Comparing timelike geodesics around a Kerr black hole and a boson star

Abstract

The second-generation beam combiner at the Very Large Telescope (VLT), GRAVITY, observes the stars orbiting the compact object located at the center of our galaxy, with an unprecedented astrometric accuracy of 10 $\mu$as. The nature of this compact source is still unknown since black holes are not the only candidates explaining the four million solar masses at the Galactic center. Boson stars are such an alternative model to black holes. This paper focuses on the study of trajectories of stars orbiting a boson star and a Kerr black hole. We put in light strong differences between orbits obtained in both metrics when considering stars with sufficiently close pericenters to the compact object, typically $\lesssim 30M$. Discovery of closer stars to the Galactic center than the S2 star by the GRAVITY instrument would thus be a powerful tool to possibly constrain the nature of the central source.

30 pages, 20 figures

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Cited by in corpus (22)

• The imitation game: Proca stars that can mimic the Schwarzschild shadow
• Rotating Axion Boson Stars
• Circular Orbits Structure and Thin Accretion Disks around Kerr Black Holes with Scalar Hair
• Extreme-mass-ratio inspirals into rotating boson stars: nonintegrability, chaos, and transient resonances
• Static spheres around spherically symmetric black hole spacetime
• The Galactic Center as a laboratory for theories of gravity and dark matter
• Proca-Higgs balls and stars in a UV completion for Proca self-interactions
• On the Structure of Rotating Charged Boson Stars
• Stability and physical properties of spherical excited scalar boson stars
• Retrograde Polish Doughnuts around Boson Stars
• Rotating tensor-multi-scalar solitons
• General formulae for the periapsis shift of a quasi-circular orbit in static spherically symmetric spacetimes and the active gravitational mass density
• Self-interactions can (also) destabilize bosonic stars
• Magnetized Thick Disks around Boson Stars
• Static spheres and Aschenbach effect for black holes in massive gravity
• Fate of initially bound timelike geodesics in spherical boson stars
• Equatorial orbits of spinning test particle in rotating boson star
• Stability and collisions of excited spherical boson stars: glimpses of chains and rings
• Tidal Disruption of Stars by Supermassive Black Holes and Naked Singularities with Scalar Hair
• Extended mass and spheroidal deformation effects on epicyclic frequencies and periapsis shift in quasi-circular orbits
• There and back again: Outspiraling motion in non-Kerr compact objects
• Topological charge and black hole photon spheres in massive gravity