Early Accretion Onset in Long-Period Isolated Pulsars

TL;DR

This paper models the long-term evolution of isolated neutron stars with long initial spin periods, showing they can start accreting from the interstellar medium within a few billion years, especially if born at certain evolutionary stages.

Contribution

It introduces a model demonstrating that long-period isolated neutron stars can begin accretion earlier than previously thought, especially considering their initial spin and velocity.

Findings

Neutron stars with velocities $ extless 100$ km/s can reach accretion stage within a few billion years.

Long initial spin periods do not prevent neutron stars from becoming accretors.

The number of isolated accretors may be larger than previously predicted.

Abstract

We model long-term magneto-rotational evolution of isolated neutron stars with long initial spin periods. This analysis is motivated by the recent discovery of young long-period neutron stars observed as periodic radio sources: PSR J0901-4046, GLEAM-X J1627-52, and GPM J1839-10. Our calculations demonstrate that for realistically rapid spin-down during the propeller stage isolated neutron stars with velocities $\lesssim100$ km s$^{-1}$ and assumed long initial spin periods can reach the stage of accretion from the interstellar medium within at most a few billion years as they are born already at the propeller stage or sufficiently close to the critical period of the ejector-propeller transition. If neutron stars with long initial spin periods form a relatively large fraction of all Galactic neutron stars then the number of isolated accretors is substantially larger than it has been predicted by previous studies.