Matter-Originated Spacetime Gradient Model (MOSGM): A Phenomenological Gravity Model with Galaxy-Scale Constraints from the SPARC Sample

We present the Matter-Originated Spacetime Gradient Model (MOSGM), a phenomenological modification to baryonic gravitational acceleration motivated by spacetime gradient considerations. The model introduces a bounded interpolating function of the form gₒbs = gbar 1 + κ (μ (x) − 1), where x = √ (gbar/a0), μ (x) = 1/ (1 − e^ (−x) ), and κ = (e − 1) ⁻¹. We evaluate MOSGM using the SPARC dataset of 171 late-type galaxies and compare its performance with the standard MOND algebraic interpolating function under a consistent analysis pipeline. Each model is assessed at its respective optimal stellar mass-to-light ratio: Υdisk = 0. 85 for MOSGM and Υdisk = 0. 50 for MOND. MOSGM achieves a median Pearson correlation of 0. 959 between observed and predicted rotation velocities, compared to 0. 958 for MOND. The median RMS residual is 14. 63 km/s for MOSGM versus 13. 98 km/s for MOND. MOSGM exhibits a near-zero median bias of +0. 20 km/s, compared to +4. 20 km/s for MOND. These results demonstrate that MOSGM reproduces galaxy rotation curves with accuracy comparable to MOND while exhibiting reduced systematic bias. We do not claim that MOSGM supersedes MOND; rather, it provides a competitive alternative framework for galactic dynamics whose phenomenological performance motivates further theoretical development. Notes-This work presents a phenomenological gravity model evaluated on observational data. Theoretical derivation of the interpolating function remains an open area for future work.