特别低密度的环境。对J1420-0545的新射电观测证实了它的形态只有两个狭窄的叶瓣，因此没有发现任何由之前的喷流活动引起的外部低密度空洞的痕迹。使用新获得的无线电数据进行的不同模型拟合暗示了源的相对年轻的年龄，其异常高的膨胀速度，大的喷流动能，并确认了特别低密度的环境。我们发现，它是可能的，以选择一个现实的一组模型参数的假设外叶的J1420-0545是足够老，使其预期的无线电表面亮度大大低于均方根噪声水平的可用的无线电地图。另一方面，J1420-0545瓣周围气体的密度极低，这与宇宙中重子物质的平均密度一致。这表明，源可能位于星系和物质分布的真实空隙中。在这两种情况下，J1420-0545的巨大射电瓣预计将通过驱动强烈的冲击和加热位于银河系分布外围的气体来大幅改变周围的物质。最后，我们还发现，能源的要求是严重的总喷气功率和总能量沉积的流出远离中央发动机。
英文摘要：
In this paper we consider the possibility that the structure of the largest radio galaxy J1420-0545 is formed by a restarted rather than a primary jet activity. This hypothesis is motivated by the unusual morphological properties of the source, suggesting almost ballistic propagation of powerful jets in a particularly low-density environment. New radio observations of J1420-0545 confirm its morphology consisting of only two narrow lobes; no trace of any outer low-density cavity due to the previous jet activity is therefore detected. Different model fits performed using the newly accessed radio data imply relatively young age of the source, its exceptionally high expansion velocity, large jet kinetic power, and confirm particularly low-density environment. We find that it is possible to choose a realistic set of the model parameters for which the hypothetical outer lobes of J1420-0545 are old enough so that their expected radio surface brightness is substantially below the rms noise level of the available radio maps. On the other hand, the extremely low density of the gas surrounding the J1420-0545 lobes is consistent with the mean density of the baryonic matter in the Universe. This suggests that the source may be instead located in a real void of the galaxy and matter distribution. In both cases the giant radio lobes of J1420-0545 are expected to modify substantially the surrounding matter by driving strong shocks and heating the gas located at the outskirts of the filamentary galactic distribution. Finally, we also find that the energetic requirements for the source are severe in terms of the total jet power and the total energy deposited by the outflows far away from the central engine.
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