Magnetic field generation and particle energization at relativistic shear boundaries in collisionless electron-positron plasmas

Abstract

Using particle-in-cell simulations, we study the kinetic physics of relativistic shear flow in collisionless electron–positron (e+e−) plasmas. We find efficient magnetic field generation and particle energization at the shear boundary, driven by streaming instabilities across the shear interface and sustained by the shear flow. Nonthermal, anisotropic high-energy particles are accelerated across field lines to produce a power-law tail turning over just below the shear Lorentz factor. These results have important implications for the dissipation and radiation of jets in blazars and gamma-ray bursts.