General Relativistic Radiation Magnetohydrodynamics Simulations of Precessing Tilted Super-Eddington Disks

We perform a three-dimensional general relativistic radiation magnetohydrodynamics simulation of a tilted super-Eddington accretion disk around a spinning black hole (BH). The disk, which tilts and twists as it approaches the BH, precesses while maintaining its shape. The gas is mainly ejected around the rotation axis of the outer part of the disk rather than around the spin axis of the BH. The disk precession changes the ejection direction of the gas with time. The radiation energy is also released in approximately the same direction as the outflow, so the precession is expected to cause a quasiperiodic time variation of the observed luminosity. The timescale of the precession is about 10 s for a 10 M ⊙ BH and for the radial extent of a disk of several tens of gravitational radii, where M ⊙ is the solar mass. This timescale is consistent with the frequency of the low-frequency quasiperiodic oscillation (0.01–1 Hz) observed in some ultraluminous X-ray sources.