Wiersma, J. and Achterberg, A. (2005) Magnetic field generation in relativistic shocks. Il nuovo cimento C, 28 (3). pp. 459-462. ISSN 1826-9885
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Abstract
Linear theory of the Weibel instability cannot explain magnetic field generation in relativistic shock fronts in electron-proton plasmas. The fireball model for Gamma-ray Burst afterglows requires a magnetic field in similar shock fronts between the fireball and the surrounding matter to explain the detected nonthermal afterglow radiation. We consider an analytical model of pre-shock protons penetrating the hot post-shock electron plasma. The linear Weibel instability produces magnetic fields through self-enhancing current channels. Perturbations with a length-scale comparable to the electron skin depth reach the highest magnetic field before the linear theory breaks down. The electrons quench the linear proton instability so that it cannot randomize the proton velocity distribution and only converts a small fraction of the available kinetic energy of the protons into magnetic fields. We conclude that the linear Weibel instability that dominates in pair plasmas is relatively unimportant in electron-proton plasmas and that non-linear processes are probably much more important.
| Item Type: | Article |
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| Additional Information: | Paper presented at the “4th Workshop on Gamma-Ray Burst in the Afterglow Era”, Rome, October 18-22, 2004. |
| Uncontrolled Keywords: | Relativistic plasmas ; Micro-instabilities ; Shock waves and discontinuities ; γ-ray sources; γ-ray bursts |
| Subjects: | 500 Scienze naturali e Matematica > 530 Fisica |
| Depositing User: | Marina Spanti |
| Date Deposited: | 16 Mar 2020 11:02 |
| Last Modified: | 16 Mar 2020 11:02 |
| URI: | http://eprints.bice.rm.cnr.it/id/eprint/15695 |
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