Improving constraints on the Yukawa correction at the Galactic Center with multiple stellar orbits

Abstract

We investigate the presence of a Yukawa-like correction ($\propto \alpha e^{-r/\lambda }$) to Newtonian gravity at the Galactic Center, using a multi-star fitting code, including the newly discovered star S$301$, to improve the constraints obtained using S$2$ orbit alone. We perform a Markov Chain Monte Carlo analysis using the astrometric and spectroscopic data of stars S$2$, S$55$, S$29$, S$38$ and S$301$ collected by GRAVITY, GRAVITY${}^{+}$, NACO and SINFONI instruments, covering the period from $1992$ to $2025$. Compared to GRAVITY Collaboration 2025 (Paper I), in which only S$2$ was fitted, the tightest bound on the Yukawa coupling is again reached at $\lambda =3\cdot 10^{13}\mathrm{m}(\sim 200\mathrm{AU})$, where we find $|\alpha |<6\cdot 10^{-4}$, an improvement of roughly a factor five. The addition of S$301$ extends the constraint to short ranges that were inaccessible to S$2$, yielding $|\alpha |<0.004$ at $\lambda =10^{12}\mathrm{m}$ and $|\alpha |<0.006$ at $\lambda =5\cdot 10^{11}\mathrm{m}$, while S$29$, with its larger apoapsis, gives $|\alpha |<0.1$ at $\lambda \sim 2\cdot 10^{15}\mathrm{m}$. The latter two represent the tightest limits at these scale lengths on a Yukawa correction obtained to date around a supermassive black hole.

9 pages, 4 figures. Submitted to A&A