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

2020 ◽  
Vol 493 (2) ◽  
pp. 2652-2658
Author(s):  
Kenichi Nishikawa ◽  
Yosuke Mizuno ◽  
Jose L Gómez ◽  
Ioana Duţan ◽  
Jacek Niemiec ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Reconnection ◽  
Large Radius ◽  
Linear Stage ◽  
Relativistic Jets ◽  
Particle In Cell ◽  
Helical Magnetic Field ◽  
Kinetic Instabilities ◽  
Key Questions

ABSTRACT One of the key questions in the study of relativistic jets is how magnetic reconnection occurs and whether it can effectively accelerate electrons in the jet. We performed 3D particle-in-cell (PIC) simulations of a relativistic electron–proton jet of relatively large radius that carries a helical magnetic field. We focused our investigation on the interaction between the jet and the ambient plasma and explore how the helical magnetic field affects the excitation of kinetic instabilities such as the Weibel instability (WI), the kinetic Kelvin–Helmholtz instability (kKHI), and the mushroom instability (MI). In our simulations these kinetic instabilities are indeed excited, and particles are accelerated. At the linear stage we observe recollimation shocks near the centre of the jet. As the electron–proton jet evolves into the deep non-linear stage, the helical magnetic field becomes untangled due to reconnection-like phenomena, and electrons are repeatedly accelerated as they encounter magnetic-reconnection events in the turbulent magnetic field.

scholarly journals Particle-in-cell Simulations of Global Relativistic Jets with Helical Magnetic Fields

2016 ◽  
Vol 12 (S324) ◽  
pp. 199-202 ◽  
Author(s):  
Ioana Duţan ◽  
Ken-Ichi Nishikawa ◽  
Yosuke Mizuno ◽  
Jacek Niemiec ◽  
Oleh Kobzar ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
General Structure ◽  
Relativistic Jets ◽  
Particle In Cell ◽  
Electron Positron ◽  
New Findings ◽  
Kinetic Instability ◽  
Composition I ◽  
Helical Magnetic Field ◽  
Kinetic Instabilities

AbstractWe study the interaction of relativistic jets with their environment, using 3-dimen- sional relativistic particle-in-cell simulations for two cases of jet composition: (i) electron-proton (e− − p+) and (ii) electron-positron (e±) plasmas containing helical magnetic fields. 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 and the Mushroom instability. We have found that these kinetic instabilities are suppressed and new types of instabilities can grow. For the e− − p+ jet, a recollimation-like instability occurs and jet electrons are strongly perturbed, whereas for the e± jet, a recollimation-like instability occurs at early times followed by kinetic instability and the general structure is similar to a simulation without a helical magnetic field. We plan to perform further simulations using much larger systems to confirm these new findings.

scholarly journals Microscopic Processes In Global Relativistic Jets Containing Helical Magnetic Fields

2016 ◽  
Author(s):  
Kenichi Nishikawa ◽  
Yosuke Mizuno ◽  
Jacek Niemiec ◽  
Oleh Kobzar ◽  
Martin Pohl ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
General Structure ◽  
Microscopic Level ◽  
Relativistic Jets ◽  
Helmholtz Instability ◽  
Open Questions ◽  
Initial Evolution ◽  
Kinetic Instability ◽  
Helical Magnetic Field ◽  
Kinetic Instabilities

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 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.

scholarly journals PIC methods in astrophysics: simulations of relativistic jets and kinetic physics in astrophysical systems

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Kenichi Nishikawa ◽  
Ioana Duţan ◽  
Christoph Köhn ◽  
Yosuke Mizuno
Keyword(s):  
Plasma Physics ◽  
Magnetic Reconnection ◽  
Laser Plasma ◽  
High Performance ◽  
Relativistic Jets ◽  
Astrophysical Plasmas ◽  
Computing Power ◽  
Particle In Cell ◽  
The Future ◽  
Pic Method

AbstractThe Particle-In-Cell (PIC) method has been developed by Oscar Buneman, Charles Birdsall, Roger W. Hockney, and John Dawson in the 1950s and, with the advances of computing power, has been further developed for several fields such as astrophysical, magnetospheric as well as solar plasmas and recently also for atmospheric and laser-plasma physics. Currently more than 15 semi-public PIC codes are available which we discuss in this review. Its applications have grown extensively with increasing computing power available on high performance computing facilities around the world. These systems allow the study of various topics of astrophysical plasmas, such as magnetic reconnection, pulsars and black hole magnetosphere, non-relativistic and relativistic shocks, relativistic jets, and laser-plasma physics. We review a plethora of astrophysical phenomena such as relativistic jets, instabilities, magnetic reconnection, pulsars, as well as PIC simulations of laser-plasma physics (until 2021) emphasizing the physics involved in the simulations. Finally, we give an outlook of the future simulations of jets associated to neutron stars, black holes and their merging and discuss the future of PIC simulations in the light of petascale and exascale computing.

