Observations of Particle Acceleration in the Blast Waves of Gamma-Ray Bursts

The electron energy distribution index, p, is a fundamental parameter of the process by which electrons at shock fronts are accelerated to relativistic speeds and by which they radiate, via synchrotron emission. This acceleration process is applicable to a myriad of astronomical jet sources such as...

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Main Author: Curran, Peter
Other Authors: J.M. Paredes
Format: Conference Paper
Published: World Scientific Publishing Company 2012
Subjects:
Online Access:http://hdl.handle.net/20.500.11937/33674
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author Curran, Peter
author2 J.M. Paredes
author_facet J.M. Paredes
Curran, Peter
author_sort Curran, Peter
building Curtin Institutional Repository
collection Online Access
description The electron energy distribution index, p, is a fundamental parameter of the process by which electrons at shock fronts are accelerated to relativistic speeds and by which they radiate, via synchrotron emission. This acceleration process is applicable to a myriad of astronomical jet sources such as AGN, X-ray binaries and gamma-ray bursts (GRBs), as well as to particle acceleration in the solar wind and supernovae, and the acceleration of cosmic rays. The accurate measurement of the distribution of p is of fundamental importance to differentiate between the possible theories of electron acceleration at any relativistic shock front; there is division as to whether p has a universal value or whether it has a distribution, and if so, what that distribution is.Here one such source of synchrotron emission is examined: the blast waves of GRB afterglows observed by the Swift satellite. Within the framework of the GRB blast wave model, the constraints placed on the distribution of p by the observed X-ray spectral and temporal indices are examined and the distribution parametrized. The results show that the observed distribution of spectral indices is inconsistent with an underlying distribution of p composed of a single discrete value but consistent with a Gaussian distribution centred at p = 2.4 and having a width of 0.6. This finding disagrees with theoretical work that argues for a single, universal value of p, but also demonstrates that the width of the distribution is not as wide as has been suggested by some authors.
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spelling curtin-20.500.11937-336742023-02-07T08:01:19Z Observations of Particle Acceleration in the Blast Waves of Gamma-Ray Bursts Curran, Peter J.M. Paredes M. Ribó F.A. Aharonian G.E. Romero Shock waves Radiation mechanisms: non-thermal Methods: statistical Gamma-ray burst: general Acceleration - of particles The electron energy distribution index, p, is a fundamental parameter of the process by which electrons at shock fronts are accelerated to relativistic speeds and by which they radiate, via synchrotron emission. This acceleration process is applicable to a myriad of astronomical jet sources such as AGN, X-ray binaries and gamma-ray bursts (GRBs), as well as to particle acceleration in the solar wind and supernovae, and the acceleration of cosmic rays. The accurate measurement of the distribution of p is of fundamental importance to differentiate between the possible theories of electron acceleration at any relativistic shock front; there is division as to whether p has a universal value or whether it has a distribution, and if so, what that distribution is.Here one such source of synchrotron emission is examined: the blast waves of GRB afterglows observed by the Swift satellite. Within the framework of the GRB blast wave model, the constraints placed on the distribution of p by the observed X-ray spectral and temporal indices are examined and the distribution parametrized. The results show that the observed distribution of spectral indices is inconsistent with an underlying distribution of p composed of a single discrete value but consistent with a Gaussian distribution centred at p = 2.4 and having a width of 0.6. This finding disagrees with theoretical work that argues for a single, universal value of p, but also demonstrates that the width of the distribution is not as wide as has been suggested by some authors. 2012 Conference Paper http://hdl.handle.net/20.500.11937/33674 10.1142/S2010194512004655 World Scientific Publishing Company fulltext
spellingShingle Shock waves
Radiation mechanisms: non-thermal
Methods: statistical
Gamma-ray burst: general
Acceleration - of particles
Curran, Peter
Observations of Particle Acceleration in the Blast Waves of Gamma-Ray Bursts
title Observations of Particle Acceleration in the Blast Waves of Gamma-Ray Bursts
title_full Observations of Particle Acceleration in the Blast Waves of Gamma-Ray Bursts
title_fullStr Observations of Particle Acceleration in the Blast Waves of Gamma-Ray Bursts
title_full_unstemmed Observations of Particle Acceleration in the Blast Waves of Gamma-Ray Bursts
title_short Observations of Particle Acceleration in the Blast Waves of Gamma-Ray Bursts
title_sort observations of particle acceleration in the blast waves of gamma-ray bursts
topic Shock waves
Radiation mechanisms: non-thermal
Methods: statistical
Gamma-ray burst: general
Acceleration - of particles
url http://hdl.handle.net/20.500.11937/33674