Radio echo in the turbulent corona and simulations of solar drift-pair radio bursts

Kuznetsov, A. A., Chrysaphi, N. , Kontar, E. P. and Motorina, G. (2020) Radio echo in the turbulent corona and simulations of solar drift-pair radio bursts. Astrophysical Journal, 898(2), 94. (doi: 10.3847/1538-4357/aba04a)

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Drift-pair bursts are an unusual type of solar low-frequency radio emission, which appear in the dynamic spectra as two parallel drifting bright stripes separated in time. Recent imaging spectroscopy observations allowed for the quantitative characterization of the drifting pairs in terms of source size, position, and evolution. Here, the drift-pair parameters are qualitatively analyzed and compared with the newly developed Monte Carlo ray-tracing technique simulating radio-wave propagation in the inhomogeneous anisotropic turbulent solar corona. The results suggest that drift-pair bursts can be formed due to a combination of refraction and scattering processes, with the trailing component being the result of turbulent reflection (turbulent radio echo). The formation of drift-pair bursts requires an anisotropic scattering with the level of plasma density fluctuations comparable to that in type III bursts, but with a stronger anisotropy at the inner turbulence scale. The anisotropic radio-wave scattering model can quantitatively reproduce the key properties of drift-pair bursts: the apparent source size and its increase with time at a given frequency, the parallel motion of the source centroid positions, and the delay between the burst components. The trailing component is found to be virtually cospatial and following the main component. The simulations suggest that drift-pair bursts are likely to be observed closer to the disk center and below 100 MHz due to the effects of free–free absorption and scattering. The exciter of drift pairs is consistent with propagating packets of whistlers, allowing for a fascinating way to diagnose the plasma turbulence and the radio emission mechanism.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Motorina, Ms Galina and Kontar, Professor Eduard and Chrysaphi, Dr Nicolina
Authors: Kuznetsov, A. A., Chrysaphi, N., Kontar, E. P., and Motorina, G.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Astrophysical Journal
Publisher:American Astronomical Society
ISSN (Online):1538-4357
Published Online:28 July 2020
Copyright Holders:Copyright © 2020 The Authors
First Published:First published in Astrophysical Journal 898(2): 94
Publisher Policy:Reproduced under a Creative Commons License
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
172031STFC 2015 DTPMartin HendryScience and Technology Facilities Council (STFC)ST/N504075/1P&S - Physics & Astronomy
173869Consolidated Grant in Solar PhysicsLyndsay FletcherScience and Technology Facilities Council (STFC)ST/P000533/1P&S - Physics & Astronomy
306515PHAS A&A Group STFC ConsolidatedLyndsay FletcherScience and Technology Facilities Council (STFC)ST/T000422/1P&S - Physics & Astronomy