Donors of Persistent Neutron-star Low-mass X-ray Binaries

TL;DR

This study uses population synthesis to analyze the properties and formation channels of donors in persistent neutron-star low-mass X-ray binaries, revealing main sequence donors dominate and different formation pathways for various donor types.

Contribution

It provides a detailed population synthesis analysis of donors in persistent neutron-star LMXBs, highlighting their formation channels and donor type distributions.

Findings

Over 90% of PLMXBs have main sequence donors.

PLMXBs with red giant donors via stellar wind are negligible.

Most neutron stars in PLMXBs with hydrogen-rich donors form via core-collapse supernovae.

Abstract

Properties of X-ray luminosities in low-mass X-ray binaries (LMXBs) mainly depend on donors. We have carried out a detailed study of donors in persistent neutron-star LMXBs (PLMXBs) by means of a population synthesis code. PLMXBs with different donors have different formation channels. Our numerical simulations show that more than 90% of PLMXBs have main sequence (MS) donors, and PLMXBs with red giant (RG) donors via stellar wind (Wind) are negligible. In our model, most of neutron stars (NSs) in PLMXBs with hydrogen-rich donors form via core-collapse supernovae, while more than 90% of NSs in PLMXBs with naked helium star (He) donors or white dwarf (WD) donors form via an evolution-induced collapse via helium star ($1.4 \leq M_{\rm He}/M_\odot \leq 2.5$) or an accretion-induced collapses for an accreting ONeMg WD.