Vela's Glitch Budget Under Entrainment: How Much Crust the Activity Really Requires

The Vela pulsar glitches more often and more strongly than any other well-studied pulsar, which makes it the strictest test of where glitch angular momentum is stored. This study recomputes Vela's reservoir requirement from its published timing parameters, a spin frequency of 11.19 Hz and a characteristic age of 1.13e+04 years, together with its long-term glitch activity, and then applies the entrainment discount that band theory imposes on the mobile crustal superfluid. Without entrainment the activity requires 2.00 per cent of the total moment of inertia in the decoupled reservoir. With a mean entrainment of 0.65 the requirement rises to 5.72 per cent, and at 0.90 it reaches 20.01 per cent, beyond what any realistic crust supplies on the sequences examined in this territory. The crust-only model of Vela's glitches therefore survives only if the true average entrainment is modest or if part of the reservoir lies in the core; both possibilities are quantified. This study is simulated and computed from stated assumptions; it is not a measurement.