Ridolfi A, Freire P C C, Gupta Y, Ransom S M
Max Planck Institute for Radio Astronomy, Auf dem Hugel 69, D-53121 Bonn, Germany.
INAF - Osservatorio Astronomico di Cagliari, Via della Scienza 5, I-09047 Selargius (CA), Italy.
Mon Not R Astron Soc. 2019 Dec;490(3):3860-3874. doi: 10.1093/mnras/stz2645. Epub 2019 Sep 25.
In this work, we present the results of 1 yr of upgraded Giant Metrewave Radio Telescope timing measurements of PSR J0514-4002A, a 4.99-ms pulsar in a 18.8-d eccentric ([Formula: see text]) orbit with a massive companion located in the globular cluster NGC 1851. Combining these data with earlier Green Bank Telescope data, we greatly improve the precision of the rate of advance of periastron, [Formula: see text] which, assuming the validity of general relativity, results in a much refined measurement of the total mass of the binary, [Formula: see text]. Additionally, we measure the Einstein delay parameter, γ, something that has never been done for any binary system with an orbital period larger than [Formula: see text]10 h. The measured value, [Formula: see text], is by far the largest for any binary pulsar. Furthermore, we measure the proper motion of the system ([Formula: see text] and [Formula: see text]), which is not only important for analysing its motion in the cluster, but is also essential for a proper interpretation of γ, given the latter parameter's correlation with the variation of the projected semimajor axis. The measurements of γ and the proper motion enable a separation of the system component masses: we obtain a pulsar mass of [Formula: see text] and a companion mass of [Formula: see text]. This raises the possibility that the companion is also a neutron star. Searches for radio pulsations from the companion have thus far been unsuccessful; hence, we cannot confirm the latter hypothesis. The low mass of this millisecond pulsar - one of the lowest ever measured for such objects - clearly indicates that the recycling process can be achieved with a relatively small amount of mass transfer.
在这项工作中，我们展示了对PSR J0514 - 4002A进行1年升级后的巨型米波射电望远镜计时测量结果。PSR J0514 - 4002A是一颗周期为4.99毫秒的脉冲星，位于球状星团NGC 1851中，其轨道偏心率为18.8天（[公式：见原文]），并伴有一个大质量伴星。将这些数据与早期绿岸望远镜的数据相结合，我们极大地提高了近日点进动速率[公式：见原文]的精度，假设广义相对论成立，这使得对双星总质量[公式：见原文]的测量更加精确。此外，我们测量了爱因斯坦延迟参数γ，对于任何轨道周期大于[公式：见原文]10小时的双星系统，此前从未有过这样的测量。所测值[公式：见原文]是所有双星脉冲星中迄今为止最大的。此外，我们测量了该系统的自行（[公式：见原文]和[公式：见原文]），这不仅对于分析其在星团中的运动很重要，而且鉴于后一个参数与投影半长轴变化的相关性，对于正确解释γ也至关重要。对γ和自行的测量使得能够分离系统的组分质量：我们得到脉冲星质量为[公式：见原文]，伴星质量为[公式：见原文]。这增加了伴星也是一颗中子星的可能性。迄今为止，对伴星的射电脉冲搜索尚未成功；因此，我们无法证实后一种假设。这颗毫秒脉冲星的低质量——是此类天体中测量到的最低质量之一——清楚地表明，相对少量的质量转移就能实现再循环过程。
