3D PIC Simulations for relativistic jets with a toroidal magnetic field

We have investigated how kinetic instabilities such as the Weibel instability (WI), the mushroom instability (MI), and the kinetic Kelvin–Helmholtz instability (kKHI) are excited in jets without and with a toroidal magnetic field, and how such instabilities contribute to particle acceleration. In this work, we use a new jet injection scheme, where an electric current is self-consistently generated at the jet orifice by the jet particles, which produce the toroidal magnetic field.

We perform five different simulations for a sufficiently long time to examine the non-linear effects of the jet evolution. We inject unmagnetized e± and e−– p+ (mp/me = 1836), as well as magnetized e± and e−– i+ (mi/me = 4) jets with a top-hat jet density profile into an unmagnetized ambient plasmas of the same species.

We show that WI, MI, and kKHI excited at the linear stage, generate a non-oscillatory x-component of the electric field accelerating, and decelerating electrons. We find that the two different jet compositions (e± and e−– i+) display different instability modes, respectively. Moreover, the magnetic field in the non-linear stage generated by different instabilities is dissipated and reorganized into new topologies.

A 3D magnetic field topology depiction indicates possible reconnection sites in the non-linear stage, where the particles are significantly accelerated by the dissipation of the magnetic field associated to a possible reconnection event.