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

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 (less than or similar to 10(5) 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 similar to 10(12) G and initial spin period similar to 0.1-0.2 s accretion rate greater than or similar to 10(14)-10(15) g s(-1) is enough to avoid the Ejector stage.

Automated summary

Recently, several accreting neutron stars inside supernova remnants have been discovered. Their ages are much shorter than expected, which poses a puzzle for the standard magnetorotational evolution of neutron stars. By considering early fallback accretion and asymmetry in the transitions between different evolutionary stages, this study provides an explanation for the appearance of these systems.