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

Hees, A.; Ghez, A. M.; Do, T.; Lu, J. R.; Morris, M. R.; Becklin, E. E.; Witzel, G.; Boehle, A.; Chappell, S.; Chen, Z.; Chu, D.; Ciurlo, A.; Dehghanfar, A.; Gallego-Cano, E.; Gautam, A.; Jia, S.; Kosmo, K.; Martinez, G. D.; Matthews, K.; Naoz, S.; Sakai, S.; Schödel, R.

May, 2017

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.