Microscopic Processes in Global Relativistic Jets Containing Helical Magnetic Fields

Abstract

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 ± ) 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 ± 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.

Rapid particle acceleration due to recollimation shocks and turbulent magnetic fields in injected jets with helical magnetic fields

“…1b). Note, that the simulation setup adopted in this work has been used in our preliminary studies of helical jets (Nishikawa et al 2016b(Nishikawa et al , 2017(Nishikawa et al , 2019.…”

Exploring the Connection between Parsec-scale Jet Activity and Broadband Outbursts in 3C 279

“…Since the mean polarization is the maximum divided by the square-root of the number of cells 14 involved in the emission, the observed anti-correlation between gamma-ray flux and optical PP could be because of the presence of more turbulent cells during the outburst than at other times. The jet plasma is highly dynamic; plasma instabilities (e.g., the current-driven kink instability and/or magnetohydrodynamical instabilities Nishikawa et al 2016;Nalewajko & Begelman 2012) could occur and vary with time, which basically drives the turbulence. In short, instabilities drive turbulence which can influence the number of cells in a given emission region.…”

Microscopic Processes in Global Relativistic Jets Containing Helical Magnetic Fields: Dependence on Jet Radius

“…In our simulations [5], cylindrical jets are injected with a helical magnetic field implemented like that in RMHD simulations performed by Mizuno et al [10]. Our simulations use Cartesian coordinates.…”

“…The jet and ambient (electron) plasma number density measured in the simulation frame is n jt = 8 and n am = 12, respectively. This set of densities of jet and ambient plasmas is used in our previous simulations [4][5][6] In the simulations, the electron skin depth λ s = c/ω pe = 10.0∆, where c is the speed of light, ω pe = (e 2 n am /ǫ 0 m e ) 1/2 is the electron plasma frequency, and the electron Debye length for the ambient electrons is λ D = 0.5∆. The jet-electron thermal velocity is v jt,th,e = 0.014c in the jet reference frame.…”

“…The simple recollimation shock generated in the small jet radius is shown in Figs. 1(a) and 1(b) [5]. We need to perform longer simulations in order to investigate full development of instabilities and jets with helical magnetic fields.…”