Hybrid-Vlasov modelling of three-dimensional dayside magnetopause reconnection

2021 ◽  
Author(s):  
Yann Pfau-Kempf ◽  
Minna Palmroth ◽  
Andreas Johlander ◽  
Lucile Turc ◽  
Markku Alho ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Reconnection ◽  
Three Dimensional ◽  
Meridional Plane ◽  
Kinetic Behavior ◽  
Dayside Magnetopause ◽  
Field Junction ◽  
First Time ◽  
Kinetic Instabilities ◽  
Magnetopause Reconnection

<p>Dayside magnetic reconnection at the magnetopause, which is a major driver of space weather, is studied for the first time in a three-dimensional (3D) realistic setup using the Vlasiator hybrid-Vlasov kinetic model. A noon–midnight meridional plane simulation is extended in the dawn–dusk direction to cover 7 Earth radii. The southward interplanetary magnetic field causes magnetic reconnection to occur at the subsolar magnetopause. Perturbations arising from kinetic instabilities in the magnetosheath appear to modulate the reconnection. Its characteristics are consistent with multiple, bursty, and patchy magnetopause reconnection. It is shown that the kinetic behavior of the plasma, as simulated by the model, has consequences on the applicability of methods such as the four-field junction to identify and analyse magnetic reconnection in 3D kinetic simulations.</p>

scholarly journals Concerning the occurrence pattern of flux transfer events on the dayside magnetopause

2009 ◽  
Vol 27 (2) ◽  
pp. 895-903 ◽  
Author(s):  
D. G. Sibeck
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Magnetic Reconnection ◽  
Interplanetary Magnetic Field ◽  
Flux Transfer Events ◽  
Dayside Magnetopause ◽  
Two Factors ◽  
Flux Transfer ◽  
Occurrence Pattern ◽  
The Magnetic Field

Abstract. We present an analytical model for the magnetic field perturbations associated with flux transfer events (FTEs) on the dayside magnetopause as a function of the shear between the magnetosheath and magnetospheric magnetic fields and the ratio of their strengths. We assume that the events are produced by component reconnection along subsolar reconnection lines with tilts that depend upon the orientation of the interplanetary magnetic field (IMF), and show that the amplitudes of the perturbations generated during southward IMF greatly exceed those during northward IMF. As a result, even if the distributions of magnetic reconnection burst durations/event dimensions are identical during periods of northward and southward IMF orientation, events occurring for southward IMF orientations must predominate in surveys of dayside events. Two factors may restore the balance between events occurring for northward and southward IMF orientations on the flanks of the magnetosphere. Events generated on the dayside magnetopause during periods of southward IMF move poleward, while those generated during periods of northward IMF slip dawnward or duskward towards the flanks. Due to differing event and magnetospheric magnetic field orientations, events that produce weak signatures on the dayside magnetopause during intervals of northward IMF orientation may produce strong signatures on the flanks.

scholarly journals PARTICLE ACCELERATION, MAGNETIC FIELD GENERATION, AND ASSOCIATED EMISSION IN COLLISIONLESS RELATIVISTIC JETS

2008 ◽  
Vol 17 (10) ◽  
pp. 1761-1767 ◽  
Author(s):  
K.-I. NISHIKAWA ◽  
Y. MIZUNO ◽  
G. J. FISHMAN ◽  
P. HARDEE
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Small Scale ◽  
Spectral Structure ◽  
Relativistic Jets ◽  
Weibel Instability ◽  
Electron Positron ◽  
Jitter Radiation

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations using injected relativistic electron-ion (electron-positron) jets show that acceleration occurs within the downstream jet. Shock acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electrons' transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties to synchrotron radiation which assumes a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

Numerical investigation of a plasma beam entering transverse magnetic fields

1989 ◽  
Vol 42 (1) ◽  
pp. 91-110 ◽  
Author(s):  
J. Koga ◽  
J. L. Geary ◽  
T. Fujinami ◽  
B. S. Newberger ◽  
T. Tajima ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Transverse Magnetic ◽  
Beam Momentum ◽  
Injection Velocity ◽  
Electron Mass ◽  
Particle In Cell ◽  
Plasma Beam ◽  
Beam Injection ◽  
The Magnetic Field

We study plasma-beam injection into transverse magnetic fields using both electrostatic and electromagnetic particle-in-cell (PIC) codes. In the case of small beam momentum or energy (low drift kinetic β) we study both large- and small-ion-gyroradius beams. Large-ion-gyroradius beams with a large dielectric constant ε ≫ (M/m)½ are found to propagate across the magnetic field via E × B drifts at nearly the initial injection velocity, where and M/m is the ion-to-electron mass ratio. Beam degradation and undulations are observed, in agreement with previous experimental and analytical results. When ε is of order (M/m)½ the plasma beam propagates across field lines at only half its initial velocity and loses its coherent structure. When ε is much less than (M/m)½ the beam particles decouple at the magnetic field boundary, scattering the electrons and slightly deflecting the ions. For small-ion-gyroradius beam injection a flute-type instability is observed at the beam-magnetic-field interface. In the case of large beam momentum or energy (high drift kinetic β) we observe good penetration of a plasma beam by shielding the magnetic field from the interior of the beam (diamagnetism). However, we observe anomalously fast penetration of the magnetic field into the beam and find that the diffusion rate depends on the electron gyroradius of the beam.

