Formation of neutron stars via accretion-induced collapse and core-merger-induced collapse inside planetary nebulae from white dwarf binaries
The accretion-induced collapse (AIC) and core-merger-induced collapse (CMIC) from oxygen-neon-magnesium (ONeMg) white dwarf (WD) binaries inside planetary nebulae (PNe) have not been previously even mentioned in the literature. In this paper, I propose and study two possible WD binary channels for AIC and CMIC to form neutron stars (NSs) within PNe. First, using simulations performed with the \textsc{MESA} stellar evolution code, I present a scenario in which NSs form via the AIC of ONeMg WDs inside PNe--referred to here as symbiotic nebulae. In the late evolutionary stages of ONeMg WD-red giant (or asymptotic giant branch) star binaries, substantial mass loss can occur through strong stellar winds or/and Roche-lobe overflow, potentially leading to the formation of nebulae surrounding central accreting WD binaries. These nebulae may be ionized by the hot cores of the giant stars or by the accreting WDs themselves. Under such conditions, the accreting WD may grow in mass to the Chandrasekhar limit and undergo collapse into a neutron star. NSs formed via this AIC channel are likely to retain WD companions, resulting in NS-WD binary systems, of which the Milky Way may host dozens. Second, through binary population synthesis modeling, I introduce another evolutionary pathway: the CMIC occurring during the common envelope evolution of ONeMg WD binaries. This process may result in the formation of a newborn NS within a PN -or, in some cases, a pulsar wind nebula.