Probing dynamics of electron acceleration with radio and x-ray spectroscopy, imaging, and timing in the 2002 april 11 solar flare

Fleishman, G.D., Kontar, E.P. , Nita, G.M. and Gary, D.E. (2013) Probing dynamics of electron acceleration with radio and x-ray spectroscopy, imaging, and timing in the 2002 april 11 solar flare. Astrophysical Journal, 768(2), p. 190. (doi:10.1088/0004-637X/768/2/190)

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Abstract

Based on detailed analysis of radio and X-ray observations of a flare on 2002 April 11 augmented by realistic three-dimensional modeling, we have identified a radio emission component produced directly at the flare acceleration region. This acceleration region radio component has distinctly different (1) spectrum, (2) light curves, (3) spatial location, and, thus, (4) physical parameters from those of the separately identified trapped or precipitating electron components. To derive evolution of physical parameters of the radio sources we apply forward fitting of the radio spectrum time sequence with the gyrosynchrotron source function with five to six free parameters. At the stage when the contribution from the acceleration region dominates the radio spectrum, the X-ray- and radio-derived electron energy spectral indices agree well with each other. During this time the maximum energy of the accelerated electron spectrum displays a monotonic increase with time from ~300 keV to ~2 MeV over roughly one minute duration indicative of an acceleration process in the form of growth of the power-law tail; the fast electron residence time in the acceleration region is about 2-4 s, which is much longer than the time of flight and so requires a strong diffusion mode there to inhibit free-streaming propagation. The acceleration region has a relatively strong magnetic field, B ~ 120 G, and a low thermal density, ne 2 × 109 cm–3. These acceleration region properties are consistent with a stochastic acceleration mechanism.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Kontar, Dr Eduard
Authors: Fleishman, G.D., Kontar, E.P., Nita, G.M., and Gary, D.E.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Astrophysical Journal
ISSN:0004-637X
ISSN (Online):1538-4357
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
542081Rolling Programme in Solar and Plasma AstrophysicsLyndsay FletcherScience & Technologies Facilities Council (STFC)ST/I001808/1P&A - PHYSICS & ASTRONOMY