A Universal Inertial Correction (ΦKβ) with 97.7% Success on Galactic Rotation Curves from the SPARC Database

This work introduces an alternative dynamical model for galaxies, based on the hypothesis of cosmic inertial drag, expressed through a universal corrective factor of the form (1−α⋅RRmax)(1 - \alpha \cdot \frac{R}{R_{\text{max}}})(1−α⋅RmaxR), applied to the theoretical baryonic rotation velocity VbV_bVb. The model relies exclusively on known baryonic components (gas, disk, bulge) from the SPARC database, without introducing dark matter. By combining these components quadratically and modulating them with the ΦKβ factor, it becomes possible to reproduce observed galactic rotation curves with remarkable accuracy. With a single universal constant, α=0.01180\alpha = 0.01180α=0.01180, applied identically across all galaxies tested, the model outperforms Λ-CDM in 97.14% of cases over a sample of 175 SPARC galaxies, according to the root mean square error (RMSE) criterion. These results suggest that an inertial coupling between baryons and the cosmological vacuum may be sufficient to explain galactic rotation curves, without invoking dark matter or modifying Newtonian gravity.