Diverse Emission Patterns from Precessing Super-Eddington Disks Formed in Tidal Disruption Events

Abstract A tidal disruption event (TDE) occurs when a star passes within the tidal radius of a supermassive black hole (SMBH). In TDEs, it is expected that the orbital angular momentum of the disrupted star is generally misaligned with the SMBH spin axis, which should result in a misaligned super-Eddington disk precessing around the SMBH spin axis due to the Lense–Thirring effect. In this paper, we investigate the distinct observational signatures produced from such TDE disks by performing radiative transfer calculations upon previous super-Eddington disk simulations. We demonstrate that the precession of the disk and wind drive time-dependent obscuration and reprocessing of X-ray radiation. Depending on the orientation of the viewing angle of the observer and the tilt angle of the disk, four main types of variability are induced. (1) Smooth TDEs: The emissions from these TDEs show no fluctuations. (2) The Dimmer: The main emission type (X-ray or optical) stays the same, with small to moderate modulations of brightness. (3) The Blinker: X-ray and optical emissions take turns to dominate in one cycle of precession, with dramatic changes in the X-ray fluxes. (4) The Siren: X-ray and optical emissions take over each other twice per cycle, possibly with two different peak X-ray fluxes within one cycle. In all three scenarios, we observe an inverse correlation between X-ray and optical emissions. Our model provides a physical framework for interpreting TDE multiwavelength variability through disk precession dynamics and gives an alternative interpretation to the interesting case of J045650.3-203750, which was suggested to be a repeated partial TDE previously.