  We use the Athena++ Monte Carlo (MC) radiation transfer module to
post-process simulation snapshots from non-relativistic Athena++ radiation
magnetohydrodynamic (RMHD) simulations. These simulations were run using a gray
(frequency integrated) approach but were also restarted and ran with a
multi-group approach that accounts for Compton scattering with a Kompaneets
operator. These simulations produced moderately super-Eddington accretion rates
onto a 6.62 $M_\odot$ black hole. Since we only achieve inflow equilibrium out
to 20-25 gravitational radii, we focus on the hard X-ray emission. We provide a
comparison between the MC and RMHD simulations showing that the treatment of
Compton scattering in the gray RMHD simulations underestimates the gas
temperature in the regions above and below the accretion disk. In contrast, the
restarted multi-group snapshots provides a treatment for the radiation field
that is more consistent with the MC calculations, and result in post-processed
spectra with harder X-ray emission compared to their gray snapshot
counterparts. We characterize these MC post-processed spectra using commonly
employed phenomenological models used for spectral fitting. We also attempt to
fit our MC spectra directly to observations of the ultraluminous X-ray source
(ULX) NGC 1313 X-1, finding best fit values that are competitive to
phenomenological model fits, indicating that first principle models of
super-Eddington accretion may adequately explain the observed hard X-ray
spectra in some ULX sources.
