Relativistic redshift of the star S0-2 orbiting the Galactic center supermassive black hole

Do, Tuan; Hees, Aurelien; Ghez, Andrea; Martinez, Gregory D.; Chu, Devin S.; Jia, Siyao; Sakai, Shoko; Lu, Jessica R.; Gautam, Abhimat K.; Kosmo O'Neil, Kelly; Becklin, Eric E.; Morris, Mark R.; Matthews, Keith; Nishiyama, Shogo; Campbell, Randy; Chappell, Samantha; Chen, Zhuo; Ciurlo, Anna; Dehghanfar, Arezu; Gallego-Cano, Eulalia Kerzendorf, Wolfgang E.; Lyke, James E.; Naoz, Smadar; Saida, Hiromi; Schödel, Rainer; Takahashi, Masaaki; Takamori, Yohsuke; Witzel, Gunther; Wizinowich, Peter
eprint arXiv:1907.10731


General Relativity predicts that a star passing close to a supermassive black hole should exhibit a relativistic redshift. We test this using observations of the Galactic center star S0-2. We combine existing spectroscopic and astrometric measurements from 1995-2017, which cover S0-2's 16-year orbit, with measurements in 2018 March to September which cover three events during its closest approach to the black hole. We detect the combination of special relativistic- and gravitational-redshift, quantified using a redshift parameter, . Our result, , is consistent with General Relativity () and excludes a Newtonian model ( ) with a statistical significance of 5 .