A hybrid model for pulsar's spin-down evolution

By considering the combined effects of both the standard magnetic dipole model and the composite neutron superfluid vortex model on pulsar's spin-down, we study the evolution of pulsar's spin-down on the P - P diagram. The evolution path of each pulsar is dictated by a particular mechanism in our hybrid model within different parameter spaces. The valley of each curve is the most possible place for a neutron star (NS) to be observed as this is the place corresponding to the minimum value of the evolution speed (i.e., the time derivative P). In other words, pulsars would distribute around these valleys on the P - P diagram. The suppressed region in the lower-right part of the diagram can be explained by neutrino cyclotron emission from the S-1(0) neutron superfluid vortexes in NSs.