Galaxy Rotation Curve Universality Failure

Galaxy rotation curves — the measurement of circular velocity as a function of radius — show a universal tendency to remain flat or even rise slightly beyond the optical disk, inconsistent with the decline expected from the visible stellar and gas mass alone. ΛCDM attributes this flatness to extended dark matter halos of specifically tuned NFW profiles. However, the universality of flat rotation curves across galaxy types and masses, and the precise correlation between the baryonic mass distribution and the rotation curve shape (the Baryonic Tully-Fisher relation and the Radial Acceleration Relation), suggest that the rotation curve shape is fundamentally connected to the baryonic distribution — not an independent dark matter halo coincidentally mirroring it. This fine-tuning requirement is a serious challenge to the ΛCDM dark matter paradigm. Successive Collision Theory explains rotation curve universality through two directly baryonic mechanisms. First, angular momentum inheritance: the collision deposits specific angular momentum per unit mass that scales with position in the debris field, setting a centrifugal barrier that drives the density profile toward ρ(r) ∝ r^{-2} — precisely the profile that produces a flat rotation curve — without requiring any unseen mass.

Second, gravitational superposition from the nested comoving frame hierarchy adds effective gravitational influence that increases the circular velocity at large radii above what the local baryonic mass produces. This superposition term is not an arbitrary addition but a direct consequence of applying GR's superposition principle to the overlapping gravitational wells of the hierarchically nested frames in which every galaxy is embedded. Together, the angular momentum barrier and the frame superposition reproduce flat rotation curves across the full galaxy mass range, and the Radial Acceleration Relation emerges naturally because both effects are functions of the local baryonic surface density — which determines how the angular momentum is distributed and how strongly the local frame couples to the parent hierarchy. The universality of rotation curves across galaxy types is a universal consequence of the collision's angular momentum deposition and the nested frame structure, not a coincidence requiring dark matter halos of carefully tuned profiles for each galaxy.