A magnetospheric dichotomy for pulsars with extreme inclinations

TL;DR

This paper proposes that extreme inclination pulsars exhibit a magnetospheric dichotomy linked to their position relative to death lines, explaining intermittency and nulling through transitions to electrosphere states caused by pair production deficiencies.

Contribution

It introduces a magnetospheric dichotomy model for pulsars with extreme inclinations, connecting their behavior to transitions between active and electrosphere states based on polar potential.

Findings

Intermittent pulsars cluster near specific stripes in period-derivative space.

High-fraction nulling pulsars reside within these stripes, matching death lines.

Magnetospheric transitions explain pulsar intermittency and nulling phenomena.

Abstract

Expanding on the comment by Lyne et al (2017), that intermittent pulsars tend to congregate near a stripe in the logarithmic period versus period-derivative diagram, representing a small range of polar cap electric potential, as well as the fact (already apparent in their Fig.~7, but not explicitly stated there) that high-fraction nulling pulsars also tend to reside within this and an additional stripe, we make the observation that the two stripes further match the "death lines" for double and single-pole interpulses, associated with nearly orthogonal and aligned rotators respectively. These extreme inclinations are known to suffer from pair production deficiencies, so we propose to explain intermittency and high-fraction nulling by reinvigorating some older quiescent (no pulsar wind or radio emission) "electrosphere" solutions. Specifically, as the polar potential drops below the two threshold bands (i.e., the two stripes), corresponding to the aligned and orthogonal rotators, their respective magnetospheres transition from being of the active pair-production-sustained type into becoming the electrospheres, in which charges are only lifted from the star. The borderline cases sitting in the gap outside of the stable regime of either case manifest as high-fraction nullers. Hall evolution of the magnetic field inside orthogonally rotating neutron stars can furthermore drive secular regime changes, resulting in intermittent pulsars.