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

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.