We obtain estimates of Sgr A* accretion flow and black hole parameters by fitting polarized sub-mm observations with spectra computed using three-dimensional ( 3D ) general relativistic ( GR ) magnetohydrodynamical ( MHD ) ( GRMHD ) simulations .
Observations are compiled from averages over many epochs from reports in 29 papers for estimating the mean fluxes F _ { \nu } , linear polarization ( LP ) fractions , circular polarization ( CP ) fractions , and electric vector position angles ( EVPAs ) .
GRMHD simulations are computed with dimensionless spins a _ { * } = 0 , 0.5 , 0.7 , 0.9 , 0.98 over a 20 , 000 M time interval .
We perform fully self-consistent GR polarized radiative transfer using our new code to explore the effects of spin a _ { * } , inclination angle \theta , position angle ( PA ) , accretion rate \dot { M } , and electron temperature T _ { e } ( T _ { e } is reported for radius 6 M ) .
By fitting the mean sub-mm fluxes and LP/CP fractions , we obtain estimates for these model parameters and determine the physical effects that could produce polarization signatures .
Our best bet model has a _ { * } = 0.5 , \theta = 75 ^ { \circ } , { PA } = 115 ^ { \circ } , \dot { M } = 4.6 \times 10 ^ { -8 } M _ { \odot } { year } ^ { -1 } , and T _ { e } = 3.1 \times 10 ^ { 10 } K at 6 M .
The sub-mm CP is mainly produced by Faraday conversion as modified by Faraday rotation , and the emission region size at 230 GHz is consistent with the VLBI size of 37 \mu as .
Across all spins , model parameters are in the ranges \theta = 42 ^ { \circ } -75 ^ { \circ } , \dot { M } = ( 1.4 - 7.0 ) \times 10 ^ { -8 } M _ { \odot } { year } ^ { -1 } , and T _ { e } = ( 3 - 4 ) \times 10 ^ { 10 } K. Polarization is found both to help differentiate models and to introduce new observational constraints on the effects of the magnetic field that might not be fit by accretion models so-far considered .