Active galactic nuclei: internal dynamics and formation of emission clouds
Active galactic nuclei: internal dynamics and formation of emission clouds
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DOI：
10.1086/163278
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发表时间：
1985-07
期刊：
影响因子：
--
通讯作者：
I. Shlosman;P. Vitello;G. Shaviv
中科院分区：
文献类型：
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作者：
I. Shlosman;P. Vitello;G. Shaviv
我们表明，冷紫外吸积盘，如果存在于活动星系核，可以是线驱动风的来源。亚临界盘被证明能够在连续体中产生光学薄的风，这些风被线中的辐射压力加速（即，通过在多普勒频移的光学厚UV共振线中的盘连续体光子的吸收和散射）。本文给出并讨论了超大质量黑洞盘外流的数值模拟结果。启动风的必要条件是当地辐射通量必须在既有线路的能量范围内达到峰值。因此，风的底部必须与中心区域屏蔽，中心区域被假定为发射幂律分布的辐射。磁盘大气可以提供这种屏蔽。风的特点是陡峭的速度梯度和高的渐近速度，approx.10/sup 9/ cm s/sup-1/，在广泛的发射线区域的类星体和Seyfert星系，是热不稳定的，因为它们加热。这导致了两相平衡：冷云嵌入在热的康普顿加热的背景中。热风为稠密和巨大的云提供了压力约束。云的形成和他们的未来演变的相关时间尺度进行了估计，并讨论了广泛的发射线区域的动力学的影响。«少
We show that cool UV accretion disks, if present in active galactic nuclei,can be sources of line-driven winds. Subcritical disks are shown to be capable of producing winds optically thin in the continuum, which are accelerated by radiation pressure in lines (i.e., by absorption and scattering of disk-continuum photons in the Doppler-shifted optically thick UV resonance lines). Results of a numerical simulation to the outflow from a disk around a supermassive black hole are presented and discussed. The necessary condition for initiating the wind is that the local radiative flux must be peaked in the energy range of existing lines. The base of the wind must therefore be shielded from the central region, which is assumed to emit power-law-distributed radiation. The disk atmosphere can provide such shielding. The winds are characterized by steep velocity gradients and high asymptotic velocities, approx.10/sup 9/ cm s/sup -1/, as observed in broad emission-line regions of QSOs and Seyfert galaxies, and are thermally unstable, as they heat up. This results in a two-phase equilibrium: cold clouds embedded in a hot, Compton-heated background. The hot wind provides the pressure confinement for the dense and massive clouds. The relevant time scales for the cloud formation and theirmore » future evolution are estimated, and the implications for the dynamics of the broad emission-line regions are discussed.« less