A Laminar Model for the Magnetic Field Structure in Bow-Shock Pulsar Wind Nebulae

TL;DR

This paper introduces a simplified laminar model to analyze the magnetic field structure in bow-shock pulsar wind nebulae, aiding in understanding their emission patterns and system orientations.

Contribution

It presents a novel laminar modeling approach using Lagrangian tracers to study magnetic fields in bow-shock pulsar wind nebulae, which was previously limited by complex multidimensional analyses.

Findings

Computed magnetic field geometries for various configurations.

Generated radio emission maps including polarization patterns.

Provided insights into constraining system orientation and turbulence presence.

Abstract

Bow Shock Pulsar Wind Nebulae are a class of non-thermal sources, that form when the wind of a pulsar moving at supersonic speed interacts with the ambient medium, either the ISM or in a few cases the cold ejecta of the parent supernova. These systems have attracted attention in recent years, because they allow us to investigate the properties of the pulsar wind in a different environment from that of canonical Pulsar Wind Nebulae in Supernova Remnants. However, due to the complexity of the interaction, a full-fledged multidimensional analysis is still laking. We present here a simplified approach, based on Lagrangian tracers, to model the magnetic field structure in these systems, and use it to compute the magnetic field geometry, for various configurations in terms of relative orientation of the magnetic axis, pulsar speed and observer direction. Based on our solutions we have computed a set of radio emission maps, including polarization, to investigate the variety of possible appearances, and how the observed emission pattern can be used to constrain the orientation of the system, and the possible presence of turbulence.