Interplanetary Type III Bursts and Electron Density Fluctuations in the Solar Wind

0489280 - ÚFA 2019 RIV US eng J - Journal Article
Krupař, Vratislav - Maksimovic, M. - Kontar, E. P. - Zaslavsky, A. - Santolík, Ondřej - Souček, Jan - Krupařová, Oksana - Eastwood, J. P. - Szabo, A.
Interplanetary Type III Bursts and Electron Density Fluctuations in the Solar Wind.
Astrophysical Journal. Roč. 857, č. 2 (2018), č. článku 82. ISSN 0004-637X. E-ISSN 1538-4357
R&D Projects: GA ČR(CZ) GJ17-06818Y; GA ČR GA17-08772S; GA ČR(CZ) GA17-06065S
Grant - others:AV ČR(CZ) AP1401
Program: Akademická prémie - Praemium Academiae
Institutional support: RVO:68378289
Keywords : scattering * Sun: radio radiation * solar wind * radio-burst
OECD category: Fluids and plasma physics (including surface physics)
Impact factor: 5.580, year: 2018
http://iopscience.iop.org/article/10.3847/1538-4357/aab60f

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 <delta n(e)>/n(e) in the solar wind are 0.06-0.07 over wide range of heliospheric distances.
Permanent Link: http://hdl.handle.net/11104/0283731