The Vortex Pinning Force Across the Inner Crust and the Largest Lag It Can Hold

Vortex pinning is the microscopic mechanism that lets a neutron-star crust store angular momentum and release it in glitches, and its strength varies by orders of magnitude across the crust. This study computes the pinning force per unit vortex length as a function of density through the inner crust using a stated layer model calibrated to published mesoscopic pinning calculations. The force peaks at 4.0e+12 N per metre at a density of 6.0e+16 kg per cubic metre and falls to 6.4e+05 N per metre in the outermost inner crust. Balancing the pinning force against the Magnus force gives a maximum sustainable velocity lag of 481.5 m per second, corresponding to a fractional spin lag of 5.7e-04 for a Vela-like star. Layers below about 8.7e+15 kg per cubic metre contribute pinning too weak to hold the lag that giant glitches require, which concentrates the effective reservoir in the deeper crust. This study is simulated and computed from stated assumptions; it is not a measurement.