On the bottom spin period and magnetic field of millisecond pulsar

Abstract

The spin frequency of millisecond pulsar (MSP) is spun up in its binary accretion phase, while its magnetic field decays. The neutron star magnetic field has little decay if there is no accretion happened. The MSP magnetic field will arrive at a bottom value of about 108 G, if the system accretes about 20% solar mass, which corresponds to that the neutron star magnetosphere radius matches the star radius. The MSP spin period will arrive at a bottom value of about 1.5 millisecond if the bottom field is arrived, and this bottom period is independent of the initial period and initial magnetic field, which hints that MSPs and accretion‐powered X‐ray pulsars are homogeneous objects in their spin frequencies if they accreted the similar weight of matter.