Collaborative Research: The Physics of Accretion Disks

通过理解吸积的基本机制是由磁旋转不稳定性驱动的磁流体动力学（MHD）湍流引起的角动量输运，可以在详细水平上研究黑洞吸积的天体物理特性。在NSF之前的支持下，该团队开发了一套牛顿和广义相对论MHD数值模拟代码，适用于探索黑洞吸积流和它们有时产生的喷流的全局特性。这个由Krolik博士领导的合作项目现在将扩展先前的工作，以考虑吸积热力学和能量学，大规模磁场的影响，以及在远距离上斜向黑洞旋转轴的吸积流如何与Lense-Thirring扭矩相互作用。重点将放在创建动态模拟数据和可观察属性之间的定量联系。这项工作应该为关于有多少大尺度磁通量可以深入吸积流的争论提供真正的指导。它还应该揭示，在具有内在大尺度结构的磁场的作用下，吸积流与没有这种结构的吸积流是如何不同的。此外，计算吸积流中的MHD应力对于引力作用下磁盘弯曲程度的问题至关重要，并且应该很快就可以用足够的分辨率计算磁盘结构来解决这个问题。仿真代码和特定模型的数据都将提供给社区，加强该学科的软件基础设施。该项目将为研究生提供数值模拟技术方面的培训。基于模拟结果的成功的公众宣传工作将继续进行，包括天文馆展览和电视纪录片。

AST-0908336/0908869Krolik/HawleyArmed by an understanding that the fundamental mechanism of accretion is angular momentum transport due to magnetohydrodynamic (MHD) turbulence driven by the magneto-rotational instability, it has become possible to investigate at a detailed level the astrophysical properties of accretion onto black holes. With previous NSF support, this team has developed a suite of Newtonian and general relativistic MHD numerical simulation codes suitable for exploring the global properties of accretion flows onto black holes and the jets they sometimes generate. This collaborative project, led by Dr. Krolik, will now extend prior work to consider accretion thermodynamics and energetics, the impact of large-scale magnetic fields, and how an accretion flow oriented obliquely to the black hole rotation axis at large distances interacts with Lense-Thirring torques. Emphasis will be placed throughout on creating quantitative links between dynamical simulation data and observable properties.This work should provide genuine guidance for the controversy over how much large-scale magnetic flux may be brought deep into the accretion flow. It should also reveal how accretion flows stressed by magnetic fields with intrinsic large-scale structure may differ from those without. In addition, computing MHD stresses within the accretion flow is essential to the question of the extent of disk bending by gravitomagnetic forces, and it should soon be possible to calculate disk structure with sufficient resolution to address this issue.Both simulation codes and data from specific models will be made available to the community, strengthening the software infrastructure of the discipline. The project will provide graduate student training in numerical simulation techniques. Successful public outreach efforts based on simulation results will continue, including planetarium shows and television documentaries.