Constraints on model parameters obtained by comparing the results of simulations to the observed spectra and image sizes of Sgr A*, as described in the text and shown in Figures 9. Each column above corresponds to a different GRMHD simulation, while the top and bottom panels correspond to the two different descriptions of the plasma thermodynamics in the funnel. The solid curves in the middle row depict the electron density normalization for which the predicted X-ray fluxes agree with 10% of the observed quiescent flux. The colored contour plots show values of χ² (see the color bar) obtained from fitting the simulated spectra to the radio/sub-millimeter data. The forward slanted lines “///” show the regions in the parameter space that are excluded because the predicted infrared flux lies outside of the observed limits. Finally, the backward slanted lines “\\\” show the constraints on the image size at 1.3 mm. The best-fit set of parameters for each simulation is obtained and is shown as a white circle or a white cross. The white circles are for fits with χ² < 1.5, which we consider to be good fits; the white crosses are for χ² > 1.5. Note that for the a0SANE models and the constant temperature a0MAD model, no set of parameters satisfies all of the observed constraints.