Year: 2026
Type: preprint
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 $Λ\lesssim 6.9\times10^{-48}\mathrm{m}^{-2}$ at 68\% credibility and $Λ\lesssim 1.0\times10^{-38}\mathrm{m}^{-2}$ at 95\% credibility. The 68\% constraint is the strongest bound at a comparable dynamical timescale.
Source: arXiv (Cornell University)
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Award: G2230720350
OpenAlex ID: W7164555430