Hunting for extra dimensions in black hole shadows

Abstract: Observational data of the Sagittarius A* (Sgr A*) shadow released by the Event Horizon Telescope (EHT) are used to investigate eventual deviations in the black hole shadow radius, aiming to seek physics beyond the Standard Model (SM) coming from extra-dimensional theory. We consider the brane-world scenario described by the Randall-Sundrum model and determine the black hole shadow radius correction owing to the higher dimension. From data of the shadow radius in units of BH mass determined by KECK- and VLTI-based estimates, we imposed restrictions on the deviation obtained, and one sets an upper limit to the curvature radius of Anti-de Sitter ($\mathrm{AdS_{5}}$) spacetime $\ell\lesssim4.3\times10^{-2}\,\mathrm{AU}$ (at $95\%$ confidence level).