Young S, Axon D J, Robinson A, Hough J H, Smith J E
Department of Physics, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, New York 14623, USA.
Nature. 2007 Nov 1;450(7166):74-6. doi: 10.1038/nature06319.
It is now widely accepted that most galaxies undergo an active phase, during which a central super-massive black hole generates vast radiant luminosities through the gravitational accretion of gas. Winds launched from a rotating accretion disk surrounding the black hole are thought to play a critical role, allowing the disk to shed angular momentum that would otherwise inhibit accretion. Such winds are capable of depositing large amounts of mechanical energy in the host galaxy and its environs, profoundly affecting its formation and evolution, and perhaps regulating the formation of large-scale cosmological structures in the early Universe. Although there are good theoretical grounds for believing that outflows from active galactic nuclei originate as disk winds, observational verification has proven elusive. Here we show that structures observed in polarized light across the broad Halpha emission line in the quasar PG 1700+518 originate close to the accretion disk in an electron scattering wind. The wind has large rotational motions (approximately 4,000 km s(-1)), providing direct observational evidence that outflows from active galactic nuclei are launched from the disks. Moreover, the wind rises nearly vertically from the disk, favouring launch mechanisms that impart an initial acceleration perpendicular to the disk plane.
现在人们普遍认为，大多数星系都会经历一个活跃阶段，在此期间，一个中心超大质量黑洞通过气体的引力吸积产生巨大的辐射光度。从围绕黑洞的旋转吸积盘发射出的风被认为起着关键作用，使吸积盘能够摆脱否则会抑制吸积的角动量。这种风能够在宿主星系及其周围环境中沉积大量机械能，深刻影响其形成和演化，甚至可能调节早期宇宙中大规模宇宙结构的形成。尽管有充分的理论依据相信活动星系核的外流起源于盘风，但观测验证却难以实现。在这里，我们表明，在类星体PG 1700+518的宽Hα发射线中观测到的偏振光结构起源于电子散射风中靠近吸积盘的区域。这种风具有较大的旋转运动（约4000千米每秒），提供了活动星系核的外流从盘发射的直接观测证据。此外，风几乎垂直于盘上升，这有利于那些能赋予垂直于盘平面的初始加速度的发射机制。
