The annular gap model under a rotating dipole field approximation: simulating gamma-ray light curve

TL;DR

This paper enhances the annular gap model for pulsar magnetospheres by incorporating a rotating dipole field, successfully reproducing gamma-ray light curves of three young pulsars and offering a better framework for high-energy emission analysis.

Contribution

It introduces a rotating dipole field into the annular gap model, improving the realism of pulsar magnetosphere simulations and matching observed gamma-ray light curves.

Findings

Open field-line region is enlarged and asymmetric with respect to the fiducial plane.

The model successfully reproduces gamma-ray light curves of three young pulsars.

Provides a new framework for interpreting pulsar high-energy emissions.

Abstract

A more realistic description of the magnetosphere is crucial for understanding the radiation emitted by pulsars. In this paper, we revisit the annular gap model by employing a rotating dipole field, which is more realistic than the static dipole field, as an approximation of the magnetic structure of the pulsar magnetosphere. Compared with the static dipole field approximation, the open field-line region, including both the core and annular gaps, is significantly enlarged, and the two regions become asymmetric with respect to the fiducial plane. We apply this model to three young gamma-ray pulsars with distinct light-curve morphologies, PSRs J0631$+$1036 (single peak), J1709$-$4429 (double peaks), and J1048$-$5832 (three peaks). Using viewing geometries constrained by radio polarization measurements, the annular gap model within the rotating dipole field successfully reproduces the main morphological features of their gamma-ray light curves above 0.1 GeV. Our model provides a framework for interpreting pulsar high-energy emission, which can be used to analyze the emission properties of high-energy pulsars.