Positron acceleration to ultrarelativistic energies by an oblique magnetosonic shock wave in an electron-positron-ion plasma

Hasegawa, Hirokazu; Ohsawa, Yukiharu

doi:10.1063/1.1827624

Cited by 9 publications

(8 citation statements)

References 40 publications

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“…Positrons and electrons thermalize rapidly during the early stages of shock formation process, while the ions preserve their beam character over tens of ion plasma frequencies and are reflected from the shock front. While in non-relativistic shocks the electrostatic field is responsible for ion reflection [356,322], in relativistic scenarios the electromagnetic fields are more important due to the increased Larmor radius. The upstream ions can penetrate the shock region and enter the downstream, but they will eventually be reflected back into the upstream due to the strong field.…”

Section: Electrostatic Shocksmentioning

confidence: 99%

The microphysics of collisionless shock waves

et al. 2016

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Collisionless shocks, that is shocks mediated by electromagnetic processes, are customary in space physics and in astrophysics. They are to be found in a great variety of objects and environments: magnetospheric and heliospheric shocks, supernova remnants, pulsar winds and their nebulæ, active galactic nuclei, gamma-ray bursts and clusters of galaxies shock waves. Collisionless shock microphysics enters at different stages of shock formation, shock dynamics and particle energization and/or acceleration. It turns out that the shock phenomenon is a multi-scale non-linear problem in time and space. It is complexified by the impact due to high-energy cosmic rays in astrophysical environments. This review adresses the physics of shock formation, shock dynamics and particle acceleration based on a close examination of available multi-wavelength or in situ observations, analytical and numerical developments. A particular emphasis is made on the different instabilities triggered during the shock formation and in association with particle acceleration processes with regards to the properties of the background upstream medium. It appears that among the most important parameters the background magnetic field through the magnetization and its obliquity is the dominant one. The shock velocity that can reach relativistic speeds has also a strong impact over the development of the micro-instabilities and the fate of particle acceleration. Recent developments of laboratory shock experiments has started to bring some new insights in the physics of space plasma and astrophysical shock waves. A special section is dedicated to new laser plasma experiments probing shock physics.

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Section: Electrostatic Shocksmentioning

confidence: 99%

The microphysics of collisionless shock waves

et al. 2016

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“…5) The magnetosonic shock wave with v sh ≃ c cos θ in the strong external magnetic field can also accelerate positrons to ultrarelativistic energies when the plasma consists of ions, electrons, and positrons and the positron density is low. 6,7) In the ultrarelativistic positron acceleration, the electric field parallel to the magnetic field formed in the shock transision region plays an essential role. This result may be applicable to positron acceleration around pulsars because positrons are suspected to exist around the pulsars with the strong magnetic fields, 8,9) and the pulsars have been discussed as one of the sources of cosmic-ray positrons (for example, Refs.…”

Section: And References Therein)mentioning

confidence: 99%

Simulation Study of Trapped Electron Effects on Positron Acceleration by a Shock Wave in an Electron–Ion–Positron Plasma

Toida

2021

J. Phys. Soc. Jpn.

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Positron acceleration by a shock wave in an electro-ion-positron plasma is studied with a two-dimensional, relativistic, electromagnetic particle simulation, with special attention to effects of electrons trapped in the shock wave. It is demonstrated that ultrarelativistic positron acceleration can occur even when the fluctuations along the shock front, which we call 2D fluctuations, excited by the trapped electrons grow to large amplitudes. Further, by comparing the results of the simulation and the calculation of test positrons not influenced by the 2D fluctuations, we show that the positrons influenced by the 2D fluctuations are accelerated to higher energies than the positrons not influenced by them. In addition to the parallel electric field formed in the shock transition region, the perpendicular electric field in the shock wave greatly contributes to the ultrarelativistic positron acceleration under the influence of the 2D fluctuations. Effects of the accelerated positrons on the 2D fluctuations are also discussed.

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“…1 indicates that the quantity F has large positive values. This suggests that another particle beam can be accelerated along B 0 as in the positron acceleration by a magnetosonic shock wave [9].…”

Section: Electromagnetic Fields Driven By An Ion Beammentioning

confidence: 99%

“…For instance, from particle simulations, it was found that magnetosonic shock waves accelerate hydrogen ions [5], heavy ions [6], electrons [7], fast ions [8], and positrons [9] to high energy.…”

Section: Introductionmentioning

confidence: 99%

Particle acceleration by a large-amplitude wave associated with an ion beam in a magnetized plasma

2006

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Abstract. Large-amplitude waves associated with a relativistic ion beam in a magnetized plasma are investigated by means of relativistic electromagnetic particle simulations. In the simulations, it is shown that electromagnetic fields are induced by an ion bunch which has Gaussian density distribution and that their profiles are similar to those of magnetosonic solitons. Further, when an ion beam propagates obliquely to the external magnetic field, it is found that an induced electric field has a parallel component along the magnetic field. Then, as the next step, giving another positron bunch, it is observed that some particles in a positron bunch are accelerated by the parallel electric field.

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Positron acceleration to ultrarelativistic energies by an oblique magnetosonic shock wave in an electron-positron-ion plasma

Cited by 9 publications

References 40 publications

The microphysics of collisionless shock waves

The microphysics of collisionless shock waves

Simulation Study of Trapped Electron Effects on Positron Acceleration by a Shock Wave in an Electron–Ion–Positron Plasma

Particle acceleration by a large-amplitude wave associated with an ion beam in a magnetized plasma

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