Nature2014-06-17 2:11 PM

强磁场驱动活动星系核的喷射流 Dynamically important magnetic fields near accreting supermassive black holes

论文摘要 

一个具有重要动力学意义的磁场最近在位于银河系中心的“人马座A*”黑洞附近被发现。这样一个磁场会影响吸积盘物理性质和向外流动的喷射流,但最新黑洞吸积盘模型却假设只存在弱磁场。Mohammad Zamaninasab等人在本文中报告说,对于所取样研究的一组76个强射电活动星系来说,磁场强度和吸积盘亮度在7个数量级上是紧密关联的。这一发现意味着,这些星系发出喷射流的区域和盘的性质受到磁场的显著影响。

Abstract 

Accreting supermassive black holes at the centres of active galaxies often produce ‘jets’—collimated bipolar outflows of relativistic particles. Magnetic fields probably play a critical role in jet formation and in accretion disk physics. A dynamically important magnetic field was recently found near the Galactic Centre black hole. If this is common and if the field continues to near the black hole event horizon, disk structures will be affected, invalidating assumptions made in standard models. Here we report that jet magnetic field and accretion disk luminosity are tightly correlated over seven orders of magnitude for a sample of 76 radio-loud active galaxies. We conclude that the jet-launching regions of these radio-loud galaxies are threaded by dynamically important fields, which will affect the disk properties. These fields obstruct gas infall, compress the accretion disk vertically, slow down the disk rotation by carrying away its angular momentum in an outflow3 and determine the directionality of jets.

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