Unveiling the nature of SgrA* with the geodesic motion of S-stars

TL;DR

This study assesses the potential of future high-precision observations of stars orbiting close to SgrA* to determine whether it is a black hole or a wormhole, finding that closer stars could provide definitive evidence.

Contribution

The paper introduces a methodology to distinguish black holes from wormholes using stellar orbits and demonstrates the observational strategies needed for conclusive identification.

Findings

Current data cannot distinguish black holes from wormholes.

Future observations of stars with ~5-year periods and ~5 AU pericenters could identify the nature at 5σ.

Mock data analysis confirms the methodology's effectiveness.

Abstract

Despite the huge improvements guaranteed by future GRAVITY observations of the S0-2 star, these will not be able to unveil the fundamental nature, whether black hole or wormhole, of the central supermassive object. Nevertheless, observing stars orbiting closer to the central gravitational source could allow to distinguish between the black hole and wormhole nature of this object at more than 5$\sigma$. Firstly, we have used publicly available astrometric and spectroscopic measurements of the S0-2 star to constrain the metric around the supermassive object without finding any evidence either favouring or ruling out the wormhole nature. Secondly, we have designed a mock catalogue of future observations of the S0-2 star mirroring the accuracy and precision of GRAVITY. Afterwards, we firstly tested our methodology showing that our procedure recovers the input model, and subsequently we demonstrated that the constraining power of such a dataset is not enough to distinguish between black hole and wormhole. Finally, we built some toy models representing stars orbiting much closer the central object than S0-2. We used these toy models to investigate which are the ideal orbital features and observational strategies to achieve our aim of unveiling the fundamental nature of the central supermassive object, demonstrating that a star with a period of the order of $\sim 5$ years and a pericentre distance of $\sim 5$ AU could identify the nature of the central object at almost 5$\sigma$ accuracy.