标题： 超大质量盘的物理：形成与塌缩 显示英文标题

标题： Physics of Supermassive Disks: Formation and Collapse

摘要： 超大质量盘被认为是超大质量黑洞的前身，这些黑洞被认为驱动了类星体，并存在于星系中心。 本文回顾了此类盘的形成场景，并指出与恒星动力学方案相比，气体动力学方案更为有利，尽管后者可能是黑洞增长的重要供料机制。 提出了一种新的自相似模型，用于描述由于辐射引起的应力导致的自引力盘坍缩，该模型适用于两种不同的情况：辐射粘性和康普顿拖拽。 发现仅由辐射粘性引起的坍缩时间尺度是哈勃时间的几分之一，即$\tau_\gamma \sim{\sigma_T c/ (m_p G)} ({L_{edd}/ L}) \simeq 6 \times 10^9$年，这表明坍缩可能很慢，而且在广义相对论效应占据主导之前，磁场可能发挥了重要作用。 还提出了一个自引力盘由于宇宙微波背景的康普顿拖拽而坍缩的模型，该模型在红移$1400>z\gsim 300$处被发现有效。 据提议，通过这一机制形成的较小的$\lsim 10^5 \Msun$物体可以在$z \sim 20$时通过动力学摩擦合并并聚集成高红移的类星体。 最后，作为最终坍缩前阶段的超大质量恒星（可能是超大质量盘阶段的产物）也进行了简要回顾。 显示英文摘要

摘要： Supermassive disks are thought to be precursors of supermassive black holes that are believed to power quasars and exist at centers of galaxies. Formation scenarios of such disks are reviewed and it is argued that gas dynamical schemes are favourable compared to stellar dynamical schemes which could however be important feeding mechanisms for the growth of the black hole. A new self-similar model of a collapse of a self-gravitating disk due to radiation induced stresses applicable to two different situations of radiative viscosity and Compton drag is presented. The collapse timescale purely due to radiative viscosity is found to be a fraction of Hubble time, $\tau_\gamma \sim{\sigma_T c/ (m_p G)} ({L_{edd}/ L}) \simeq 6 \times 10^9$yrs is slow and probably magnetic fields play an important role before general relativistic effects take over. A model of self-gravitating disk collapsing due to Compton drag by the Cosmic Microwave Background is also presented which is found to be effective at redshifts $1400>z\gsim 300$. It is proposed that the small $\lsim 10^5 \Msun$ objects that form by this mechanism by $z \sim 20$ can merge and coalesce by dynamical friction to form the high redshift quasars seen. Supermassive stars which are systems (and could be end products of a supermassive disk phase) en route to the final collapse are also briefly reviewed.