Drifting pulsating structures generated during tearing and coalescence processes in a flare current sheet

Free access article

Issue		A&A Volume 464, Number 2, March III 2007


Page(s)		735 - 740
Section		The Sun
DOI		http://dx.doi.org/10.1051/0004-6361:20065983

A&A 464, 735-740 (2007)
DOI: 10.1051/0004-6361:20065983

Drifting pulsating structures generated during tearing and coalescence processes in a flare current sheet

M. Karlický and M. Bárta

Astronomical Institute of the Academy of Sciences of the Czech Republic, 25165 Ondrejov, Czech Republic
e-mail: [karlicky;barta]@asu.cas.cz

(Received 6 July 2006 / Accepted 4 December 2006)

Abstract
Aims.Based on particle-in-cell simulations, drifting pulsating structures are interpreted as the radio emission generated during tearing and coalescence processes in the current sheet of a flare.
Methods.A 2.5D particle-in-cell electromagnetic relativistic code was used considering two versions of the model: a) the model with one current sheet with free boundary conditions and b) the model with two current sheets and periodic boundary conditions. The dispersion diagrams of electromagnetic waves we then constructed using the 2D Fourier transform.
Results.It is found that electrons are accelerated most efficiently in the region near the x-point of the magnetic field structure in the phase at the end of tearing process and at the beginning of plasmoid coalescence. The most energetic electrons are distributed mainly along the x-lines of the magnetic field structure. During these processes, Langmuir waves are generated, along with the electromagnetic (radio) ones. It looks as these electromagnetic waves can be observed mainly on the second harmonics of the plasma frequencies corresponding to the plasma densities in the external parts of the plasmoids.

Key words: Sun: flares -- Sun: radio radiation -- acceleration of particles

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