Title

On The Synchrotron Spectrum Of Grb Prompt Emission

Document Type

Article

Publication Date

1-1-2018

Publication Title

Astrophysical Journal

Publisher

Institute of Physics Publishing

Volume

853

Issue

1

Abstract

The prompt emission spectrum of gamma-ray bursts is characterized by a smoothly joint broken power-law spectrum known as the Band function. The typical low-energy photon index is ∼-1, which poses a challenge to standard synchrotron radiation models. We investigate the electron energy spectrum as a result of the interplay among adiabatic stochastic acceleration (ASA), particle injection, and synchrotron cooling. In the ASA-dominated low-energy range, ASA enables an efficient hardening of the injected energy spectrum to approach a spectral index -1. In the synchrotron cooling-dominated high-energy range, the injected high-energy electrons undergo fast synchrotron cooling and have a softer photon spectrum. With the energy range of the injected electrons broadly covering both the ASA- and synchrotron cooling-dominated ranges, the resulting photon number spectrum has low- and high-energy indices of αs ∼ -1 and βs ∼-p 2 -1, respectively. The break energy is of the order of ∼100 keV, depending on the turbulence properties.

Keywords

acceleration of particles; gamma-ray burst: general; radiation mechanisms: non-thermal; turbulence

Language

English

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