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

Gas falling into a black hole (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, we still do not understand how the curved space-time of a spinning black hole imprints itself on the structure of the tilted disks. In this proposal we make use of the fact that, at their core, black hole accretion disks and jets are well-described by the general relativistic magnetohydrodynamics (GRMHD) equations of motion. By carrying out direct GRMHD simulations of tilted thin and thick disks, we will obtain the first-principles understanding of disk physics in typical, tilted BH accretion systems. To surmount the prohibitively expensive nature of these simulations, we have 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.