Magnetic Field Generation and Particle Energization in Relativistic Shear Flows

This paper summarizes recent results obtained from 2 -and -3 D particle-in-cell (PIC) simulations of relativistic shear boundary layers (SBL). In addition to the creation of sustained, ordered magnetic fields due to counter-current instabilities, we find efficient energization of nonthermal electrons to high energies, making the SBL a strong candidate for enhanced synchrotron emission in relativistic jets, from blazars to gamma-ray bursts. The case of mixed electron-positron-ion shear flows is particularly interesting as it leads to the formation of an electron spectrum with both a high-energy peak near the ion kinetic energy, plus a hard power-law tail of slope near -- 3, which strongly resembles electron distributions responsible for the emissions of GRB and blazars. The electron momentum distribution exhibits extreme anisotropy, making the SBL a strong candidate for narrowly beamed synchrotron-self-Compton (SSC) radiation in some cases.