The Apparent Asymmetric Outflows of TeV Particles from Pulsar Winds

TL;DR

This paper models the asymmetric TeV particle outflows from pulsar winds, explaining observed filament features through particle transport simulations, and predicts a diffuse X-ray background aligned with these filaments.

Contribution

It introduces a Monte Carlo simulation model for TeV electron/positron transport in pulsar bow shocks, explaining filament asymmetry and predicting associated diffuse X-ray emission.

Findings

TeV e$^{ m iny ext{±}}$ can explain filament properties with modest injection power.

The model predicts a detectable diffuse X-ray background aligned with filaments.

Particle scattering mean free path is comparable to filament length.

Abstract

Observations of X-ray filaments attached to a couple of powerful pulsars suggest escape of TeV electrons and/or positrons (e$^{\pm}$) from pulsar bow shocks into surrounding large scale magnetic fields. These filaments are usually asymmetric with very weak emission from the other side of the main filaments, and no significant spectral variation has been detected across these filaments, implying inefficient energy loss of emitting particles. We develop a Monte Carlo code to simulate particle transport in a large scale magnetic field and apply the model to PSR B2224+4415 (Guitar). It is shown that, with an injection power of a few tens of percent of the pulsar spin down luminosity, TeV e$^{\pm}$ can explain the observed filament properties with a scattering mean free path along the magnetic field comparable to the length of the observed filament. The model predicts a dim diffuse symmetric X-ray background aligned with the filament on a larger scale, whose flux is proportional to the X-ray emitting e$^{\pm}$ energy loss time for a stable e$^{\pm}$ injection power comparable to the luminosity of this diffuse background. Observations with a large field of view and good sensitivity should be able to detect such a component.