Wide binary pulsars from electron-capture supernovae

ABSTRACT Neutron stars receive velocity kicks at birth in supernovae. Those formed electron-capture supernovae from superasymptotic giant branch – the lowest mass to end their lives may significantly lower than typical neutron stars. Given that many massive are members of wide binaries, this suggests existence a population low-mass (1.25 < Mpsr/M⊙ 1.3), (Porb ≳ 104 d), eccentric (e ∼ 0.7), unrecycled (Pspin 1 s) binary pulsars. The formation rate such binaries is sensitive range (effectively) single leading electron capture supernovae, amount lost prior supernova, and magnitude any natal kick imparted on star. We estimate one pulsar should be observable Milky Way for every 10 000 isolated pulsars, assuming width ≲0.2 M⊙, less km s−1. have searched catalogue observed but find no convincing candidates could through channel, consistent with low predicted rate. Future observations Square Kilometre Array detect rare sub-class provide strong constraints properties progenitors.