几何因素对脉冲星自转参数的影响

The Effect of Geometrical Factors on Pulsar Rotation Parameters

脉冲星自转参数是脉冲星最重要的参数之一,能反映脉冲星本身的物理性质.根据计时观测所得的自转参数除了包含脉冲星本身固有的部分,还受到几何因素的影响,例如地球自转参数、岁差章动模型、行星历表误差、脉冲星相对于太阳系质心(solar system barycenter,SSB)的速度和加速度.通过分析脉冲星计时观测模型,从而推导出这些因素与脉冲星自转参数的关系,进一步估计了这些因素对自转参数影响的量级大小.在现有的观测精度下,地球自转参数和岁差章动模型的误差对计时观测的影响可忽略,可以认为脉冲星自转参数不受其影响.行星历表误差对自转参数的影响远小于自转参数本身,同样可以忽略.脉冲星相对于太阳系质心的视向速度影响到脉冲星周期,该影响比脉冲星本身周期约小4个量级.值得注意的是,脉冲星横向速度和脉冲星相对于太阳系质心的视向加速度对周期变率的影响不可忽略,特别是对于周期变率较小的毫秒脉冲星来说,这两个因素的影响可能是脉冲星视周期变率中的主要成分.

This paper presents a detailed investigation of the effects of geometrical factors on pulsar rotation parameters, such as the Earth orientation parameters, precession-nutation model, relative velocity, relative radial acceleration, and planetary ephemeris error. We derive the magnitude of the effect of secular variations in the observed periods and period derivatives, assuming that pulsars have typical values of the parameters. The effects of Earth orientation parameters and precession-nutation model are neglected at the current accuracy level of observation. Furthermore, the planetary ephemeris error has a marginal effect on the pulsar period parameters, and the effect of relative radial velocity is also ignored. tire radial acceleration stand as the likely However, the transverse velocity and relasources of period derivative, especially for millisecond pulsars, where they may dominate the observed value of period derivative