Observable Spin Precession Induced by a Scalar Time Field in Strong Gravitational Regimes

Recent phenomenological models have proposed a scalar time-rate field T(x) as an effective ge ometric alternative to particle dark matter, successfully reproducing galactic rotation curves and cluster dynamics. In this work, we demonstrate that the spatial gradients of this field induce a novel, universal spin precession effect. Guided by symmetry and dimensional analysis, we derive the effective equation of motion for intrinsic spin in the presence of ∇T, showing that it acts anal ogously to Larmor precession but sourced purely by the local gravitational acceleration. Applying this framework to compact astrophysical objects, we find that a naive O(1) coupling would produce millisecond-scale precession, which is strongly excluded by pulsar timing data. By comparing our prediction with the observed geodetic spin precession of the Double Pulsar (PSR J0737−3039), we place a stringent upper bound on the spin-sector coupling constant, κ ≲ 10−12. This constraint validates the model’s consistency with current observations and provides a critical quantitative tar get for future fundamental theories (such as Einstein–Cartan gravity) to explain the dynamical suppression of this effect in the infrared regime.