GPU-Enabled General Relativistic Simulations of Misaligned Black Hole Accretion Systems

黑洞吸积盘是由围绕黑洞（BH）轨道运动的扩散物质形成的结构。 根据观测，在某些系统中，黑洞周围存在倾斜的吸积盘。 然而，人们对吸积盘的物理学知之甚少。 该项目将在Blue沃茨超级计算机上运行非常大规模的模拟，以提高我们对BH吸积盘的基本理解。 拟议的模拟结果将解决长期存在的问题，即超大质量黑洞消耗和排出气体的方式，从而对其环境产生反馈。 这些结果将使物理学界获得第一原理的理解盘物理在典型的倾斜BH吸积systems.Gas落入BH从大的距离是不知道BH自旋方向，吸积盘和BH自旋之间的错位预计是常见的。然而，人们对倾斜盘的物理学知之甚少，即使是对“标准”的、几何上薄的、辐射效率高的吸积盘也是如此，这种吸积盘为被称为类星体的活动星系核提供动力，并被认为是广义相对论和盘物理学的最佳观测测试。特别是，人们仍然不明白旋转黑洞的弯曲时空是如何在倾斜盘的结构上留下自己的印记的。该项目将利用这样一个事实，即在其核心，BH吸积盘是由广义相对论磁流体动力学运动方程很好地描述的。通过对倾斜的薄盘和厚盘进行直接GRMHD模拟，该项目将获得对典型倾斜BH吸积系统中盘物理的第一原理理解。为了克服这些模拟的昂贵性，该项目构建了第一个GPU加速的GRMHD代码H-AMR，它能够自适应网格细化，非常适合Blue沃茨超级计算机。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

A black hole accretion disk is a structure formed by diffused materials in orbital motion around a black hole (BH). From observations, the presence of tilted accretion disks around a BH is detected in some systems. However, the physics of accretion disks is poorly understood. This project will run very large scale simulations on the Blue Waters supercomputer to improve our fundamental understanding of BH accretion disks. Results of the proposed simulations will address long-standing questions in the way supermassive black holes consume and expel gas, and thereby exert feedback on their environment. These results will allow the physics community to gain first-principles understanding of disk physics in typical tilted BH accretion systems.Gas falling into a BH from large distances is unaware of BH spin direction, and misalignment between the accretion disk and BH spin is expected to be common. However, the physics of tilted disks is poorly understood, even for the "standard", geometrically thin, radiatively efficient accretion disks that power active galactic nuclei known as quasars and thought to provide the best observational tests of general relativity and disk physics. In particular, it is still not understood how the curved space-time of a spinning black hole imprints itself on the structure of the tilted disks. This project will make use of the fact that, at their core, BH accretion disks are well-described by the general relativistic magnetohydrodynamics (GRMHD) equations of motion. By carrying out direct GRMHD simulations of tilted thin and thick disks, the project will obtain the first-principles understanding of disk physics in typical, tilted BH accretion systems. To surmount the prohibitively expensive nature of these simulations, the project has constructed the first GPU-accelerated GRMHD code, H-AMR, which is capable of adaptive mesh refinement and is ideally suited for the Blue Waters supercomputer.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.