Orbital precession of the S2 star in Scalar–Tensor–Vector Gravity

• Published in: Monthly notices of the Royal Astronomical Society Vol. 510; no. 4; pp. 4757 - 4766
• Main Authors: Della Monica, Riccardo, de Martino, Ivan, de Laurentis, Mariafelicia
• Format: Journal Article
• Language: English
• Published: London Oxford University Press 01-03-2022
• Subjects: Algorithms; Confidence intervals; Gravitation theory; Markov chains; Milky Way; Parameter modification; Precession; Relativity; Supermassive black holes; Tensors; stars: kinematics and dynamics; gravitation; Galaxy: centre; dark matter
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stab3727

ABSTRACT
We have obtained the first constraint of the parameter space of Scalar–Tensor–Vector Gravity using the motion of the S2-star around the supermassive black hole at the centre of the Milky Way, and we did not find any serious tension with General Relativity. We used the Schwarzschild-like metric of Scalar–Tensor–Vector Gravity to predict the orbital motion of S2-star, and to compare it with the publicly available astrometric data, which include 145 measurements of the positions, 44 measurements of the radial velocities of S2-star along its orbit, and only the inferred rate of precession, as the latest GRAVITY data are not yet public. We employed a Markov chain Monte Carlo algorithm to explore the parameter space, and constrained the only one additional parameter of Scalar–Tensor–Vector Gravity to α ≲ 0.662 at 99.7 ${{\ \rm per\ cent}}$ confidence level, where α = 0 reduces this modified theory of gravity to General Relativity.