https://doi.org/10.1140/epjc/s10052-024-12477-3
Regular Article - Theoretical Physics
Relativistic orbits of S2 star in the presence of scalar field
1
International Centre for Space and Cosmology, Ahmedabad University, 380009, Ahmedabad, GUJ, India
2
International Center for Cosmology, Charusat University, 388421, Anand, Gujarat, India
3
Department of Mathematics and Statistics, Dalhousie University, NS, B3H 3J5, Halifax, Canada
4
Centre for Theoretical Studies, Indian Institute of Technology, 721302, Kharagpur, West Bengal, India
5
Department of Physics, Rikkyo University, Toshima, 171-8501, Tokyo, Japan
6
Department of Physics, Graduate School of Science, Osaka Metropolitan University, Sugimoto 3-3-138, Sumiyoshi, 558-8585, Osaka, Japan
7
Nambu Yoichiro Institute of Theoretical and Experimental Physics, Osaka Metropolitan University, Sugimoto 3-3-138, Sumiyoshi, 558-8585, Osaka, Japan
Received:
1
November
2023
Accepted:
22
January
2024
Published online:
6
February
2024
The general theory of relativity predicts the relativistic effect in the orbital motions of S-stars which are orbiting around our Milky-way Galactic Center. The post-Newtonian or higher-order approximated Schwarzschild black hole models have been used by GRAVITY and UCLA Galactic Center groups to carefully investigate the S2 star’s periastron precession. In this paper, we investigate the scalar field effect on the orbital dynamics of S2 star. Hence, we consider a spacetime, namely Janis-Newman-Winicour (JNW) spacetime which is seeded by a minimally coupled, mass-less scalar field. The novel feature of this spacetime is that one can retain the Schwarzschild spacetime from JNW spacetime considering zero scalar charge. We constrain the scalar charge of JNW spacetime by best fitting the astrometric data of S2 star using the Monte-Carlo–Markov-Chain (MCMC) technique assuming the charge to be positive. Our best-fitted result implies that similar to the Schwarzschild black hole spacetime, the JNW naked singularity spacetime with an appropriate scalar charge also offers a satisfactory fitting to the observed data for S2 star. Therefore, the JNW naked singularity could be a contender for explaining the nature of Sgr A* through the orbital motions of the S2 star.
© The Author(s) 2024
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