A Physical Model of Pulsar X-ray Filaments

TL;DR

This paper introduces a new physical model for pulsar X-ray filaments driven by cosmic ray-enhanced turbulence, successfully reproducing observed images and spectra without requiring highly amplified magnetic fields, and suggests significant particle escape.

Contribution

The model explains pulsar filament structures using turbulence-driven particle motion, differing from previous models that relied on amplified magnetic fields, and predicts substantial positron escape from filaments.

Findings

Simulated images and spectra match observations of three filaments.

Filament structure depends on interstellar medium properties.

A significant fraction of electrons and positrons escape, affecting local cosmic ray spectra.

Abstract

We present a model for pulsar filaments - a class of narrow X-ray nebulae misaligned with the proper motion, powered by pulsar-generated $e^\pm$. We suggest that cosmic ray-enhanced turbulence drives pitch-angle scattering and dominates $e^\pm$ motion along the filament; highly amplified magnetic fields are not required. A simulation built on this picture, using analytic approximations for the turbulence growth and cosmic ray evolution, generates images and spectra matching observations of the three best-measured filaments. The model structure depends on interstellar medium properties, and fits to filament data require values similar to observed ISM values. In this model a substantial fraction of the filament $e^\pm$ escape, free-streaming for many pc, in contrast to the suppressed cosmic ray diffusion near pulsar TeV halos. Accordingly, nearby low-power filament-generating pulsars may make out-sized contributions to the local positron spectrum. Future X-ray observatories can make the sensitive spectral maps required to test this particle escape.