Implementation of an offset-dipole magnetic field in a pulsar modelling code

TL;DR

This paper introduces an offset-dipole magnetic field model in pulsar simulations, analyzing its impact on gamma-ray light curves and comparing results with Fermi data for the Vela pulsar.

Contribution

It implements an offset-dipole magnetic field in a pulsar modeling code, expanding the understanding of pulsar magnetospheric geometries and their observational signatures.

Findings

Offset dipole significantly affects light curve shapes.

Model matches observed Vela pulsar data.

Provides a new tool for pulsar emission studies.

Abstract

The light curves of gamma-ray pulsars detected by the Fermi Large Area Telescope show great variety in profile shape and position relative to their radio profiles. Such diversity hints at distinct underlying magnetospheric and/or emission geometries for the individual pulsars. We implemented an offset-dipole magnetic field in an existing geometric pulsar modelling code which already includes static and retarded vacuum dipole fields. In our model, this offset is characterised by a parameter epsilon (with epsilon = 0 corresponding to the static dipole case). We constructed sky maps and light curves for several pulsar parameters and magnetic fields, studying the effect of an offset dipole on the resulting light curves. A standard two-pole caustic emission geometry was used. As an application, we compared our model light curves with Fermi data for the bright Vela pulsar.