Numerical Investigation of Instabilities in Over-pressured Magnetized Relativistic Jets

Fuente: arXiv
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Main Authors: Hu, Xu-Fan, Mizuno, Yosuke, Fromm, Christian M.
Format: Preprint
Published: 2024
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_version_ 1866912188199862272
author Hu, Xu-Fan
Mizuno, Yosuke
Fromm, Christian M.
author_facet Hu, Xu-Fan
Mizuno, Yosuke
Fromm, Christian M.
contents Context. Relativistic jets from Active Galactic Nuclei are observed to be collimated on the parsec scale. When the pressure between the jet and the ambient medium is mismatched, recollimation shocks and rarefaction shocks are formed. Previous numerical simulations have shown that instabilities can destroy the recollimation structure of jets. Aims. In this study, we aim to study the instabilities of non-equilibrium over-pressured relativistic jets with helical magnetic fields. Especially, we investigate how the magnetic pitch affects the development of instabilities. Methods. We perform three-dimensional relativistic magnetohydrodynamic simulations for different magnetic pitches, as well as a two-dimension simulation and a relativistic hydrodynamic simulation served as comparison groups Results. In our simulations, Rayleigh-Taylor Instability (RTI) is triggered at the interface between the jet and ambient medium in the recollimation structure of the jet. We found that when the magnetic pitch decreases the growth of RTI becomes weak but interestingly, another instability, the CD kink instability is excited. The excitement of CD kink instability after passing the recollimation shocks can match the explanation of the quasi-periodic oscillations observed in BL Lac qualitatively.
format Preprint
id arxiv_https___arxiv_org_abs_2411_17389
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Numerical Investigation of Instabilities in Over-pressured Magnetized Relativistic Jets
Hu, Xu-Fan
Mizuno, Yosuke
Fromm, Christian M.
High Energy Astrophysical Phenomena
Context. Relativistic jets from Active Galactic Nuclei are observed to be collimated on the parsec scale. When the pressure between the jet and the ambient medium is mismatched, recollimation shocks and rarefaction shocks are formed. Previous numerical simulations have shown that instabilities can destroy the recollimation structure of jets. Aims. In this study, we aim to study the instabilities of non-equilibrium over-pressured relativistic jets with helical magnetic fields. Especially, we investigate how the magnetic pitch affects the development of instabilities. Methods. We perform three-dimensional relativistic magnetohydrodynamic simulations for different magnetic pitches, as well as a two-dimension simulation and a relativistic hydrodynamic simulation served as comparison groups Results. In our simulations, Rayleigh-Taylor Instability (RTI) is triggered at the interface between the jet and ambient medium in the recollimation structure of the jet. We found that when the magnetic pitch decreases the growth of RTI becomes weak but interestingly, another instability, the CD kink instability is excited. The excitement of CD kink instability after passing the recollimation shocks can match the explanation of the quasi-periodic oscillations observed in BL Lac qualitatively.
title Numerical Investigation of Instabilities in Over-pressured Magnetized Relativistic Jets
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2411.17389