# Testing General Relativity with stellar orbits around the supermassive black hole in our Galactic center

## TL;DR

This study uses 19 years of stellar orbit data around the Galactic Center's black hole to test General Relativity and constrain potential deviations like a fifth force, finding no deviations within current measurement limits.

## Contribution

It provides the first self-consistent test of gravity in a strong regime using stellar orbital dynamics around a supermassive black hole.

## Key findings

- No deviation from General Relativity detected.
- Fifth force strength constrained to |α| < 0.016 at 150 AU.
- Upper limit on periastron drift rate of S0-2 star.

## Abstract

In this Letter, we demonstrate that short-period stars orbiting around the supermassive black hole in our Galactic Center can successfully be used to probe the gravitational theory in a strong regime. We use 19 years of observations of the two best measured short-period stars orbiting our Galactic Center to constrain a hypothetical fifth force that arises in various scenarios motivated by the development of a unification theory or in some models of dark matter and dark energy. No deviation from General Relativity is reported and the fifth force strength is restricted to an upper 95% confidence limit of $\left|\alpha\right| < 0.016$ at a length scale of $\lambda=$ 150 astronomical units. We also derive a 95% confidence upper limit on a linear drift of the argument of periastron of the short-period star S0-2 of $\left|\dot \omega_\textrm{S0-2} \right|< 1.6 \times 10^{-3}$ rad/yr, which can be used to constrain various gravitational and astrophysical theories. This analysis provides the first fully self-consistent test of the gravitational theory using orbital dynamic in a strong gravitational regime, that of a supermassive black hole. A sensitivity analysis for future measurements is also presented.