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Title: The effect of drift on the evolution of the electron/positron spectra in an axisymmetric pulsar wind nebula

Charged particles propagating through a structured magnetic field are subject to drift motion. The primary aim of the present paper is therefore to investigate the effects of gradient, curvature, and neutral sheet drift on the evolution of the electron and positron spectra in a pulsar wind nebula, where the drift motion is a direct result of the magnetic field having an Archimedean spiral structure. In order to investigate the evolution of the spectra, the steady-state, axisymmetric Fokker-Planck transport equation is solved numerically using a finite-difference scheme. Apart from drift motion, the transport processes of convection and diffusion, along with the energy loss processes of adiabatic cooling and synchrotron radiation, are also included in the model. It is found that drift, particularly neutral sheet drift, can lead to a quantitative difference in the evolution of the electron and positron spectra. This difference may be of importance when interpreting the positron excess observed by PAMELA and AMS-02 near Earth.
Authors:
;  [1]
  1. Centre for Space Research, School for Physical and Chemical Sciences, North-West University, 2520 Potchefstroom (South Africa)
Publication Date:
OSTI Identifier:
22356604
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 788; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AXIAL SYMMETRY; CHARGED PARTICLES; DIFFUSION; ELECTRONS; ENERGY LOSSES; FOKKER-PLANCK EQUATION; MAGNETIC FIELDS; NEBULAE; PULSARS; SPECTRA; STEADY-STATE CONDITIONS; STELLAR WINDS; SUPERNOVA REMNANTS; SYNCHROTRON RADIATION; TRANSPORT THEORY