Selfgravity and QSO Accretion Disks

本项目的目标是建立一个动态自洽的类星体吸积模型。类星体吸积盘的外部容易发生引力不稳定，问题是要解释为什么气态盘没有完全碎裂成恒星，而是提供给类星体。部分气体可能会形成恒星或小黑洞，加热圆盘，推迟进一步的碎裂，但稳定大圆盘所需的能量可能超过了这种方式所能提供的能量。PI和学生的初步计算表明，局部加热可以保持边缘稳定，这项工作将进一步研究这种影响及其可能的来源，并探索可能产生更大引力稳定性的替代(更快)吸积模式。来自这项部分分析但主要是数值工作的预测将与观测结果进行测试，比较结果将反馈到建模过程中。可能需要能量投入和替代的快速积累相结合。该项目将培训研究生进行研究，并通过出版、会议和机构陈述来传达他们的结果。超大质量黑洞、轨道运动、吸积和其他与这项研究相关的概念的教学描述将被用来吸引小学生的兴趣。

AST-0307558GoodmanThe goal of this project is a dynamically self-consistent model for accretion in quasars. The outer parts of quasar accretion disks are prone to gravitational instability, and the problem is to explain why the gaseous disk does not fragment entirely into stars rather than feed the quasar. Some fraction of the gas may form stars or small black holes and heat the disk, postponing further fragmentation, but the energy required to stabilize large disks is probably more than can be made available this way. Preliminary calculations by the PI and students suggest that local heating can maintain marginal stability, and this work will further investigate this effect and its possible sources, as well as explore alternative (faster) accretion modes that could yield greater gravitational stability. Predictions from this partly analytical but mostly numerical work will be tested against observations, and the comparisons will feed back into the modeling. A combination of energy inputs and alternative rapid accretion may be required.The project will train graduate students in research and in the communication of their results by publication and by conference and institutional presentations. Pedagogical accounts of super-massive black holes, orbital motions, accretion, and other concepts related to this research, will be used to capture the interest of schoolchildren.