We analyze galaxy rotation curve data from the SPARC database to investigate whether deviations from the baryonic Tully–Fisher relation (BTFR) are related to internal structural properties. We introduce a dimensionless parameter, K = |∇ρ|/ρ, which quantifies density gradients, and examine its relation to residuals from the BTFR. We find a weak but measurable correlation (r ≈ 0.1), indicating that galaxy dynamics may include subdominant structure-dependent contributions beyond standard one-dimensional scaling. We propose a phenomenological interpretation in which density gradients drive flows that redistribute matter, forming a self-regulating system. Within this framework, galaxies can be viewed as operating between diffuse and structured regimes, with spiral morphology emerging as a manifestation of phase-modulated dynamics. These results suggest that galaxy dynamics are primarily governed by BTFR scaling, with an additional geometric layer linked to internal structure.
Giorgos Vardiampasis (Thu,) studied this question.