Electron Acceleration by Multi-Island Coalescence

Oka, M.; Phan, T. D.; Krucker, S.; Fujimoto, M.; Shinohara, I.

doi:10.1088/0004-637x/714/1/915

Cited by 253 publications

(286 citation statements)

References 42 publications

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“…An early analytical study of test particle orbits around X-line field topology with and without a guide field (where the electrons remain magnetized) was performed by Bulanov and Sasorov (1976) and later advanced with Particle-in-Cell (PIC) technique (see, e.g., Oka et al 2010, Bessho and Bhattacharjee 2012, Sironi and Spitkovsky 2012. Bulanov and Sasorov (1976) came up with an exponential asymptotic shape of the energetic electron spectra in both relativistic and nonrelativistic regime.…”

Section: Particle Acceleration and Non-thermal Radiation In Starburstmentioning

confidence: 99%

Nonthermal particles and photons in starburst regions and superbubbles

Bykov

2014

Astron Astrophys Rev

111

102

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Starforming factories in galaxies produce compact clusters and loose associations of young massive stars. Fast radiation-driven winds and supernovae input their huge kinetic power into the interstellar medium in the form of highly supersonic and superalfvenic outflows. Apart from gas heating, collisionless relaxation of fast plasma outflows results in fluctuating magnetic fields and energetic particles. The energetic particles comprise a long-lived component which may contain a sizeable fraction of the kinetic energy released by the winds and supernova ejecta and thus modify the magnetohydrodynamic flows in the systems. We present a concise review of observational data and models of nonthermal emission from starburst galaxies, superbubbles, and compact clusters of massive stars. Efficient mechanisms of particle acceleration and amplification of fluctuating magnetic fields with a wide dynamical range in starburst regions are discussed. Sources of cosmic rays, neutrinos and multi-wavelength nonthermal emission associated with starburst regions including potential galactic "PeVatrons" are reviewed in the global galactic ecology context.

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Section: Particle Acceleration and Non-thermal Radiation In Starburstmentioning

confidence: 99%

Nonthermal particles and photons in starburst regions and superbubbles

Bykov

2014

Astron Astrophys Rev

111

102

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“…Because any fragmentation increases a number of X-points in the current sheet, this study is also important from the point of view of particle acceleration (see, e.g., Hoshino et al 2001;Drake et al 2005;Pritchett 2008;Karlický 2008;Oka et al 2010). Namely, at the X-points particles are strongly accelerated and a high number of these X-points is needed for a sufficient volume, where particles are accelerated.…”

Section: Introductionmentioning

confidence: 99%

Fragmentation during merging of plasmoids in the magnetic field reconnection

Karlický

Bárta

Nickeler

2012

A&A

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Context. Application of the magnetic-reconnection theory onto large-scale events, such as solar flares, requires formation of very thin (kinetic-scale) current sheets within the rather thick flare current layer. Hence, some fragmentation/filamentation mechanisms has to be in action. Aims. We aim at identifying fragmentation mechanisms for magnetic field and current density structures. Namely, we focus at detailed study of the processes during the merging of plasmoids that had been formed in the current layer. Methods. A 2.5-D electromagnetic particle-in-cell model is used and its results analysed. Results. It is shown that the merging process of plasmoids is not a simple process as presented in some previous studies. On the contrary, this process leads to a complex fragmentation. We found two types of fragmentation processes: a) fragmentation in the current sheet generated between the merging plasmoids and b) fragmentation at the boundary of plasma outflow from the reconnection between these plasmoids. While the first type of fragmentation is generated by the tearing-mode (plasmoid) instability of the secondary current sheet, the second one looks to be connected with an increase of the plasma β parameter during these processes. Thus, sheared high-β plasma flows produce this additional fragmentation. Conclusions. The fragmentation and energy transport from large to small scales in a large-scale magnetic reconnection seem to be the result of interplay and positive feedback between instabilities driven by high gradients in both magnetic (intense current density) and velocity (high vorticity) fields.

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“…This gives rise to the bumpon-a-tail velocity distribution of electrons, a necessary condition for exciting Langmuir waves and radio bursts. Besides, time-scale estimates of electron acceleration based on the equations given by Drake et al [120] for contraction and by Oka et al [119] for coalescence of reconnecting magnetic islands also support the scenario that electrons are accelerated mainly by the coalescing process.…”

Section: Studies On Magnetic Islands Of Reconnections Along the Cme Cmentioning

confidence: 53%

“…A significant part of the magnetic energy is used to accelerate electrons during reconnections. Different mechanisms of electron acceleration by reconnections have been summarized in Oka et al [119]. Two important ones are called as the X type and O type.…”

Section: Studies On Magnetic Islands Of Reconnections Along the Cme Cmentioning

confidence: 99%

“…The former process corresponds to electron acceleration by induced electric field at the X-like reconnection region, and the later process refers to the electron acceleration by the rapid contraction of the O-like magnetic islands [120,121]. Recent numerical studies indicate that the coalescence of two approaching magnetic islands (also called anti-reconnection) is very efficient in electron acceleration [119].…”

Section: Studies On Magnetic Islands Of Reconnections Along the Cme Cmentioning

confidence: 99%

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A review of recent studies on coronal dynamics: Streamers, coronal mass ejections, and their interactions

Chen

2013

Chin. Sci. Bull.

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In this article I present a review of recent studies on coronal dynamics, including research progresses on the physics of coronal streamers that are the largest structure in the corona, physics of coronal mass ejections (CMEs) that may cause a global disturbance to the corona, as well as physics of CME-streamer interactions. The following topics will be discussed in depth: (1) acceleration of the slow wind flowing around the streamer considering the effect of magnetic flux tube curvature; (2) physical mechanism accounting for persistent releases of streamer blobs and diagnostic results on the temporal variability of the slow wind speed with such events; (3) force balance analysis and energy release mechanism of CMEs with a flux rope magnetohydrodynamic model; (4) statistical studies on magnetic islands along the coronal-ray structure behind a CME and the first observation of magnetic island coalescence with associated electron acceleration; and (5) white light and radio manifestations of CME-streamer interactions. These studies shed new light on the physics of coronal streamers, the acceleration of the slow wind, the physics of solar eruptions, the physics of magnetic reconnection and associated electron acceleration, the large-scale coronal wave phenomenon, as well as the physics accounting for CME shock-induced type II radio bursts. solar wind, coronal streamer, coronal mass ejection, solar radio burst, magnetic reconnection Citation:Chen Y. A review of recent studies on coronal dynamics: Streamers, coronal mass ejections, and their interactions.

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Electron Acceleration by Multi-Island Coalescence

Cited by 253 publications

References 42 publications

Nonthermal particles and photons in starburst regions and superbubbles

Nonthermal particles and photons in starburst regions and superbubbles

Fragmentation during merging of plasmoids in the magnetic field reconnection

A review of recent studies on coronal dynamics: Streamers, coronal mass ejections, and their interactions

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