Microscopic Processes in Global Relativistic Jets Containing Helical Magnetic Fields

TL;DR

This paper investigates how helical magnetic fields influence microscopic instabilities in relativistic jets, revealing suppression of some instabilities and emergence of new ones, with implications for jet stability and structure.

Contribution

It presents the first simulations of global relativistic jets with helical magnetic fields, showing their impact on kinetic instabilities and jet dynamics.

Findings

Kinetic instabilities are suppressed by helical magnetic fields.

Recollimation-like instabilities occur in both electron-proton and electron-positron jets.

Larger system simulations are needed for comprehensive understanding.

Abstract

In the study of relativistic jets one of the key open questions is their interaction with the environment on the microscopic level. Here, we study the initial evolution of both electron$-$proton ($e^{-}-p^{+}$) and electron$-$positron ($e^{\pm}$) relativistic jets containing helical magnetic fields, focusing on their interaction with an ambient plasma. We have performed simulations of "global" jets containing helical magnetic fields in order to examine how helical magnetic fields affect kinetic instabilities such as the Weibel instability, the kinetic Kelvin-Helmholtz instability (kKHI) and the Mushroom instability (MI). In our initial simulation study these kinetic instabilities are suppressed and new types of instabilities can grow. In the $e^{-}-p^{+}$ jet simulation a recollimation-like instability occurs and jet electrons are strongly perturbed. In the $e^{\pm}$ jet simulation a recollimation-like instability occurs at early times followed by a kinetic instability and the general structure is similar to a simulation without helical magnetic field. Simulations using much larger systems are required in order to thoroughly follow the evolution of global jets containing helical magnetic fields.