Evolving ONe WD+He star systems to intermediate-mass binary pulsars

TL;DR

This study explores the evolution of ONe WD+He star systems as a pathway to form intermediate-mass binary pulsars, successfully explaining most observed systems with short orbital periods and providing insights into their formation mechanisms.

Contribution

It presents a comprehensive simulation of about 900 ONe WD+He star binaries, expanding understanding of IMBP formation and matching observed pulsar parameters.

Findings

The scenario can produce IMBPs with 5-340 ms spin periods and 0.75-1.38 Msun WD companions.

Most observed IMBPs with short orbital periods are explained by this scenario.

The model matches parameters of PSR J1802-2124 and suggests the companion of HD 49798 may not be a neutron star.

Abstract

It has been suggested that accretion-induced collapse (AIC) is a non-negligible path for the formation of the observed neutron stars (NSs). An ONe white dwarf (WD) that accretes material from a He star may experience AIC process and eventually produce intermediate-mass binary pulsars (IMBPs), named as the ONe WD+He star scenario. Note that previous studies can only account for part of the observed IMBPs with short orbital periods. In this work, we investigate the evolution of about 900 ONe WD+He star binaries to explore the distribution of IMBPs. We found that the ONe WD+He star scenario could form IMBPs including pulsars with 5-340 ms spin periods and 0.75-1.38 Msun WD companions, in which the orbital periods range from 0.04 to 900 d. Compared with the 20 observed IMBPs, this scenario can cover the parameters of 13 sources in the final orbital period-WD mass plane and the Corbet diagram, most of which has short orbital periods. We found that the ONe WD+He star scenario can explain almost all the observed IMBPs with short orbital periods. This work can well match the observed parameters of PSR J1802-2124 (one of the two precisely observed IMBPs), providing a possible evolutional path for its formation. We also speculate that the compact companion of HD 49798 (a hydrogen depleted sdO6 star) may be not a NS based on the present work.