Radiative Models of Sgr A* from GRMHD Simulations
  Using flow models based on axisymmetric general relativistic
magnetohydrodynamics (GRMHD) simulations, we construct radiative models for sgr
A*. Spectral energy distributions that include the effects of thermal
synchrotron emission and absorption, and Compton scattering, are calculated
using a Monte Carlo technique. Images are calculated using a ray-tracing
scheme. All models are scaled so that the 230 GHz flux density is 3.4 Jy. The
key model parameters are the dimensionless black hole spin a*, the inclination
i, and the ion-to-electron temperature ratio Ti/Te. We find that: (1) models
with Ti/Te=1 are inconsistent with the observed submillimeter spectral slope;
(2) the X-ray flux is a strongly increasing function of a*; (3) the X-ray flux
is a strongly increasing function of i; (4) 230 GHz image size is a complicated
function of i, a*, and Ti/Te, but the Ti/Te = 10 models are generally large and
at most marginally consistent with the 230 GHz VLBI data; (5) for models with
Ti/Te=10 and i=85 deg the event horizon is cloaked behind a synchrotron
photosphere at 230 GHz and will not be seen by VLBI, but these models
overproduce NIR and X-ray flux; (6) in all models whose SEDs are consistent
with observations the event horizon is uncloaked at 230 GHz; (7) the models
that are most consistent with the observations have a* \sim 0.9. We finish with
a discussion of the limitations of our model and prospects for future
improvements.
