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We present 3D general relativistic magnetohydrodynamic (GRMHD) simulations ofthe accretion flow surrounding Sagittarius A* that are initialized usinglarger-scale MHD simulations of the $\sim$ 30 Wolf--Rayet (WR) stellar winds inthe Galactic center. The properties of the resulting accretion flow on horizonscales are set not by ad hoc initial conditions but by the observationallyconstrained properties of the WR winds with limited free parameters. For thisinitial study we assume a non-spinning black hole. Our simulations naturallyproduce a $\sim 10^{-8} M_\odot$ yr$^{-1}$ accretion rate, consistent withprevious phenomenological estimates. We find that a magnetically arrested flowis formed by the continuous accretion of coherent magnetic field being fed fromlarge radii. Near the event horizon, the magnetic field is so strong that ittilts the gas with respect to the initial angular momentum and concentrates theoriginally quasi-spherical flow to a narrow disk-like structure. We alsopresent 230 GHz images calculated from our simulations where the inclinationangle and physical accretion rate are not free parameters but are determined bythe properties of the WR stellar winds. The image morphology is highly timevariable. Linear polarization on horizon scales is coherent with weak internalFaraday rotation.

Ab Initio Horizon-Scale Simulations of Magnetically Arrested Accretion in Sagittarius A* Fed by Stellar Winds