Document Type

Article

Publication Date

2-6-2019

Publication Title

Astrophysical Journal

Publisher

The American Astronomical Society

Volume

872

Issue

1

First page number:

1

Last page number:

10

Abstract

As shown by broad-band observations, pulsar wind nebulae (PWNe) are characterized by a broken power-law spectrum of synchrotron emission. Based on the modern magnetohydrodynamic (MHD) turbulence theories, we investigate the re-acceleration of electrons in the PWN through the adiabatic stochastic acceleration (ASA), which arises from fundamental dynamics of MHD turbulence. The ASA acts to flatten the injected energy spectrum of electrons at low energies, while synchrotron cooling results in a steep spectrum of electrons at high energies. Their dominance in different energy ranges leads to a flat radio spectrum (Fν ) and a steep X-ray spectrum. Our analytical spectral shapes generally agree well with the observed synchrotron spectra of radioand X-ray-bright PWNe. The spectral break corresponding to the balance between the ASA and synchrotron losses provides a constraint on the acceleration timescale of the ASA and the magnetic field strength in the PWN.

Keywords

Acceleration of particles; Pulsars:general; Radiation mechanisms: non-thermal; Turbulence

Disciplines

Astrophysics and Astronomy

File Format

PDF

File Size

640 KB

Language

English

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