Wetro, Legesse (PhD)Merid, Asfaw2018-06-182023-11-092018-06-182023-11-092013-06http://10.90.10.223:4000/handle/123456789/1405A neutron star core super uid rotates at a di erent rate to that of the crust, while spinning down at the same steady-state rate as the rest of the star, because of the assumed pinning between the super uid vortices and the inner crust. We nd that the magnitude of this rotational lag changes with time and also depends on the distance from the rotation axis; the core super uid supports an evolving pattern of di erential rotation. We predicted change of the lag might occur as discrete events which could result in a sudden rise of the spin frequency of the crust of a neutron star, as is observed in glitches in radio pulsars. Glitches are believed to have been caused by break aways of pinned vortices.This new possibility for the triggering cause of glitches in radio pulsars is further supported by an estimate of the total predicted excess angular momentum reservoir of the core super uid. The model seems to o er resolutions for some other aspects of the observational data on glitches. The goal of this project is to show the tidal force e ect on the di erential motion of the crust with respect to the core of the neutron star could lead to the reduction of glitch frequencies and eventually produced gravitational locking between the core and the crust of a neutron starenThe Crust of Neutron StarTidal Force and Torque on the Crust of Neutron StarThesis