Bounds on at the Galactic Center
gr-qc, astro-ph.CO
Submitted: 2026-06-11
Updated: 2026-09-17
Comments: 27 pages, 9 figures
License: http://creativecommons.org/licenses/by/4.0/
The gist: We constrain the cosmological constant, Λ, using astrometric and spectroscopic observations of the S2 star, supplemented by S1 and S14 stars orbiting Sgr A*.
Terminology
Abstract
We constrain the cosmological constant, Λ, using astrometric and spectroscopic observations of the S2 star, supplemented by S1 and S14 stars orbiting Sgr A*. We develop a framework for modelling relativistic stellar orbits in general spherically symmetric spacetimes and perform Bayesian parameter estimation to jointly infer orbital and spacetime parameters. Applying this framework to Schwarzschild-de Sitter spacetime, we obtain upper bounds on Λ. The individual constraints exhibit the expected dependence on the dynamical timescales of the stars, with the longer-period S1 providing the strongest sensitivity. Combining the individual constraints, we obtain Λ 6.9 times10-48 m-2 at 68% credibility and Λ 1.0 times10-38 m-2 at 95% credibility. The 68% constraint is the strongest bound at a comparable dynamical timescale.
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