A Nonthermal Radio Filament Connected to the Galactic Black Hole?
A Nonthermal Radio Filament Connected to the Galactic Black Hole?
复制标题
连接到银河黑洞的非热射电丝？
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
W. Goss
中科院分区：
文献类型：
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作者：
M. Morris;Jun;W. Goss
利用甚大阵列，我们研究了最近在银河系黑洞及其射电对应物SgrA*附近发现的一个非热射电灯丝(NTF)。虽然这个NTF--SgrA西丝(SgrAWF)--与占据银河系中心数百秒的NTF有许多共同的特征，但SgrAWF的不同之处在于它的方位和天空位置表明它与SgrA*有密切的物理联系。我们展示了使用创新方法构建的3.3和5.5厘米图像，该方法产生了非常高的动态范围，提供了史无前例的SgrAWF清晰图像。虽然SgrAWF与SgrA*的物理联系并不明确，但这些图像无疑唤起了这种有趣的可能性。假设SgrAWF与SgrA*有物理关系，我们将研究其潜在的影响。其一是SgrA*是相对论粒子源，它被约束为沿着有序的局部场线扩散。相对论粒子也可以通过SgrA*的准直流出进入局域场，可能是在磁场穿过视界的情况下，伴随着黑洞自转的Poynting磁通驱动的。其次，我们考虑了SgrAWF是锚定在黑洞上的低质量密度宇宙弦的表现形式的可能性。这些假设的最简单形式是预测暗条是双向的，而SgrAWF只出现在SgrA*的一侧，这可能是因为局部介质的动力学。
Using the Very Large Array, we have investigated a nonthermal radio filament (NTF) recently found very near the Galactic black hole and its radio counterpart, Sgr A*. While this NTF—the Sgr A West Filament (SgrAWF)—shares many characteristics with the population of NTFs occupying the central few hundred parsecs of the Galaxy, the SgrAWF has the distinction of having an orientation and sky location that suggest an intimate physical connection to Sgr A*. We present 3.3 and 5.5 cm images constructed using an innovative methodology that yields a very high dynamic range, providing an unprecedentedly clear picture of the SgrAWF. While the physical association of the SgrAWF with Sgr A* is not unambiguous, the images decidedly evoke this interesting possibility. Assuming that the SgrAWF bears a physical relationship to Sgr A*, we examine the potential implications. One is that Sgr A* is a source of relativistic particles constrained to diffuse along ordered local field lines. The relativistic particles could also be fed into the local field by a collimated outflow from Sgr A*, perhaps driven by the Poynting flux accompanying the black hole spin in the presence of a magnetic field threading the event horizon. Second, we consider the possibility that the SgrAWF is the manifestation of a low-mass-density cosmic string that has become anchored to the black hole. The simplest form of these hypotheses would predict that the filament be bi-directional, whereas the SgrAWF is only seen on one side of Sgr A*, perhaps because of the dynamics of the local medium.