Estimating the Parameters of the Hybrid Palatini Gravity Model with the Schwarzschild Precession of S2, S38 and S55 Stars: Case of Bulk Mass Distribution

Duško Borka,Nenad Đ Lazarov,Violeta N Nikolić,Vesna Borka Jovanović,Predrag Jovanović

doi:10.3390/universe8020070

Duško Borka, Nenad Đ Lazarov + Show 3 more

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https://doi.org/10.3390/universe8020070

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Journal: Universe	Publication Date: Jan 24, 2022
Citations: 4	License type: CC BY 4.0

Affiliation: University of Belgrade, Astronomical Observatory

Abstract

We estimate the parameters of the Hybrid Palatini gravity model with the Schwarzschild precession of S-stars, specifically of the S2, S38 and S55 stars. We also take into account the case of bulk mass distribution near the Galactic Center. We assume that the Schwarzschild orbital precession of mentioned S-stars is the same as in General Relativity (GR) in all studied cases. In 2020, the GRAVITY Collaboration detected the orbital precession of the S2 star around the supermassive black hole (SMBH) at the Galactic Center and showed that it is close to the GR prediction. The astronomical data analysis of S38 and S55 orbits showed that, also in these cases, the orbital precession is close to the GR prediction. Based on this observational fact, we evaluated the parameters of the Hybrid Palatini Gravity model with the Schwarzschild precession of the S2, S38 and S55 stars, and we estimated the range of parameters of the Hybrid Palatini gravity model for which the orbital precession is as in GR for all three stars. We also evaluated the parameters of the Hybrid Palatini Gravity model in the case of different values of bulk mass density distribution of extended matter. We believe that proposed method is a useful tool to evaluate parameters of the gravitational potential at the Galactic Center.

Highlights

In recent decades, various modified gravity theories have appeared as potential extensions of Einstein’s gravity theory [1]
In 2020, the GRAVITY Collaboration detected the orbital precession of the S2 star around the supermassive black hole (SMBH) at the Galactic Center and showed that it is close to the General Relativity (GR) prediction
We give the estimation of parameters of the Hybrid Palatini gravity model by Schwarzschild precession of the S2, S38 and S55 stars, with and without taking into account the bulk mass density distribution of extended matter in the Galactic Center

Summary

Introduction

Various modified gravity theories have appeared as potential extensions of Einstein’s gravity theory [1]. One of the reasons for a postulation of the mentioned theories is the possibility to exclude the concept of dark energy and dark matter and to explain cosmological and astrophysical data collected at different scales considering further degrees of freedom of the gravitational field. This occurs as a consequence of geometric corrections [2]. In [7], the chosen cosmological parameters were determined (as accurate cosmological solutions) within the framework of the represented nonlocal gravitational model, which showed satisfactory agreement with experimental observations

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