English

Gravitational Anomaly Measurement in Wide Binaries is Sensitive to Orbital Modeling

Solar and Stellar Astrophysics 2026-03-12 v1 Astrophysics of Galaxies Instrumentation and Methods for Astrophysics

Abstract

Recent work by Chae et al. (2026) reported a gravitational anomaly in 36 wide-binary pairs, finding a gravity boost factor of γGeff/GN1.600.14+0.17\gamma \equiv G_{\rm eff}/G_{\rm N} \approx 1.60_{-0.14}^{+0.17} at low accelerations, consistent with predictions from Modified Newtonian Dynamics (MOND). We reanalyze the same dataset using a hierarchical Bayesian model that infers a global γ\gamma across all systems while fitting three-dimensional orbital elements. Our model yields γ=1.120.22+0.27\gamma = 1.12^{+0.27}_{-0.22}, consistent with Newtonian gravity (γ=1\gamma = 1) at the 0.4σ\sim0.4\sigma level. To identify the source of the discrepancy, we perform a test using an approach similar to Chae et al. (2026), replacing the semi-major axis with a geometric de-projection of the observed projected separation. This test yields γ=1.560.18+0.21\gamma = 1.56^{+0.21}_{-0.18}, closely matching the result of Chae et al. (2026). This suggests that the inferred value of γ\gamma is sensitive to how the three-dimensional orbital separation is modeled, and including an independent semi-major axis parameter can account for velocity excesses that would otherwise be attributed to non-Newtonian gravity.

Keywords

Cite

@article{arxiv.2603.11015,
  title  = {Gravitational Anomaly Measurement in Wide Binaries is Sensitive to Orbital Modeling},
  author = {Serat M. Saad and Yuan-Sen Ting},
  journal= {arXiv preprint arXiv:2603.11015},
  year   = {2026}
}

Comments

10 pages, 4 figures. Submitted to OJAp