Synthetic Spectra from Particle-in-cell Simulations of Relativistic Jets containing an initial Toroidal Magnetic Field

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Main Authors: Dutan, Ioana, Nishikawa, Kenichi, Meli, Athina, Kobzar, Oleh, Koehn, Christoph, Mizuno, Yosuke, MacDonald, Nicholas, Gomez, Jose L., Hirotani, Kouichi
Format: Preprint
Published: 2024
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author Dutan, Ioana
Nishikawa, Kenichi
Meli, Athina
Kobzar, Oleh
Koehn, Christoph
Mizuno, Yosuke
MacDonald, Nicholas
Gomez, Jose L.
Hirotani, Kouichi
author_facet Dutan, Ioana
Nishikawa, Kenichi
Meli, Athina
Kobzar, Oleh
Koehn, Christoph
Mizuno, Yosuke
MacDonald, Nicholas
Gomez, Jose L.
Hirotani, Kouichi
contents The properties of relativistic jets, their interaction with the environment, and their emission of radiation can be self-consistently studied by using collisionless particle-in-cell (PIC) numerical simulations. Using three-dimensional (3D), relativistic PIC simulations, we present the first self-consistently calculated synthetic spectra of head-on and off-axis emission from electrons accelerated in cylindrical, relativistic plasma jets containing an initial toroidal magnetic field. The jet particles are initially accelerated during the linear stage of growing plasma instabilities, which are the Weibel instability (WI), kinetic Kelvin-Helmholtz instability (kKHI), and mushroom instability (MI). In the nonlinear stage, these instabilities are dissipated and generate turbulent magnetic fields which accelerate particles further. We calculate the synthetic spectra by tracing a large number of jet electrons in the nonlinear stage, near the jet head where the magnetic fields are turbulent. Our results show the basic properties of jitter-like radiation emitted by relativistic electrons when they travel through a magnetized plasma with the plasma waves driven by kinetic instabilities (WI, kKHI, and MI) growing into the nonlinear regime. At low frequencies, the slope of the spectrum is ~ 0.94, which is similar to that of the jitter radiation, rather than that of the classical synchrotron radiation which is ~ 1/3. Although, we start with a weak magnetized plasma, the plasma magnetization increases locally in regions where the magnetic field becomes stronger due to kinetic instabilities. The results of this study may be relevant for probing photon emission from low energies up to, at least, low energies in the X-ray domain in AGN/blazar and GRB jets, as the peak frequency of synthetic spectra increases as the Lorentz factor of the jet increases from 15 to 100.
format Preprint
id arxiv_https___arxiv_org_abs_2404_07392
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Synthetic Spectra from Particle-in-cell Simulations of Relativistic Jets containing an initial Toroidal Magnetic Field
Dutan, Ioana
Nishikawa, Kenichi
Meli, Athina
Kobzar, Oleh
Koehn, Christoph
Mizuno, Yosuke
MacDonald, Nicholas
Gomez, Jose L.
Hirotani, Kouichi
High Energy Astrophysical Phenomena
The properties of relativistic jets, their interaction with the environment, and their emission of radiation can be self-consistently studied by using collisionless particle-in-cell (PIC) numerical simulations. Using three-dimensional (3D), relativistic PIC simulations, we present the first self-consistently calculated synthetic spectra of head-on and off-axis emission from electrons accelerated in cylindrical, relativistic plasma jets containing an initial toroidal magnetic field. The jet particles are initially accelerated during the linear stage of growing plasma instabilities, which are the Weibel instability (WI), kinetic Kelvin-Helmholtz instability (kKHI), and mushroom instability (MI). In the nonlinear stage, these instabilities are dissipated and generate turbulent magnetic fields which accelerate particles further. We calculate the synthetic spectra by tracing a large number of jet electrons in the nonlinear stage, near the jet head where the magnetic fields are turbulent. Our results show the basic properties of jitter-like radiation emitted by relativistic electrons when they travel through a magnetized plasma with the plasma waves driven by kinetic instabilities (WI, kKHI, and MI) growing into the nonlinear regime. At low frequencies, the slope of the spectrum is ~ 0.94, which is similar to that of the jitter radiation, rather than that of the classical synchrotron radiation which is ~ 1/3. Although, we start with a weak magnetized plasma, the plasma magnetization increases locally in regions where the magnetic field becomes stronger due to kinetic instabilities. The results of this study may be relevant for probing photon emission from low energies up to, at least, low energies in the X-ray domain in AGN/blazar and GRB jets, as the peak frequency of synthetic spectra increases as the Lorentz factor of the jet increases from 15 to 100.
title Synthetic Spectra from Particle-in-cell Simulations of Relativistic Jets containing an initial Toroidal Magnetic Field
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2404.07392