Polarized Millimeter and Submillimeter Emission from Sagittarius A* at the Galactic Center

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Abstract
The recent detection of significant linear polarization at millimeter and submillimeter wavelengths in the spectrum of Sagittarius A* (if confirmed) will be a useful probe of the conditions within several Schwarzschild radii (rS) of the event horizon at the Galactic center. Hydrodynamic simulations of gas flowing in the vicinity of this object suggest that the infalling gas circularizes when it approaches within 5-25rS of the black hole. We suggest that the submillimeter "excess" of emission seen in the spectrum of Sgr A* may be associated with radiation produced within the inner Keplerian region and that the observed polarization characteristics provide direct evidence for this phenomenon. The overall spectrum from this region, including the high-energy component due to bremsstrahlung and inverse Compton scattering processes, is at or below the recent Chandra measurement and may account for the X-ray source if it turns out to be the actual counterpart to Sgr A*.