Emergent Galactic Dynamics from Finite-Response Media: A Coherence-Based Origin of the Tully–Fisher Relation

Modified Newtonian Dynamics (MOND) provides an empirical description of galactic rotation curves and the baryonic Tully–Fisher relation, but lacks a widely accepted underlying physical mechanism. In this work, we derive MOND-like scaling within the Emergent Condensate Superfluid Medium (ECSM) framework, in which gravitational and inertial effects arise from finite-response dynamics of an underlying medium. A coherence-dependent transition from volumetric to shell-dominated response leads to an effective suppression of inertial coupling at low accelerations, producing the scaling a ~ sqrt(a_N a_0) and recovering the Tully–Fisher relation v^4 = G M a_0. The characteristic acceleration scale a_0 emerges naturally from medium properties as a_0 ~ c_eff / tau_resp, providing a physical interpretation of MOND phenomenology. This work presents a mechanism-based explanation for MOND scaling and suggests a pathway toward resolving its known limitations.