SIMBAD references

We study model images and polarization maps of Sagittarius A* at 230 GHz. We post-process general relativistic magnetohydrodynamic simulations and perform a fully relativistic radiative transfer calculation of the emitted synchrotron radiation to obtain polarized images for a range of mass accretion rates and electron temperatures. At low-accretion rates, the polarization map traces the underlying toroidal magnetic field geometry. At high-accretion rates, we find that Faraday rotation internal to the emission region can depolarize and scramble the map. We measure the net linear polarization fraction and find that high-accretion rate 'jet-disc' models are heavily depolarized and are therefore disfavoured. We show how Event Horizon Telescope measurements of the polarized 'correlation length' over the image provide a model independent upper limit on the strength of these Faraday effects, and constrain plasma properties like the electron temperature and magnetic field strength.