2026ApJ...997..265N -
Astrophys. J., 997, 265 (2026/February-1)
Formation of Recycled Pulsars in Common Envelope Binaries.
NIE Y.-D., SHAO Y., HE J.-G., WEI Z.-L., GAO S.-J., XU X.-J. and LI X.-D.
Abstract (from CDS):
We present a systematic study of the evolution of low- and intermediate-mass X-ray binaries consisting of a 1.4 M⊙ neutron star (NS) and a donor star of mass 1-8 M⊙. Using grids of detailed MESA simulations, we show that for donor masses of 2-8 M⊙, mass transfer may be dynamically unstable, leading to a common envelope (CE) phase. By adopting CE ejection efficiencies in the range αCE = 0.3-3.0, we find that post-CE binaries frequently experience a CE decoupling phase (CEDP), which plays a critical role in determining their final orbital and compositional properties. Systems with initial donor masses ≳3.5 M⊙ predominantly evolve into NS binaries with carbon-oxygen or oxygen-neon white dwarfs (WDs) with masses between 0.5 and 1.4 M⊙. Comparison with the observed population of binary pulsars with a WD companion shows better agreement with higher CE ejection efficiencies (αCE = 3.0). Furthermore, we demonstrate that NSs can accrete a sufficient amount of matter (≳0.01 M⊙) during the CEDP and subsequent Case BA/BB/BC mass transfer phases to be effectively recycled into millisecond pulsars. We identify two distinct evolutionary channels capable of reproducing the observed characteristics of the millisecond pulsar PSR J1928+1815 with a helium-star companion. Our results highlight the importance of the CEDP in the formation of recycled pulsars and provide constraints on the CE ejection efficiency during binary evolution.
Abstract Copyright:
© 2026. The Author(s). Published by the American Astronomical Society.
Journal keyword(s):
Binary stars - X-ray binary stars - Neutron stars - White dwarf stars - Stellar evolution
Simbad objects:
2
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