Hunting for extra dimensions in black hole shadows

TL;DR

This paper uses EHT observations of Sgr A* to test for extra-dimensional effects on black hole shadows, setting limits on the curvature radius of AdS5 spacetime within brane-world models.

Contribution

It provides the first observational constraints on extra-dimensional theories using black hole shadow data from the EHT.

Findings

Upper limit on AdS5 curvature radius:  extless 4.3 imes 10^{-2} AU

Constraints derived from shadow radius measurements of Sgr A*

Supports the viability of brane-world scenarios within observational bounds.

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).