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arXiv · 1511.03581

Evolution of Global Relativistic Jets: Collimations and Expansion with kKHI and the Weibel Instability

K. I Nishikawa·J. T. Frederiksen·A. Nordlund·Y. Mizuno·P. E. Hardee·J. Niemiec·J. L. Gomez·A. Pe'er·I. Dutan·A. Meli·H. Sol·M. Pohl·D. H. Hartman
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Abstract

One of the key open questions in the study of relativistic jets is their interaction with the environment. Here, we study the initial evolution of both electron-proton and electron-positron relativistic jets, focusing on their lateral interaction with the ambient plasma. We trace the generation and evolution of the toroidal magnetic field generated by both kinetic Kelvin-Helmholtz (kKH) and Mushroom instabilities (MI). This magnetic field collimates the jet. We show that in electron-proton jet, electrons are perpendicularly accelerated with jet collimation. The magnetic polarity switches from the clockwise to anti-clockwise in the middle of jet, as the instabilities weaken. For the electron-positron jet, we find strong mixture of electron-positron with the ambient plasma, that results in the creation of a bow shock. Merger of magnetic field current filaments generate density bumps which initiate a forward shock. The strong mixing between jet and ambient particles prevents full development of the jet on the studied scale. Our results therefore provide a direct evidence for both jet collimation and particle acceleration in the created bow shock. Differences in the magnetic field structures generated by electron-proton and electron-positron jets may contribute to observable differences in the polarized properties of emission by electrons.

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K. I Nishikawa, J. T. Frederiksen, A. Nordlund, Y. Mizuno, P. E. Hardee, J. Niemiec, J. L. Gomez, A. Pe'er, I. Dutan, A. Meli, H. Sol, M. Pohl, D. H. Hartman. 2016-02-04. Evolution of Global Relativistic Jets: Collimations and Expansion with kKHI and the Weibel Instability. https://doi.org/10.3847/0004-637x%2F820%2F2%2F94

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