Pulsar Glitch Activity in a Strangeon Star Model

Wang, Weihua

Glitch is supposed to be a useful probe into pulsar’s interior, but the underlying physics remains puzzling. The glitch activity may reflect a lower limit of the crustal moment of inertia in conventional neutron star models. Nevertheless, its statistical feature could also be reproduced in the strangeon star model, which is focused here. We formulate the glitch activity of normal radio pulsars under the framework of starquake of solid strangeon star model, the shear modulus of strangeon matter is constrained to be \mu \simeq 3 \times 10^34 erg/cm3 , consistent with previous work. Nevertheless, about ten times the shift in oblateness accumulated during glitch interval is needed to fulfill the statistical observations. The fact that typical glitch sizes of two rapidly evolving pulsars (the Crab pulsar and PSR B0540-69) are about two orders of magnitude lower than that of the Vela pulsar, significantly lower than the oblateness change they can supply, indicates probably that only a part of oblateness change is relieved when a pulsar is young. The unreleased oblateness and stress may relax as compensation in the following evolution. The small glitch sizes and lower glitch activity of the Crab pulsar can be explained simultaneously in our density-dependent two-layered starquake model. Finally, we obtain energy release to be \Delta E~2.4 × 10^40 erg and \Delta E~4.2 \times 10^41 erg for typical glitch size of \Delta\nu/\nu ~ 10^(-6) (Vela-like) and ~10^(-8) (Crab-like).