Interplanetary type III bursts and electron density fluctuations in the solar wind

Krupar, V., Maksimovic, M., Kontar, E.P. , Zaslavsky, A., Santolik, O., Soucek, J., Kruparova, O., Eastwood, J.P. and Szabo, A. (2018) Interplanetary type III bursts and electron density fluctuations in the solar wind. Astrophysical Journal, 857(2), 82. (doi: 10.3847/1538-4357/aab60f)

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Type III bursts are generated by fast electron beams originated from magnetic reconnection sites of solar flares. As propagation of radio waves in the interplanetary medium is strongly affected by random electron density fluctuations, type III bursts provide us with a unique diagnostic tool for solar wind remote plasma measurements. Here, we performed a statistical survey of 152 simple and isolated type III bursts observed by the twin-spacecraft Solar TErrestrial RElations Observatory mission. We investigated their time–frequency profiles in order to retrieve decay times as a function of frequency. Next, we performed Monte Carlo simulations to study the role of scattering due to random electron density fluctuations on time–frequency profiles of radio emissions generated in the interplanetary medium. For simplification, we assumed the presence of isotropic electron density fluctuations described by a power law with the Kolmogorov spectral index. Decay times obtained from observations and simulations were compared. We found that the characteristic exponential decay profile of type III bursts can be explained by the scattering of the fundamental component between the source and the observer despite restrictive assumptions included in the Monte Carlo simulation algorithm. Our results suggest that relative electron density fluctuations <δne>/ne in the solar wind are 0.06–0.07 over wide range of heliospheric distances.

Item Type:Articles
Additional Information:V.K. acknowledges support by an appointment to the NASA postdoctoral program at the NASA Goddard Space Flight Center administered by Universities Space Research Association under contract with NASA and the Czech Science Foundation grant 17-06818Y. J.S. and O.K. acknowledge the support of the Czech Science Foundation grants 17-08772S, and 17-06065S, respectively. E.P.K. was supported by an STFC consolidated grant ST/P000533/1. O.S. acknowledges support from grant LTAUSA17070. The presented work has been supported by the European Union Seventh Framework Programme (FP7/2007–2013) under grant agreement No. 606692 [HELCATS] and Praemium Academiae.
Keywords:Space and planetary science, astronomy and astrophysics.
Glasgow Author(s) Enlighten ID:Kontar, Professor Eduard
Authors: Krupar, V., Maksimovic, M., Kontar, E.P., Zaslavsky, A., Santolik, O., Soucek, J., Kruparova, O., Eastwood, J.P., and Szabo, A.
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:17 April 2018
Copyright Holders:Copyright © 2018 The American Astronomical Society
First Published:First published in Astrophysical Journal 857(2):82
Publisher Policy:Reproduced under a Creative Commons License

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
728901Consolidated Grant in Solar PhysicsLyndsay FletcherScience & Technology Facilities Council (STFC)ST/P000533/1S&E P&A - PHYSICS & ASTRONOMY