Asymmetric Kinetic Feedback from Core-Collapse Supernovae as a Structural Delay Margin in Spiral Arms

The "winding problem" — the theoretical rapid dissolution of material spiral arms under differential galactic rotation — remains incompletely resolved. This paper quantitatively evaluates two candidate baryonic braking mechanisms associated with stellar-mass black holes (BHs) and core-collapse supernovae (SNe) in spiral arms. Throughout, the winding problem is formulated rigorously in terms of the kinematic shear torque tau_wind = M_arm * r2 * Delta_Omega2 = 2.04e48 N m, and all efficiency ratios are computed as tau_ejecta / tau_wind. First, we demonstrate rigorously that the transient gravitational drag (Chandrasekhar dynamical friction) of BHs passing through the arm is negligible, with an efficiency eta < 10-6 relative to the kinematic shear torque tau_wind = 2.04e48 N m. Second, we identify a physically valid baryonic braking mechanism: the "Champagne Flow" effect of SN ejecta. Due to the density gradient between the arm interior and the inter-arm void, SN ejecta expands asymmetrically — inward ejecta impacts the dense arm material and is rapidly decelerated, while outward ejecta escapes freely into the low-density void. This asymmetry generates a continuous, dissipative, tangential counter-torque. We calculate that this mechanism provides a structural delay margin of approximately 1-12% (fiducial ~6% for f_asym = 5%)t per Gyr. We further propose the "Differential Maintenance Hypothesis": since the Champagne Flow feedback is proportional to the local SN rate (itself proportional to the local SFR), arms with higher star-formation activity are dynamically hardened, while quiescent arm segments shear faster, transitioning to flocculent morphologies and spurs. This prediction is consistent with JWST observations of non-uniform arm degradation within individual galaxies.