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arXiv 0705.0791astro-ph
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一个新的黑洞吸积标准模型

Towards a New Standard Model for Black Hole Accretion

Zdenka Kuncic, Geoffrey V. Bicknell

摘要:

简要回顾了黑洞吸积盘理论的最新进展,强调了磁流体动力学(MHD)应力在角动量输运中的重要作用。与吸积有关的外流现象的明显普遍性是一个强有力的指标,表明大尺度MHD扭矩有利于角动量的垂直传输。这导致角动量传输的整体速率增强,并允许物质以有趣的速率进行吸积。此外,我们认为,当垂直运输是重要的,径向结构的吸积盘修改在小半径,这会影响磁盘发射光谱。我们提出了一个简单的模型,展示了如何充满活力,磁驱动的外流修改相对于标准的吸积盘理论预测的紧急磁盘发射光谱。预测的光谱与观测的类星体光谱能量分布的比较表明,使用标准盘模型推断的质量吸积率可能会严重低估其真实值。

英文摘要:

We briefly review recent developments in black hole accretion disk theory, emphasizing the vital role played by magnetohydrodynamic (MHD) stresses in transporting angular momentum. The apparent universality of accretion-related outflow phenomena is a strong indicator that large-scale MHD torques facilitate vertical transport of angular momentum. This leads to an enhanced overall rate of angular momentum transport and allows accretion of matter to proceed at an interesting rate. Furthermore, we argue that when vertical transport is important, the radial structure of the accretion disk is modified at small radii and this affects the disk emission spectrum. We present a simple model demonstrating how energetic, magnetically-driven outflows modify the emergent disk emission spectrum with respect to that predicted by standard accretion disk theory. A comparison of the predicted spectra against observations of quasar spectral energy distributions suggests that mass accretion rates inferred using the standard disk model may severely underestimate their true values.

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