标题： 关于黑洞周围厚吸积盘的稳定性 显示英文标题

标题： On the stability of thick accretion disks around black holes

摘要： 分辨所谓黑洞周围厚吸积盘的逃逸不稳定性出现的可能性，是大多数宇宙伽马射线暴模型中的一个重要问题。 为此，我们通过广义相对论中黑洞与环状结构系统的非稳态流体力学模拟来研究这一现象。 中央黑洞的演化被假设为一系列质量与自旋不断增加的克尔黑洞序列，其增长速度由盘中物质通过黑洞事件视界螺旋进入时的质量和角动量转移所控制。 盘的自引力被忽略。 我们发现，当允许黑洞质量和自旋增加时，常角动量盘会在动力学时间尺度上（几个轨道周期）经历逃逸不稳定性。 然而，我们的模拟表明，盘向外的比角动量轻微增加具有显著的稳定效应。 我们在广义相对论框架下得到的结果，与基于静态模型以及牛顿和伪牛顿引力势的时间依赖模拟的早期研究结果大致一致。 显示英文摘要

摘要： Discerning the likelihood of the so-called runaway instability of thick accretion disks orbiting black holes is an important issue for most models of cosmic gamma-ray bursts. To this aim we investigate this phenomenon by means of time-dependent, hydrodynamical simulations of black hole plus torus systems in general relativity. The evolution of the central black hole is assumed to be that of a sequence of Kerr black holes of increasing mass and spin, whose growth rate is controlled by the transfer of mass and angular momentum from the material of the disk spiralling in through the event horizon of the black hole. The self-gravity of the disk is neglected. We find that when the black hole mass and spin are allowed to increase, constant angular momentum disks undergo a runaway instability on a dynamical timescale (a few orbital periods). However, our simulations show that a slight increase of the specific angular momentum of the disk outwards has a dramatic stabilizing effect. Our results, obtained in the framework of general relativity, are in broad agreement with earlier studies based both on stationary models and on time-dependent simulations with Newtonian and pseudo-Newtonian gravitational potentials.