A Plasma Instability Theory of Gamma‐Ray Burst Emission

Brainerd, J. J.

doi:10.1086/309136

Cited by 45 publications

(42 citation statements)

References 28 publications

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“…In general, these independent simulations have confirmed that relativistic jets excite the Weibel instability (Weibel 1959). The Weibel instability generates current filaments and associated magnetic fields (Medvedev & Loeb 1999;Brainerd 2000;Pruet et al 2001;Gruzinov 2001;Rossi & Rees 2003) and accelerates electrons (Silva et al 2003;Frederiksen et al 2003Frederiksen et al , 2004Paper I).…”

Section: Introductionmentioning

confidence: 65%

“…This work has also provided the time evolution of the distribution functions of beam particles and the generated plasma wave turbulence power spectra. While in these simulations the jet front showed some evidence of Fermi acceleration, the main acceleration of electrons appeared to take place in the downstream region (e.g., Brainerd 2000;Schlickeiser et al 2002;Ostrowski & Bednarz 2002). Further work in this area is required if significant progress is to be made in unraveling the important collisionless processes in relativistic shocks.…”

Section: Introductionmentioning

confidence: 90%

“…Previous microphysical analyses of the energy conversion in relativistic pair outflows interacting with an interstellar medium consisting of cold protons and electrons (e.g., Brainerd 2000;Schlickeiser et al 2002) have demonstrated that the beam excites both electrostatic and low-frequency magnetohydrodynamic Alfvén-type waves via a two-stream instability in the background plasma. This work has also provided the time evolution of the distribution functions of beam particles and the generated plasma wave turbulence power spectra.…”

Section: Introductionmentioning

confidence: 99%

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Particle Acceleration and Magnetic Field Generation in Electron‐Positron Relativistic Shocks

Nishikawa¹,

Hardee²,

Richardson³

et al. 2005

ApJ

141

138

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Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., Buneman, Weibel, and other two-stream instabilities) created in collisionless shocks are responsible for particle (electron, positron, and ion) acceleration. Using a three-dimensional relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic electron-positron jet front propagating into an ambient electron-positron plasma with and without initial magnetic fields. We find small differences in the results for no ambient and modest ambient magnetic fields. New simulations show that the Weibel instability created in the collisionless shock front accelerates jet and ambient particles both perpendicular and parallel to the jet propagation direction. Furthermore, the nonlinear fluctuation amplitudes of densities, currents, and electric and magnetic fields in the electron-positron shock are larger than those found in the electron-ion shock studied in a previous paper at a comparable simulation time. This comes from the fact that both electrons and positrons contribute to generation of the Weibel instability. In addition, we have performed simulations with different electron skin depths. We find that growth times scale inversely with the plasma frequency, and the sizes of structures created by the Weibel instability scale proportionally to the electron skin depth. This is the expected result and indicates that the simulations have sufficient grid resolution. While some Fermi acceleration may occur at the jet front, the majority of electron and positron acceleration takes place behind the jet front and cannot be characterized as Fermi acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying nonuniform, small-scale magnetic fields, which contribute to the electron's (positron's) transverse deflection behind the jet head. This smallscale magnetic field structure is appropriate to the generation of ''jitter'' radiation from deflected electrons (positrons) as opposed to synchrotron radiation. The jitter radiation has different properties than synchrotron radiation calculated assuming a uniform magnetic field. The jitter radiation resulting from small-scale magnetic field structures may be important for understanding the complex time structure and spectral evolution observed in gamma-ray bursts or other astrophysical sources containing relativistic jets and relativistic collisionless shocks.

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Section: Introductionmentioning

confidence: 65%

Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Particle Acceleration and Magnetic Field Generation in Electron‐Positron Relativistic Shocks

Nishikawa¹,

Hardee²,

Richardson³

et al. 2005

ApJ

141

138

View full text Add to dashboard Cite

show abstract

“…The case of heavier ions is ignored, because GRBs seem to exist preferentially in low-metallicity galaxies (see Stanek et al 2006). Two sets of parameters have been given by Brainerd (2000) for the electron density and the ambient magnetic field: case I: n e ¼ 1 cm À3 , B ¼ 0:14 G; case II: n e ¼ 10 5 cm À3 , B ¼ 45 G. We consider each case, labeling the relevant figures case I or case II as appropriate. For case I one then has !…”

Section: Illustrative Examplesmentioning

confidence: 99%

“…The filamentation instability leads to a collapse of the medium into filaments containing strong magnetic fields and high electron temperatures ( Brainerd 2000). Our work allows for the presence of a homogeneous background magnetic field prior to the development of any instability.…”

Section: Introductionmentioning

confidence: 99%

Plasma Instabilities in Gamma‐Ray Bursts: Neutral Points and the Effect of Mode Coupling

Tautz

Lerche

2006

ApJ

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The method of determining neutral points, corresponding to vanishing frequency in wavenumber space, is applied to the case of gamma-ray bursts (GRBs) to determine low-frequency instabilities. If a particular particle distribution function permits the existence of neutral points, instability is guaranteed on one side or the other of the neutral point. By using the rest frame of the GRB jets, only perpendicular particle motion has to be taken into account. The discussion is limited to the cases of a monoenergetic electron-proton plasma with stationary protons and also to a symmetric electronpositron plasma. In the limiting case of wave propagation perpendicular to a homogeneous background magnetic field, taken to be parallel to the streaming direction of the jet, it is shown that to lowest order in the wave frequency, unstable aperiodic fluctuations occur that grow very rapidly on timescales comparable to or smaller than the characteristic times of the GRB, leading to the conclusion that the jets most likely consist mainly of electron-proton plasmas for the cases investigated. Furthermore, high electron Lorentz factors, as well as the coupling effect between longitudinal and transverse modes, are shown to stabilize the system.

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Observational Properties of Cosmic γ-Ray Bursts

Hurley

2003

Supernovae and Gamma-Ray Bursters

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A Plasma Instability Theory of Gamma‐Ray Burst Emission

Cited by 45 publications

References 28 publications

Particle Acceleration and Magnetic Field Generation in Electron‐Positron Relativistic Shocks

Particle Acceleration and Magnetic Field Generation in Electron‐Positron Relativistic Shocks

Plasma Instabilities in Gamma‐Ray Bursts: Neutral Points and the Effect of Mode Coupling

Observational Properties of Cosmic γ-Ray Bursts

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