Test of the Einstein Equivalence Principle near the Galactic Center Supermassive Black Hole

Publication

Test of the Einstein Equivalence Principle near the Galactic Center Supermassive Black Hole

Journal Paper/Review - Mar 15, 2019

GRAVITY Collaboration, Rousset G, Rodríguez-Coira G, Rabien S, Pfuhl O, Perrin G, Perraut K, Paumard T, Ott T, Léna P, Le Bouquin J-B, Lapeyrère V, Scheithauer S, Sternberg A, Yazici S, Wiezorrek E, Wieprecht E, Widmann F, Waisberg I, von Fellenberg S, Vincent F, Tacconi L J, Sturm E, Straubmeier C, Straub O, Lacour S, Kervella P, Jocou L, Eisenhauer F, Eckart A, Ebert M, Duvert G, Dexter J, de Zeeuw P T, Coudé du Foresto V, Clénet Y, Brandner W, Berger J P, Bauböck M, Förster Schreiber N M, Garcia P, Jiménez Rosales A, Hubert Z, Horrobin M, Hippler S, Henning Th, Haubois X, Habibi M, Gillessen Sommer Silke, Genzel R, Gendron E, Gao F, Amorim A

Citation

GRAVITY Collaboration, Rousset G, Rodríguez-Coira G, Rabien S, Pfuhl O, Perrin G, Perraut K, Paumard T, Ott T, Léna P, Le Bouquin J, Lapeyrère V, Scheithauer S, Sternberg A, Yazici S, Wiezorrek E, Wieprecht E, Widmann F, Waisberg I, von Fellenberg S, Vincent F, Tacconi L, Sturm E, Straubmeier C, Straub O, Lacour S, Kervella P, Jocou L, Eisenhauer F, Eckart A, Ebert M, Duvert G, Dexter J, de Zeeuw P, Coudé du Foresto V, Clénet Y, Brandner W, Berger J, Bauböck M, Förster Schreiber N, Garcia P, Jiménez Rosales A, Hubert Z, Horrobin M, Hippler S, Henning T, Haubois X, Habibi M, Gillessen Sommer S, Genzel R, Gendron E, Gao F, Amorim A. Test of the Einstein Equivalence Principle near the Galactic Center Supermassive Black Hole. Phys Rev Lett 2019; 122:101102.

Type

Journal Paper/Review (English)

Journal

Phys Rev Lett 2019; 122

Publication Date

Mar 15, 2019

Issn Electronic

1079-7114

Pages

101102

Brief description/objective

During its orbit around the four million solar mass black hole Sagittarius A* the star S2 experiences significant changes in gravitational potential. We use this change of potential to test one part of the Einstein equivalence principle: the local position invariance (LPI). We study the dependency of different atomic transitions on the gravitational potential to give an upper limit on violations of the LPI. This is done by separately measuring the redshift from hydrogen and helium absorption lines in the stellar spectrum during its closest approach to the black hole. For this measurement we use radial velocity data from 2015 to 2018 and combine it with the gravitational potential at the position of S2, which is calculated from the precisely known orbit of S2 around the black hole. This results in a limit on a violation of the LPI of |β_{He}-β_{H}|=(2.4±5.1)×10^{-2}. The variation in potential that we probe with this measurement is six magnitudes larger than possible for measurements on Earth, and a factor of 10 larger than in experiments using white dwarfs. We are therefore testing the LPI in a regime where it has not been tested before.