Possible Evidence for Relativistic Shocks in Gamma‐Ray Bursts

1997 ◽  
Vol 488 (1) ◽  
pp. 330-337 ◽  
Author(s):  
E. Cohen ◽  
J. I. Katz ◽  
T. Piran ◽  
R. Sari ◽  
R. D. Preece ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Relativistic Shocks

scholarly journals Advection schemes for capturing relativistic shocks with high Lorentz factors

10.4081/710 ◽  
2012 ◽  
Vol 2 (1) ◽  
pp. e1
Author(s):  
Ahmad A. Hujeirat ◽  
Sophie Fehlmann
Keyword(s):  
Total Energy ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Relativistic Plasmas ◽  
Advection Scheme ◽  
Numerical Studies ◽  
Relativistic Shocks ◽  
Advection Schemes ◽  
General Relativistic ◽  
Energy Formulation

Jet-plasmas emanating from the vicinity of relativistic objects and in gamma-ray bursts have been observed to propagate with Lorentz factors laying in the range between one and several hundreds. On the other hand, the numerical studies of such flows have been focused so far mainly on the lowest possible range of Lorentz factors Γ, specifically, on the regime 1 ≤ Γ ≤ 5. Therefore, relativistic flows with high Γ− factors have poorly studied, as most numerical methods are found to encounter severe numerical difficulties or even become numerically unstable for Γ >> 1. In this paper we present an implicit numerical advection scheme for modeling the propagation of relativistic plasmas with shocks, discuss its consistency with respect to both the internal and total energy formulation in general relativity. Using the total energy formulation, the scheme is found to be viable for modeling moving shocks with moderate Lorentz factors, though with relatively small Courant numbers. In the limit of high Lorentz factors, the internal energy formulation in combination with a fine-tuned artificial viscosity is much more robust and efficient. We confirm our conclusions by performing test calculations and compare the results with analytical solutions of the relativistic shock tube problem. The aim of the present modification is to enhance the robustness of the general relativistic implicit radiative MHD solver: GR-I-RMHD (http://www1.iwr.uni-heidelberg.de/groups/compastro/home/gr-i-mhdsolver) and extend its range of applications into the high Γ− regime.

scholarly journals Particle Acceleration in Gamma-Ray Bursts

2005 ◽  
Vol 192 ◽  
pp. 475-482
Author(s):  
J.G. Kirk
Keyword(s):  
Magnetic Field ◽  
Particle Acceleration ◽  
Shock Front ◽  
Gamma Ray ◽  
Crab Nebula ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Magnetic Field Generation ◽  
Relativistic Shocks ◽  
The Crab Nebula

SummarySimple kinematic theories of particle acceleration at relativistic shocks lead to the prediction of a high-energy spectral index of −1.1 for the energy flux of synchrotron photons. However, several effects can change this picture. In this paper I discuss the effect of magnetic field generation at the shock front and, by analogy with the Crab Nebula, suggest that an intrinsic break in the injection spectrum should be expected where the electron gyro radius is comparable to that of protons thermalized by the shock.

scholarly journals COLLISIONLESS RELATIVISTIC SHOCKS: CURRENT DRIVEN TURBULENCE AND PARTICLE ACCELERATION

2014 ◽  
Vol 28 ◽  
pp. 1460193
Author(s):  
GUY PELLETIER ◽  
MARTIN LEMOINE ◽  
LAURENT GREMILLET ◽  
ILLYA PLOTNIKOV
Keyword(s):  
Particle Acceleration ◽  
Gamma Ray ◽  
Mean Field ◽  
Critical Value ◽  
Gamma Ray Bursts ◽  
Incoming Flow ◽  
Buffer Effect ◽  
Relativistic Shocks ◽  
Onset Of Turbulence ◽  
The Mean

The physics of collisionless relativistic shocks with a moderate magnetization is presented. Micro-physics is relevant to explain the most energetic radiative phenomena of Nature, namely that of the termination shock of Gamma Ray Bursts. A transition towards Fermi process occurs for decreasing magnetization around a critical value which turns out to be the condition for the scattering to break the mean field inhibition. Scattering is produced by magnetic micro-turbulence driven by the current carried by returning particles, which had not been considered till now, but turns out to be more intense than Weibel's one around the transition. The current is also responsible for a buffer effect on the motion of the incoming flow, on which the threshold for the onset of turbulence depends.

scholarly journals Advection schemes for capturing relativistic shocks with high Lorentz factors

2012 ◽  
Vol 2 (1) ◽  
pp. e1
Author(s):  
Ahmad A. Hujeirat ◽  
Sophie Fehlmann
Keyword(s):  
Total Energy ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Relativistic Plasmas ◽  
Advection Scheme ◽  
Numerical Studies ◽  
Relativistic Shocks ◽  
Advection Schemes ◽  
General Relativistic ◽  
Energy Formulation

Jet-plasmas emanating from the vicinity of relativistic objects and in gamma-ray bursts have been observed to propagate with Lorentz factors laying in the range between one and several hundreds. On the other hand, the numerical studies of such flows have been focused so far mainly on the lowest possible range of Lorentz factors Γ, specifically, on the regime 1 ≤ Γ ≤ 5. Therefore, relativistic flows with high Γ− factors have poorly studied, as most numerical methods are found to encounter severe numerical difficulties or even become numerically unstable for Γ >> 1. In this paper we present an implicit numerical advection scheme for modeling the propagation of relativistic plasmas with shocks, discuss its consistency with respect to both the internal and total energy formulation in general relativity. Using the total energy formulation, the scheme is found to be viable for modeling moving shocks with moderate Lorentz factors, though with relatively small Courant numbers. In the limit of high Lorentz factors, the internal energy formulation in combination with a fine-tuned artificial viscosity is much more robust and efficient. We confirm our conclusions by performing test calculations and compare the results with analytical solutions of the relativistic shock tube problem. The aim of the present modification is to enhance the robustness of the general relativistic implicit radiative MHD solver: GR-I-RMHD (http://www1.iwr.uni-heidelberg.de/groups/compastro/home/gr-i-mhdsolver) and extend its range of applications into the high Γ− regime.

The Events in Context

2011 ◽  
Author(s):  
Joshua S. Bloom
Keyword(s):  
Gamma Ray ◽  
Cosmic Time ◽  
Crime Scene ◽  
Gamma Ray Bursts ◽  
Forensic Evidence ◽  
Relativistic Shocks ◽  
Central Engine ◽  
Universal Scale

Prompt and afterglow emission of gamma-ray bursts (GRBs) are largely driven by the central engine behavior, the explosion properties, and the physics of relativistic shocks. Those seconds, minutes, and days after the main event tell a remarkable story about how the progenitors of GRBs end their life. But it is the context—where GRBs occur inside and out of galaxies and throughout cosmic time—that tell us how the progenitors lived. Indeed, GRB locations are treated like a crime scene, extracting forensic evidence to make a case about the lifecycle of a GRB progenitor. This chapter discusses local-, galactic-, and universal-scale observations of GRBs.

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