Constraints on metric-affine gravity black holes from the stellar motion at the Galactic Center
Abstract
We consider a static, spherically symmetric space-time with an electric field arising from a quadratic metric-affine extension of General Relativity. Such a space-time is free of singularities in the centre of the black holes, while at large distances it quickly boils down to the usual Reissner-Nordstr\"om solution. We probe this space-time metric, which is uniquely characterized by two length scales, rq and , using the astrometric and spectroscopic measurements of the orbital motion of the S2 star around the Galactic Center. Our analysis constrains rq to be below 2.7M for values <120 AU, strongly favouring a central object that resembles a Schwarzschild black hole.
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