Beyond Shakura-Sunyaev: First-Principles Physics of Accretion Disks in Active Galactic Nuclei

AST-0307657 Blaes类星体和活动星系核的巨大能量输出的机制几乎可以肯定是等离子体吸积到超大质量黑洞上，可能是以旋转支撑的吸积盘的形式。 吸积盘的标准模型一直基于一个特设的湍流角动量输运和能量耗散的唯象处方，由Shakura Sunyaev在大约30年前提出。目前的研究将创建本地，辐射磁流体动力学模拟这种吸积流，第一次没有特设的假设，这最终应该解除标准模型中长期存在的不确定性。 现代数值技术的力量和复杂性将被用来确定是否有一个可实现的热稳定的平衡状态，有多少湍流应力是目前在辐射压力为主的流动，在流动中的平均垂直分布，以及热量和能量的传输率。 这项工作还将考虑可压缩性，密度不均匀性，以及光子气泡和磁声波不稳定性的非线性发展。在流中不同位置的湍流状态的快照将提供给世界各地的科学家，以添加其他物理或考虑其他影响。 一些测试将是第一次可能的，因为模型将基于物理学而不是现象学的处方。 研究生和本科生将参与这项研究。 模拟结果的动画将有效地作为研究人员关于黑洞天体物理学有趣复杂性的公开演讲的一部分，这仍然令人着迷。

AST-0307657BlaesThe mechanism responsible for the prodigious power output of quasars and active galactic nuclei is almost certainly the accretion of plasma onto super-massive black holes, probably in the form of a rotationally supported accretion disk. The standard model of accretion disks has been based on an ad hoc phenomenological prescription for turbulent angular momentum transport and energy dissipation, introduced by Shakura & Sunyaev some thirty years ago.The current research will create local, radiation-magnetohydrodynamical simulations of this accretion flow, for the first time with no ad-hoc assumptions, which should finally lift the long-standing uncertainties in the standard model. The power and sophistication of modern numerical techniques will be used to determine whether there is an achievable thermally stable equilibrium state, how much turbulent stress is present in radiation-pressure-dominated flows, the average vertical distribution in the flow, and the rates of heat and energy transport. The work will also consider compressibility, density inhomogeneities, and the nonlinear development of photon-bubble and magnetoacoustic-wave instabilities.Snapshots of the turbulent state at different locations in the flow will be made available for scientists everywhere, to add other physics or consider additional effects. Some tests will be possible for the first time because the models will be based on physics and not phenomenological prescriptions. Graduate and undergraduate students will be involved in the research. Animations of the simulation results will be effective as part of the investigators' public talks about the interesting complexity of black hole astrophysics, which continues to fascinate.