论文标题
低亮度星系中超质量黑洞附近的磁场结构：SGR A*的情况
Magnetic field structure in the vicinity of a super-massive black hole in low luminosity galaxies: the case of Sgr A*
论文作者
论文摘要
$ \ rm sgra^*$的观察为低亮度积聚提供了很多见解，少数明亮的耀斑伴随着靠近地平线的轨道运动。有人提出，天然气供应来自超级黑洞附近的恒星风。我们在这里认为，黑洞附近的流量具有低磁化强度和交替的极性结构，完全由所研究且长期以来的MRI湍流过程决定。可以这种情况，只要距黑洞磁扩散率更大，因此磁场将永远不会达到均值值。对于$ \ rm sgra^*$，我们显示了该特定磁场几何形状的直接后果，该几何形状是：（i）从静态状态到耀斑活动的间歇性流动，（ii）不可能进行磁性固定的配置。此外，这种几何形状的另一个独特特征是强烈的磁重新连接事件，在黑洞附近积聚了相反的磁极性层。最后，我们认为在这种情况下缺少喷气结构将是43 \＆86 GHz观察中的吸烟枪。
Observations of $\rm SgrA^*$ have provided a lot of insight on low-luminosity accretion, with a handful of bright flares accompanied with orbital motion close to the horizon. It has been proposed that gas supply comes from stellar winds in the neighborhood of the supermassive black hole. We here argue that the flow at the vicinity of the black hole has a low magnetization and a structure of alternating polarity totally dictated by the well studied and long-ago proposed MRI turbulent process. This can be the case, provided that in larger distances from the black hole magnetic diffusivity is dominant and thus the magnetic field will never reach equipartition values. For $\rm SgrA^*$, we show the immediate consequences of this specific magnetic field geometry, which are: (i) an intermittent flow that passes from quiescent states to flaring activity, (ii) no quasi-steady-state jet, (iii) no possibility of a magnetically arrested configuration. Moreover a further distinctive feature of this geometry is the intense magnetic reconnection events, occurring as layers of opposite magnetic polarity are accreted, in the vicinity of the black hole. Finally, we argue that the absence of a jet structure in such case will be a smoking gun in 43 \& 86 GHz observations.
