Linear stability analysis of magnetized relativistic jets: the nonrotating case

TL;DR

This paper conducts a linear stability analysis of non-rotating, magnetized relativistic jets, identifying Kelvin-Helmholtz and current-driven instabilities and their dependence on magnetization and pitch.

Contribution

It provides a detailed analysis of the stability modes in relativistic jets, highlighting the behavior of current-driven modes in relation to magnetization and pitch parameters.

Findings

Kelvin-Helmholtz instability occurs at low magnetizations with weak dependence on pitch.

Current-driven instability dominates at high magnetizations, with growth rates increasing as pitch decreases.

In the relativistic regime, current-driven modes split into two branches with distinct eigenfunction localizations.

Abstract

We perform a linear analysis of the stability of a magnetized relativistic non-rotating cylindrical flow in the aproximation of zero thermal pressure, considering only the m = 1 mode. We find that there are two modes of instability: Kelvin-Helmholtz and current driven. The Kelvin-Helmholtz mode is found at low magnetizations and its growth rate depends very weakly on the pitch parameter. The current driven modes are found at high magnetizations and the value of the growth rate and the wavenumber of the maximum increase as we decrease the pitch parameter. In the relativistic regime the current driven mode is splitted in two branches, the branch at high wavenumbers is characterized by the eigenfunction concentrated in the jet core, the branch at low wavenumbers is instead characterized by the eigenfunction that extends outside the jet velocity shear region.