On the lack of X-ray pulsation in most neutron star low-mass X-ray binaries

Niang N., Ertan Ü., Gençali A., Toyran O., ULUBAY A., Devlen E., ...Daha Fazla

Monthly Notices of the Royal Astronomical Society, cilt.532, sa.2, ss.2133-2142, 2024 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 532 Sayı: 2
  • Basım Tarihi: 2024
  • Doi Numarası: 10.1093/mnras/stae1595
  • Dergi Adı: Monthly Notices of the Royal Astronomical Society
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Applied Science & Technology Source, Communication Abstracts, Compendex, INSPEC, Metadex, zbMATH, DIALNET, Civil Engineering Abstracts
  • Sayfa Sayıları: ss.2133-2142
  • Anahtar Kelimeler: accretion, accretion discs, stars: neutron
  • İstanbul Üniversitesi Adresli: Evet

Özet

We have investigated whether the lack of X-ray pulsations from most neutron star (NS) low-mass X-ray binaries (LMXBs) could be due to the extension of their inner disc to the NS surface. To estimate the inner disc radii, we have employed the model, recently proposed to account for the torque reversals of LMXBs. In this model, the inner disc radius depends on the spin period as well as the dipole moment and the mass inflow rate of the disc. Our model results indicate that most LMXBs have mass accretion rates above the minimum critical rates required for the inner disc to reach down to the NS surface and thereby quench the pulsed X-ray emission. For most sources X-ray pulsations are allowed when the period decreases below a certain critical value. For the same parameters, the model is also consistent with the observed X-ray luminosity ranges of the individual accreting millisecond X-ray pulsars (AMXPs). The paucity of AMXPs compared to the majority population of non-pulsing LMXBs is explained, as well as the fact that AMXPs are transient sources.