Testing the gravitational theory with short-period stars around our Galactic Center

TL;DR

This paper reviews over 20 years of observations of short-period stars near the Galactic Center to test gravitational theories in strong fields, providing constraints on new physics and predictions for relativistic effects.

Contribution

It presents new constraints on a hypothetical fifth force and limits on relativistic precession using long-term stellar orbit data around the black hole.

Findings

Constraint on a fifth force from 19 years of data

Upper limit on periastron advance of S0-2

Predicted measurement of relativistic redshift in 2018

Abstract

Motion of short-period stars orbiting the supermassive black hole in our Galactic Center has been monitored for more than 20 years. These observations are currently offering a new way to test the gravitational theory in an unexplored regime: in a strong gravitational field, around a supermassive black hole. In this proceeding, we present three results: (i) a constraint on a hypothetical fifth force obtained by using 19 years of observations of the two best measured short-period stars S0-2 and S0-38 ; (ii) an upper limit on the secular advance of the argument of the periastron for the star S0-2 ; (iii) a sensitivity analysis showing that the relativistic redshift of S0-2 will be measured after its closest approach to the black hole in 2018.