Tracking of an electron beam through the solar corona with LOFAR

G. Mann 1 F. Breitling 1 C. Vocks 1 H. Aurass M. Steinmetz 2 G. Strassmeier M. Bisi 3 R. Fallows 4 P. Gallagher A. Kerdraon A. Mackinnon 5 J. Magdalenic 6 H. Rucker 7 J. Anderson 8 A. Asgekar 9 M. Avruch 10 M. Bell 11 J. Bentum G. Bernardi 12 P. Best 13 L. Bîrzan 14 A. Bonafede 15 J. Broderick 16 M. Brüggen 17 R. Butcher B. Ciardi 18 A. Corstanje 19 F. De Gasperin E. Geus A. Deller 20 S. Duscha 9 J. Eislöffel 21 D. Engels 22 H. Falcke 23 R. Fender 24 C. Ferrari 25 W. Frieswijk 9 M. Garrett 14 Jean-Mathias Grießmeier 26, 27 A. Gunst 20 M. Haarlem E. Hassall 28 G. Heald 20 J. T. Hessels M. Hoeft 29 J. Horandel 19 A. Horneffer 8 E. Juette 30 A. Karastergiou 24 A. A. Klijn V. Kondratiev M. Kramer 8 M. Kuniyoshi 8 G. Kuper 9 P. Maat 9 S. Markoff 31 R. Mcfadden 32 D. Mckay-Bukowski 33 J. Mckean 20 D. Mulcahy 34 H. Munk 32 A. Nelles 19 J. Norden E. Orru 9 H. Paas 35 M. Pandey V. Pandey 36 R. Pizzo 9 A. Polatidis 20 D. Rafferty 14 W. Reich 8 H. Röttgering 14 M. M. Scaife J. Schwarz M. Serylak 24 J. Sluman 9 O. Smirnov 37 B. Stappers 34 Michel Tagger 26 Y. Tang 9 C. Tasse 38 S. Veen S. Thoudam 19 M. Toribio R. Vermeulen 9 J. Weeren M. Wise 31 O. Wucknitz 39 S. Yatawatta 20 P. Zarka 38 J. Zensus
Abstract : The Sun's activity leads to bursts of radio emission, among other phenomena. An example is type-III radio bursts. They occur frequently and appear as short-lived structures rapidly drifting from high to low frequencies in dynamic radio spectra. They are usually interpreted as signatures of beams of energetic electrons propagating along coronal magnetic field lines. Here we present novel interferometric LOFAR (LOw Frequency ARray) observations of three solar type-III radio bursts and their reverse bursts with high spectral, spatial, and temporal resolution. They are consistent with a propagation of the radio sources along the coronal magnetic field lines with nonuniform speed. Hence, the type-III radio bursts cannot be generated by a monoenergetic electron beam, but by an ensemble of energetic electrons with a spread distribution in velocity and energy. Additionally, the density profile along the propagation path is derived in the corona. It agrees well with three-fold coronal density model by (1961, ApJ, 133, 983).
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G. Mann, F. Breitling, C. Vocks, H. Aurass, M. Steinmetz, et al.. Tracking of an electron beam through the solar corona with LOFAR. Astronomy and Astrophysics - A&A, EDP Sciences, 2018, 611, pp.Article number A57. ⟨10.1051/0004-6361/201629017⟩. ⟨insu-01897905⟩

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