The Influence Of Strong Magnetic Fields On Bulk Properties Of Neutron Star

In the frame work of the relativistic mean field theory(RMFT), strong magnetic field, the particle fractions in theneutron star matter, the equation of state, and bulk properties ofneutron stars with strong magnetic field are studied. Thenumerical show that strong magnetic fields have an importantinfluence the particle fractions. In strong magnetic fields, Protondensity increases with the increasing of total baryon densities,while neutron number density decreases. When the total baryonnumber density is about 6 ρ 0, neutrons and protons almost havethe equal proportion, which leads to the symmetric nuclear matter.This is because the introduction of the strong magnetic fieldmakes that the chemical potential for nucleon and lepton changegreatly, which help the β decay process from neutrons to protonshappens more easily, and it enhances the proton number densityand reduces the neutron number density. This result will have aprofound influence upon the evolvement of neutron-proton stars. Strong magnetic fields also influence the equation of stateand the bulk properties of the neutron star. As the magnetic fieldincreasing, the equation of state becomes stiffer. So themaximum mass of the neutron star becomes bigger. However,this change is not very obvious. For neutron star matter includingneutron, proton and lepton, the maximum mass still stays about2M⊙.The anomalous magnetic moments (AMM) of both protonand electron are incorporated in this paper. It is found that in therelative weak magnetic field the AMM can suppress the effectthat proton number density increases and neutron numberdecreases. In the relative strong magnetic field, however theAMM can't influence the particle fractions obviously. In thesame magnetic field, the equation of state with the anomalousmagnetic moments are taken into account is stiffer than the onewithout AMM. However, the influences of this change on therelation of the star's mass and radius are almost negligible.