强磁场对中子星转动惯量与表面引力红移的影响

Effects of strong magnetic field on moment of inertia and surface gravitational redshift in neutron star

开展强磁场环境下中子星物质性质的研究对约束中子星物态方程,揭示星体内部磁场分布形式等有重要意义.本文基于相对论平均场理论利用GL91参数组研究了处于β平衡条件下传统中子星物质在强磁场作用下的主要宏观性质.结果表明,强磁场的引入使传统中子星物态方程变硬,星体质量上限由2.111 M_(⊙)增大到3.081 M_(⊙),相同质量星体对应的半径变大使星体变得不那么致密;强磁场对传统中子星表面引力红移有抑制作用,对转动惯量有促进作用.此外,给出了目前已观测到的四颗大质量脉冲星-PSRs J1614-2230,J0348+0432,J0740+6620,J2215-5135,以及双星合并事件GW190814中质量在2.50 M_(⊙)-2.67 M_(⊙)的致密星体表面引力红移和转动惯量的理论值范围.结果表明,随着中子星内部磁场的增强,这五颗星的表面引力红移值范围变窄,而转动惯量的范围变宽.

Research on the properties of neutron stars with strong magnetic fields is of great significance in constraining the equation of state and revealing the real distribution of magnetic fields in neutron stars.The main macroscopic properties of the traditional neutron star matter under β equilibrium condition are studied within the relativistic mean field theory through using the GL91 parameter set by considering the strong magnetic field.It is found that the onset of the strong magnetic field leads to the stiffened equation of state of the traditional neutron star matter.The maximum mass of the traditional neutron star grows from 2.111 M_(⊙)to 3.081 M_(⊙),the radius of the fixed mass traditional neutron star grows larger with the increase of internal magnetic field,which makes traditional neutron star become less dense.The strong magnetic field can also reduce the surface gravitational redshift and strengthen the moment of inertia of the traditional neutron star matter.In addition,the theoretical ranges of the surface gravitational redshift and the moment of inertia for the four massive PSRs J1614-2230,J0348+0432,J0740+6620 and J2215-5135,and the 2.50 M_(⊙)−2.67 M_(⊙)compact object in the binary merger event GW190814 are also given.The results show that the ranges of the surface redshift become narrower,while the scopes of the moment of inertia widen as the magnetizing field increases in the five stars.