Origin of young accreting neutron stars in high-mass X-ray binaries in supernova remnants

Abstract

ABSTRACT Recently, several accreting neutron stars (NSs) in X-ray binary systems inside supernova remnants have been discovered. They represent a puzzle for the standard magnetorotational evolution of NSs, as their ages (≲105 yr) are much shorter than the expected duration of Ejector and Propeller stages preceding the onset of wind accretion. To explain appearance of such systems, we consider rotational evolution of NSs with early fallback accretion and asymmetry in forward/backward transitions between Ejector and Propeller stages (so-called hysteresis effect proposed by V. Shvartsman in 1970). It is shown that after a successful fallback episode with certain realistic values of the initial spin period, stellar wind properties, and magnetic field, a young NS may not enter the Ejector stage during its evolution which results in a relatively rapid initiation of accretion within the lifetime of a supernova remnant. For a standard magnetic field ∼1012 G and initial spin period ∼0.1–0.2 s accretion rate ≳1014–1015 g s−1 is enough to avoid the Ejector stage.