Statistics of interpulse radio pulsars - the key to solving the alignment/counter-alignment problem

TL;DR

This paper proposes that the statistical analysis of interpulse radio pulsars can resolve the debate on whether pulsar inclination angles evolve towards alignment or counter-alignment, by examining how their numbers depend on inclination evolution.

Contribution

It introduces a novel method using interpulse pulsar statistics to determine the evolution of pulsar inclination angles, addressing a long-standing ambiguity in pulsar evolution models.

Findings

Interpulse pulsar counts vary significantly with inclination angle evolution.

Statistics can distinguish between alignment and counter-alignment models.

The approach provides a new observational constraint on pulsar braking mechanisms.

Abstract

At present, there are theoretical models of radio pulsar evolution which predict both the alignment, i.e., evolution of inclination angle $\chi$ between magnetic and rotational axes to $0^{\circ}$, and its counter-alignment, i.e., evolution to $90^{\circ}$. At the same time, both models well describe the pulsar distribution on $P$-$\dot P$ diagram. For this reason, up to now it was impossible to determine the braking mechanisms since it was rather difficult to estimate inclination angle evolution on the basis of observation. In this paper we demonstrate that statistics of interpulse pulsars can give us the key to solve alignment/counter-alignment problem as the number of interpulse pulsars (both, having $\chi \sim 0^{\circ}$ and $\chi \sim 90^{\circ}$) drastically depends on evolution of inclination angle.