Separated before birth: pulsars B2020+28 and B2021+51 as the remnants of runaway stars

TL;DR

This paper proposes a new scenario for the origin of pulsars B2020+28 and B2021+51, suggesting they are remnants of runaway stars ejected from Cyg OB2, challenging previous supernova-based explanations.

Contribution

It introduces a dynamical ejection scenario for pulsar origins, avoiding the need for asymmetric supernova explosions.

Findings

Pulsars may originate from runaway stars ejected by dynamical interactions.

The scenario explains pulsar velocities without asymmetric supernovae.

Astrometric data supports a common origin near Cyg OB2.

Abstract

Astrometric data on the pulsars B2020+28 and B2021+51 suggest that they originated within several parsecs of each other in the direction of the Cyg OB2 association. It was proposed that the pulsars share their origin in a common massive binary and were separated at the birth of the second pulsar following the asymmetric supernova explosion. We consider a different scenario for the origin of the pulsar pair based on a possibility that the pulsars were separated before their birth and that they are the remnants of runaway stars ejected (with velocities similar to those of the pulsars) from the core of Cyg OB2 due to strong three- or four-body dynamical encounters. Our scenario does not require any asymmetry in supernova explosions.