MANIFESTATIONS OF ENERGETIC ELECTRONS WITH ANISOTROPIC DISTRIBUTIONS IN SOLAR FLARES. II. GYROSYNCHROTRON MICROWAVE EMISSION

Journal Article · Wed Oct 20 00:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/722/2/1577· OSTI ID:21464603

Kuznetsov, Alexey A ^[1]; Zharkova, Valentina V ^[2]

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1. Armagh Observatory, Armagh BT61 9DG (United Kingdom)
2. University of Bradford, Bradford BD7 1DP (United Kingdom)

We investigate the spectra and polarization of the gyrosynchrotron microwave (MW) emission generated by anisotropic electron beams in the solar corona. The electron distributions are selected from the steady propagation/precipitation model of beam electrons obtained from the time-dependent solutions of the Fokker-Planck equation taking into account particle anisotropic precipitation into a converging magnetic tube while losing energy in collisions and Ohmic losses induced by a self-induced electric field. We separate the effects of converging magnetic field from those of self-induced electric field for beams with different initial energy fluxes and spectral indices. The effect of returning electrons of the beam is negligible for the beams with relatively weak energy fluxes (F {approx}< 10{sup 10} erg cm{sup -2} s{sup -1}), while it becomes very important for the electron beams with F {approx}> 10{sup 12} erg cm{sup -2} s{sup -1}. Electric field-induced losses lead to the increase of MW emission intensity, especially at larger viewing angles ({theta} {approx}> 140{sup 0}, looking at the loop from a side). The polarization remains typical for the beam-like distributions. The combined effect of the self-induced electric field and converging magnetic field reveals a noticeable (up to a factor of 10) increase of the emission intensity (for the viewing angles {theta} {approx_equal} 140{sup 0}-150{sup 0}) in comparison with the models considering only collision factor, especially in the deeper precipitation layers (near the loop footpoints). Thus, considering the self-induced electric field is especially important for the resulting MW emission intensity, spectra shape, and polarization that can provide much closer correlation of simulations with observations in solar flares.

• OSTI ID: 21464603
• Journal Information: Astrophysical Journal, Vol. 722, Issue 2; Other Information: DOI: 10.1088/0004-637X/722/2/1577; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ANISOTROPY
ELECTRIC FIELDS
ELECTRON BEAMS
EMISSION
FOKKER-PLANCK EQUATION
MAGNETIC FIELDS
MICROWAVE RADIATION
SOLAR CORONA
SOLAR FLARES
SUN
TAIL ELECTRONS
TIME DEPENDENCE
ATMOSPHERES
BEAMS
DIFFERENTIAL EQUATIONS
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
EQUATIONS
FERMIONS
LEPTON BEAMS
LEPTONS
MAIN SEQUENCE STARS
PARTIAL DIFFERENTIAL EQUATIONS
PARTICLE BEAMS
RADIATIONS
SOLAR ACTIVITY
SOLAR ATMOSPHERE
STARS
STELLAR ACTIVITY
STELLAR ATMOSPHERES
STELLAR CORONAE
STELLAR FLARES