X-ray fluorescence from super-Eddington accreting black holes
  X-ray reverberation has proven to be a powerful tool capable of probing the
innermost region of accretion disks around compact objects. Current theoretical
effort generally assumes that the disk is geometrically thin, optically thick
and orbiting with Keplerian speed. Thus, these models cannot be applied to
systems where super-Eddington accretion happens because the thin disk
approximation fails in this accretion regime. Furthermore, state-of-the-art
numerical simulations show that optically thick winds are launched from the
super-Eddington accretion disks, and thereby changing the reflection geometry
significantly from the thin disk picture. We carry out theoretical
investigations on this topic by focusing on the Fe K$\alpha$ fluorescent lines
produced from super-Eddington disks, and show that their line profiles are
shaped by the funnel geometry and wind acceleration. We also systematically
compare the Fe line profiles from super-Eddington thick disks to those from
thin disks, and find that the former are substantially more blueshifted and
symmetric in shape. These results are consistent with the observed Fe K$\alpha$
line from the jetted tidal disruption event, Swift J1644, in which a transient
super-Eddington accretion disk was formed out of stellar debris. Therefore,
careful analysis of the Fe K$\alpha$ line profile can be used to identify
systems undergoing super-Eddington accretion.
