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 (5) , A. Mackinnon (6) , J. Magdalenic (7) , H. Rucker (8) , J. Anderson (9) , A. Asgekar (10) , M. Avruch (11) , M. Bell (12) , J. Bentum , G. Bernardi (13) , P. Best (14) , L. Bîrzan (15) , A. Bonafede (16) , J. Broderick (17) , M. Brüggen (18) , R. Butcher , B. Ciardi (19) , A. Corstanje (20) , F. De Gasperin , E. Geus , A. Deller (21) , S. Duscha (10) , J. Eislöffel (22) , D. Engels (23) , H. Falcke (24) , R. Fender (25) , C. Ferrari (26) , W. Frieswijk (10) , M. Garrett (15) , Jean-Mathias Griessmeier (27, 28, 5) , A. Gunst (21) , M. Haarlem , E. Hassall (29) , G. Heald (21) , J. T. Hessels , M. Hoeft (30) , J. Horandel (20) , A. Horneffer (9) , E. Juette (31) , A. Karastergiou (25) , A. A. Klijn , V. Kondratiev , M. Kramer (9) , M. Kuniyoshi (9) , G. Kuper (10) , P. Maat (10) , S. Markoff (32) , R. Mcfadden (21) , D. Mckay-Bukowski (33) , J. Mckean (21) , D. Mulcahy (34) , H. Munk (21) , A. Nelles (20) , J. Norden , E. Orru (10) , H. Paas (35) , M. Pandey , V. Pandey (36) , R. Pizzo (10) , A. Polatidis (21) , D. Rafferty (15) , W. Reich (9) , H. Röttgering (15) , M. M. Scaife , J. Schwarz , M. Serylak (25) , J. Sluman (10) , O. Smirnov (37) , B. Stappers (34) , Michel Tagger (27) , Y. Tang (10) , C. Tasse (5) , S. Veen , S. Thoudam (20) , M. Toribio , R. Vermeulen (10) , J. Weeren , M. Wise (32) , O. Wucknitz (38) , S. Yatawatta (21) , P. Zarka (5) , J. Zensus

1 AIP - Leibniz-Institut für Astrophysik Potsdam
2 DSMZ - Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH / Leibniz Institute DSMZ-German Collection of Microorganisms and Cell Cultures
3 RAL - STFC Rutherford Appleton Laboratory
4 Institute of Mathematical and Physical Sciences
5 LESIA (UMR_8109) - Laboratoire d'études spatiales et d'instrumentation en astrophysique
6 LLNL - Lawrence Livermore National Laboratory
7 Solar-Terrestrial Center of Excellence, Royal Observatory of Belgium
8 IWF - Space Research Institute of Austrian Academy of Sciences
9 MPIFR - Max-Planck-Institut für Radioastronomie
10 Netherlands Institute for Radio Astronomy ( ASTRON )
11 Kapteyn Astronomical Institute [Groningen]
12 CSIRO Astronomy and Space Science
13 CfA - Harvard-Smithsonian Center for Astrophysics
14 University of Edinburgh
15 Leiden Observatory [Leiden]
16 Jacobs University [Bremen]
17 School of Physics and Astronomy [Southampton]
18 UHH - Universität Hamburg
19 MPA - Max-Planck-Institut für Astrophysik
20 Radboud University [Nijmegen]
21 ASTRON - Netherlands Institute for Radio Astronomy
22 TLS - Thüringer Landessternwarte Tautenburg
23 Hamburger Sternwarte/Hamburg Observatory
24 IMAPP - Institute for Mathematics, Astrophysics and Particle Physics
25 Oxford Astrophysics
26 LAGRANGE - Joseph Louis LAGRANGE
27 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace
28 USN - Unité Scientifique de la Station de Nançay
29 University of Southampton
30 JIVE ERIC - Joint Institute for VLBI in Europe
31 Ruhr-Universität Bochum [Bochum]
32 AI PANNEKOEK - Astronomical Institute Anton Pannekoek
33 University of Oulu
34 Jodrell Bank Centre for Astrophysics
35 Center for Information Technology CIT
36 Department of Physics and Astronomy [Ghent]
37 Department of Physics-Electronics
38 AlfA - Argelander-Institut für Astronomie

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).

Keywords: Acceleration of particles; Instrumentation: interferometers; Sun: corona; Sun: flaresSun: radio radiation; Techniques: interferometric

Domains: Sciences of the Universe [physics]

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, 2018, 611, pp.Article number A57. ⟨10.1051/0004-6361/201629017⟩. ⟨insu-01897905⟩