scholarly journals Hot gas heating via magnetic arms in spiral galaxies

2020 ◽  
Vol 640 ◽  
pp. A109
Author(s):  
M. Weżgowiec ◽  
M. Ehle ◽  
M. Soida ◽  
R.-J. Dettmar ◽  
R. Beck ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Radio Emission ◽  
Magnetic Reconnection ◽  
Spiral Galaxy ◽  
Surrounding Medium ◽  
Spiral Arms ◽  
X Ray ◽  
Hot Gas ◽  
Gas Heating

Context. Reconnection heating has been considered as a potential source of the heating of the interstellar medium. In some galaxies, significant polarised radio emission has been found between the spiral arms. This emission has a form of “magnetic arms” that resembles the spiral structure of the galaxy. Reconnection effects could convert some of the energy of the turbulent magnetic field into the thermal energy of the surrounding medium, leaving more ordered magnetic fields, as is observed in the magnetic arms. Aims. Sensitive radio and X-ray data for the grand-design spiral galaxy M 83 are used for a detailed analysis of the possible interactions of magnetic fields with hot gas, including a search for signatures of gas heating by magnetic reconnection effects. Methods. Magnetic field strengths and energies derived from the radio emission are compared with the parameters of the hot gas calculated from the model fits to sensitive X-ray spectra of the hot gas emission. Results. The available X-ray data allowed us to distinguish two thermal components in the halo of M 83. We found slightly higher average temperatures of the hot gas in the interarm regions, which results in higher energies per particle and is accompanied by a decrease in the energy density of the magnetic fields. Conclusions. The observed differences in the energy budget between the spiral arms and the interarm regions suggest that, similar to the case of another spiral galaxy NGC 6946, we may be observing hints for gas heating by magnetic reconnection effects in the interarm regions. These effects, which act more efficiently on the turbulent component of the magnetic field, are expected to be stronger in the spiral arms. However, with the present data it is only possible to trace them in the interarm regions, where the star formation and the resulting turbulence is low.

scholarly journals Noise-induced magnetic field saturation in kinetic simulations

2020 ◽  
Vol 86 (4) ◽  
Author(s):  
J. Juno ◽  
M. M. Swisdak ◽  
J. M. Tenbarge ◽  
V. Skoutnev ◽  
A. Hakim
Keyword(s):  
Magnetic Field ◽  
Sampling Error ◽  
Kinetic Equations ◽  
Particle Methods ◽  
Induced Magnetic Field ◽  
Particle Count ◽  
Particle In Cell ◽  
Broad Array ◽  
The Magnetic Field ◽  
Kinetic Instabilities

Monte Carlo methods are often employed to numerically integrate kinetic equations, such as the particle-in-cell method for the plasma kinetic equation, but these methods suffer from the introduction of counting noise to the solution. We report on a cautionary tale of counting noise modifying the nonlinear saturation of kinetic instabilities driven by unstable beams of plasma. We find a saturated magnetic field in under-resolved particle-in-cell simulations due to the sampling error in the current density. The noise-induced magnetic field is anomalous, as the magnetic field damps away in continuum kinetic and increased particle count particle-in-cell simulations. This modification of the saturated state has implications for a broad array of astrophysical phenomena beyond the simple plasma system considered here, and it stresses the care that must be taken when using particle methods for kinetic equations.

scholarly journals HELICAL MAGNETIC FIELDS IN RELATIVISTIC JETS THROUGH FARADAY ROTATION AND JET STRATIFICATION STUDIES

2012 ◽  
Vol 08 ◽  
pp. 265-270
Author(s):  
JOSÉ L. GÓMEZ ◽  
CAROLINA CASADIO ◽  
MAR ROCA-SOGORB ◽  
IVÁN AGUDO ◽  
ALAN P. MARSCHER ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Faraday Rotation ◽  
Galactic Nuclei ◽  
Relativistic Jets ◽  
Long Baseline ◽  
Rotation Measure ◽  
Very Long Baseline Array ◽  
Helical Magnetic Field ◽  
3C 120 ◽  
Emission Stratification

Helical magnetic fields may play an important role in the formation, collimation, and acceleration of relativistic jets in active galactic nuclei. These may be searched for by looking for Faraday rotation measure (RM) gradients and emission stratification across the jet width. Multi-epoch polarimetric Very Long Baseline Array (VLBA) observations of the radio galaxy 3C 120 have revealed the existence of such a RM gradient across the jet, but the presence of a localized region of enhanced RM and uncorrelated changes in the polarization of the underlying jet emission and the Faraday rotation screen suggest that a significant fraction of the RM found in 3C 120 originates in foreground clouds. Thanks to the combination of 48 images spanning 14 years of 15 GHz VLBA observations of 3C 273 we have found a stratification in total intensity across the jet that flips sides with distance along the jet, supporting a model in which the jet of 3C 273 accelerates and is threaded by a helical magnetic field.

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