Dynamics of Line-driven Disk Winds in Active Galactic Nuclei
Dynamics of Line-driven Disk Winds in Active Galactic Nuclei
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DOI：
10.1086/317154
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发表时间：
2000
期刊：
影响因子：
--
通讯作者：
D. Proga;J. Stone;T. Kallman
中科院分区：
文献类型：
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作者：
D. Proga;J. Stone;T. Kallman
本文给出了活动星系核吸积盘线驱动风的轴对称含时流体动力学计算结果。我们假设圆盘是平的，开普勒，几何上薄，光学上厚，根据α圆盘的规定辐射。活动星系核的中心引擎是电离X射线和风驱动紫外光子的来源。为了计算辐射力，我们考虑了来自圆盘和中央引擎的辐射。由中心机的光电离和加热率自洽地计算了风中气体的温度和电离状态。我们发现，一个磁盘吸积到一个108米的黑洞在1.8米的速度，可以发射风在~1016厘米的中央引擎。来自中心物体的X射线被盘的大气显著衰减，因此它们不能阻止局部盘辐射将物质推离盘。然而，在圆盘上方气流的超音速部分，X射线可以覆盖气体并降低风的终端速度。对于合理的X射线不透明度，例如，当κX = 40 g-1 cm 2时，盘风可以被中心紫外线辐射加速到15，000 km s-1，距离中心发动机约1017 cm。盘风的覆盖系数约为0.2。风是不稳定的，由一个不透明的，缓慢的垂直流动的磁盘附近，是由一个高速流的极地一侧的边界。通过快速流的典型柱密度是1023 cm-2的几倍，因此流对于UV辐射是光学薄的。这种低的柱密度正是气体可以被加速到高速度的原因。快速流贡献了近100%的总风质量损失率为0.5百万年-1。
We present the results of axisymmetric time-dependent hydrodynamic calculations of line-driven winds from accretion disks in active galactic nuclei (AGNs). We assume the disk is flat, Keplerian, geometrically thin, and optically thick, radiating according to the α-disk prescription. The central engine of the AGN is a source of both ionizing X-rays and wind-driving UV photons. To calculate the radiation force, we take into account radiation from the disk and the central engine. The gas temperature and ionization state in the wind are calculated self-consistently from the photoionization and heating rate of the central engine. We find that a disk accreting onto a 108 M☉ black hole at the rate of 1.8 M☉ yr-1 can launch a wind at ~1016 cm from the central engine. The X-rays from the central object are significantly attenuated by the disk atmosphere so they cannot prevent the local disk radiation from pushing matter away from the disk. However, in the supersonic portion of the flow high above the disk, the X-rays can overionize the gas and decrease the wind terminal velocity. For a reasonable X-ray opacity, e.g., κX = 40 g-1 cm2, the disk wind can be accelerated by the central UV radiation to velocities of up to 15,000 km s-1 at a distance of ~1017 cm from the central engine. The covering factor of the disk wind is ~0.2. The wind is unsteady and consists of an opaque, slow vertical flow near the disk that is bounded on the polar side by a high-velocity stream. A typical column density through the fast stream is a few times 1023 cm-2 so the stream is optically thin to the UV radiation. This low column density is precisely why gas can be accelerated to high velocities. The fast stream contributes nearly 100% to the total wind mass-loss rate of 0.5 M☉ yr-1.