  About a hundred tidal disruption events (TDEs) have been observed and they
exhibit a wide range of emission properties both at peak and over their
lifetimes. Some TDEs peak predominantly at X-ray energies while others radiate
chiefly at UV and optical wavelengths. While the peak luminosities across TDEs
show distinct properties, the evolutionary behavior can also vary between TDEs
with similar peak emission properties. At late time, some optical TDEs
rebrighten in X-rays, while others maintain strong UV/optical emission
components. In this Letter, we conduct three-dimensional general relativistic
radiation magnetohydrodynamics simulations of TDE accretion disks at varying
accretion rates ranging from a few to a few tens of the Eddington accretion
rate. We make use of Monte Carlo radiative transfer simulations to calculate
the reprocessed spectra at various inclinations and at different evolutionary
stages. We confirm the unified model proposed by Dai et al. (2018), which
predicts that the observed emission largely depends on the viewing angle of the
observer with respect to the disk orientation (X-ray strong when viewed face-on
and UV/optically strong when viewed disk-on). What is more, we find that disks
with higher accretion rates have elevated wind and disk densities, which
increases the reprocessing of the high-energy radiation and thus generally
augments the optical-to-X-ray flux ratio along a particular viewing angle. This
implies that at later times, as the accretion level declines, we expect the
funnel to effectively open up and allow more X-rays to leak out along
intermediate viewing angles. Such dynamical model for TDEs can provide a
natural explanation for the diversity in the emission properties observed in
TDEs at peak and along their temporal evolution.

High Energy Astrophysical Phenomena