How Long Spin-Down Needs to Arm a Glitch: Critical-Lag Build Times for Five Pulsars

A glitch can only happen after spin-down has rebuilt the lag that the previous glitch released. This study computes the time needed to build a standard critical fractional lag of 1.2e-4 for five well-timed glitching pulsars, from their published periods and period derivatives, and compares those build times with the pulsars' observed mean intervals between glitches. The full-lag build time is 2.7 years for Vela, 0.30 years for the Crab pulsar, 1.2 years for PSR J0537-6910, 0.4 years for PSR J1119-6127 and 18.0 years for PSR B1737-30. Dividing observed intervals by build times gives the effective lag each pulsar actually accumulates before glitching, from 0.30 of the standard value for J0537-6910 to 1.03 for Vela. Vela alone glitches near the full standard lag; the others release early, which is quantitative evidence that the critical lag is a property of the pinning landscape each star presents, not a universal constant. This study is simulated and computed from stated assumptions; it is not a measurement.