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arXiv 0905.2965astro-ph.GAastro-ph.CO
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活动星系核中的大尺度外流:质量供给率和吸积光度耦合的结果

On the large-scale outflows in active galactic nuclei: consequences of coupling the mass-supply rate and accretion luminosity

Ryuichi Kurosawa, Daniel Proga

摘要:

本文对在超大质量黑洞引力作用下,受到薄的紫外吸积盘和球形X射线日冕照射的缓慢旋转气体进行了二维流体动力学模拟。在半径约为10^-2 pc的条件下,我们假设吸积率等于质量供给率,并根据吸积率计算了系统的吸积光度。对于大半径(~10 pc)和高光度的高温气体模型,我们发现质量流出率(Mdot_out)和光度(L)之间有很强的相关性。描述Mdot_out-L关系的幂律指数(q)为q=2.0(+/-0.1),这与辐射驱动的恒星风和盘风模型非常相似。更令人惊讶的是,在大半径的高密度,我们发现稳态的吸积光度超过爱丁顿极限的解决方案。超爱丁顿吸积在赤道区域进行,并且是可能的,因为来自盘的辐射通量在赤道方向上由于几何缩短效应而显著减少。在所有模型中,流出是从亚开普勒旋转的流入驱动的。对于大半径的高温,流入发生在很宽的极角范围内,流出发生在相对较窄的极锥内。然而,对于超爱丁顿的情况下,在大半径的低温,流入持续只有非常接近赤道面,类似于一个薄吸积盘,而流出出现在一个广泛的半径和极角。这种极端流入流出解的几何形状非常类似于发光开普勒吸积盘的辐射驱动风。

英文摘要:

(Abridged) We present two-dimensional hydrodynamical simulations of slowly rotating gas that is under the influence of the gravity of a super massive black hole and is irradiated by a thin UV accretion disc and a spherical X-ray corona. We calculate the accretion luminosity of a system based on the accretion-rate which is assumed to be equal to the mass-supply rate at the radius of ~10^-2 pc. For the models with high temperature gas at large radii (~10 pc) and high luminosities, we find a strong correlation between the mass-outflow rate (Mdot_out) and the luminosity (L). The power law index (q) describing the Mdot_out-L relation is q=2.0(+/-0.1), which is very similar to that for radiation-driven stellar and disc wind models. More surprisingly, for high density at large radii, we find steady state solutions with the accretion luminosity exceeding the Eddington limit. The super-Eddington accretion proceeds in the equatorial region and is possible because the radiation flux from the disc is significantly reduced in the equatorial direction due to the geometrical foreshortening effect. In all models, an outflow is driven from an inflow with sub-Keplerian rotation. For high temperature at large radii, the inflow occurs over a wide range of the polar angles, and the outflow occurs in a relatively narrow polar cone. However, for the super-Eddington cases with low temperature at large radii, the inflow persists only very close to the equatorial plane, resembling a thin accretion disc, while the outflow arises in a wide range of radii and polar angles. The geometry of this extreme inflow-outflow solution is very similar to a radiation-driven wind from a luminous Keplerian accretion disc.

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