发表机构
Institute for Research in Fundamental Sciences (IPM); Damghan University; Khazar University; Università di Napoli “Federico II”; Istituto Nazionale di Fisica Nucleare (INFN), sez. di Napoli; Scuola Superiore Meridionale（基础科学研究所; 达姆甘大学; 哈扎尔大学; 那不勒斯费德里科二世大学; 意大利国家核物理研究所（INFN）那不勒斯分部; 南方高等学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文利用S301恒星的自转进动和轨道进动，在强场区域测试PPN参数，打破β-γ简并，精度比太阳系测试高四个数量级。
AI 中文摘要
最近发现的S301恒星，轨道周期为8.7年，偏心率$e = 0.982$，其近心点仅为$140\\,R_{\mathrm{s}}$——比S2的$\sim 1200R_{\mathrm{s}}$近了约九倍——为测试强场引力提供了前所未有的实验室。我们证明，S301的恒星自转进动为PPN参数$\gamma$提供了一种新的探针，其相对于广义相对论（GR）的缩放比例为$(2\gamma_{\mathrm{PPN}} + 1)/3$。对于最大投影速度偏移为$46.1~\mathrm{km\\,s^{-1}}$的情况，下一代光谱仪可将$\gamma_{\mathrm{PPN}}$约束到$\sim 10\\%$的精度。当与S301的轨道进动相结合——每轨道约$\sim 1.95^\circ$的近心点进动（GR预测），比S2的$\sim 0.2^\circ$大约一个数量级，约束$(2\beta_{\mathrm{PPN}} + 2\gamma_{\mathrm{PPN}} - 1)/3$——自转测量打破了$\beta$-$\gamma$简并。对预期的S2和S301观测进行的MCMC分析得出$\sigma_\beta \approx 2.3 \times 10^{-4}$，而$\gamma$的精度受自转进动测量的限制，为$\sigma_\gamma \approx 0.1$。虽然自转进动提供了独立的相容性检验，但其真正意义在于探测$\phi/c^2 \sim 10^{-4}$和$v/c \sim 0.08$处的引力——比太阳系测试强四个数量级，比当前S星约束强一个数量级。这种互补方法为在强场区域测试PPN框架开辟了新窗口，并展示了在银河系中心结合多种恒星探针的威力。
英文摘要
The recently discovered S301 star, with an orbital period of 8.7 years and eccentricity $e = 0.982$, reaches a pericenter of just $140\,R_{\mathrm{s}}$ --- approximately nine times closer than S2's $\sim 1200R_{\mathrm{s}}$ --- offering an unprecedented laboratory for testing strong-field gravity. We demonstrate that S301's stellar spin precession provides a novel probe of the PPN parameter $γ$, scaling as $(2γ_{\mathrm{PPN}} + 1)/3$ relative to general relativity (GR). For maximum projected velocity shifts of $46.1~\mathrm{km\,s^{-1}}$, next-generation spectrographs could constrain $γ_{\mathrm{PPN}}$ to $\sim 10\%$ precision. When combined with S301's orbital precession --- a substantial $\sim 1.95^\circ$ pericenter advance per orbit (GR prediction), approximately an order of magnitude larger than S2's $\sim 0.2^\circ$, constraining $(2β_{\mathrm{PPN}} + 2γ_{\mathrm{PPN}} - 1)/3$ --- the spin measurement breaks the $β$-$γ$ degeneracy. A MCMC analysis of projected S2 and S301 observations yields $σ_β\approx 2.3 \times 10^{-4}$, with the $γ$ precision limited by the spin precession measurement to $σ_γ\approx 0.1$. While the spin precession provides an independent consistency check, its true significance lies in probing gravity at $ϕ/c^2 \sim 10^{-4}$ and $v/c \sim 0.08$ --- four orders of magnitude stronger than Solar System tests and an order of magnitude stronger than current S-star constraints. This complementary approach opens a new window for testing the PPN framework in the strong-field regime and demonstrates the power of combining multiple stellar probes at the Galactic Center.
Comments13 pages (two columns), 4 tables, 4 figures
