2020/02/28 by Zhu-Ling Deng, Zhi-Fu Gao, Xiang-Dong Li +1 · 1 citation
Physics and Astronomy · #astro-ph.HE #astro-ph.SR
paper · pdf · doi:10.3847/1538-4357/ab76c4
24 pages, 5 figures, accepted for publication in ApJ
arxiv created 2020/02/28 · arxiv updated 2020/03/25
PSR J1640+2224 is a binary millisecond pulsar (BMSP) with a white dwarf (WD) companion. Recent observations indicate that the WD is very likely to be a ∼ 0.7 M\odot CO WD. Thus the BMSP should have evolved from an intermediate-mass X-ray binary (IMXB). However, previous investigations on IMXB evolution predict that the orbital periods of the resultant BMSPs are generally <40 days, in contrast with the 175 day orbital period of PSR J1640+2224. In this paper, we explore the influence of the mass of the neutron star (NS) and the chemical compositions of the companion star on the formation of BMSPs. Our results show that, the final orbital period becomes longer with increasing NS mass, and the WD mass becomes larger with decreasing metallicity. In particular, to reproduce the properties of PSR J1640+2224, the NS was likely born massive (>2.0 M\odot).