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Energetic electrons generated during solar flares

Part of: Focus on Space Plasmas Energetic Electrons

Published online by Cambridge University Press:  21 October 2015

Gottfried Mann
Gottfried Mann*
Affiliation:
Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
*
†Email address for correspondence: GMann@aip.de
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Abstract

The Sun is a giant particle accelerator. During solar flares, magnetic field energy stored in the corona is suddenly released and transferred to local heating of the coronal plasma, mass motions (e.g. jets) and the generation of energetic particles, i.e. electrons, protons and heavy ions. Basically, a flare occurs as a local enhancement of the emission of electromagnetic radiation from the radio up to the ${\it\gamma}$ -ray range on the Sun. That indicates the production of energetic electrons during flares. NASA’s RHESSI mission has the aim to investigate electron acceleration processes by studying the Sun’s X-ray and ${\it\gamma}$ -ray emission with high spatial, temporal and spectral resolution, i.e. by means of imaging spectroscopy. A substantial part of the energy released during a flare is carried by these energetic electrons. Apart from them, solar energetic particles, i.e. protons and heavy ions, and coronal mass ejections play an important role in the energy budget of a flare. Here, we focus on electron acceleration. The way in which $10^{36}$ electrons are accelerated up to energies beyond 30 keV is one of the open questions in solar physics. A flare is considered as the manifestation of magnetic reconnection in the solar corona. Which mechanisms lead to the production of energetic electrons in the magnetic reconnection region is discussed in this paper. Two of them are described in more detail.

Type
Research Article
Information
Journal of Plasma Physics , Volume 81 , Issue 6 , December 2015 , 475810601
Copyright
© Cambridge University Press 2015 

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References

Aschwanden, M. J. 2002 Particle acceleration and kinematics in solar flares – a synthesis of recent observations and theoretical concepts. Space Sci. Rev. 101, 1–227.CrossRefGoogle Scholar
Aschwanden, M. J. 2005 Physics of the Solar Corona: An Introduction with Problems and Solutions, 2nd edn. Praxis. Google Scholar
Aschwanden, M. J., Benz, A. O., Dennis, B. R. & Schwartz, R. A. 1995a Solar electron beams detected in hard x-rays and radio waves. Astrophys. J. 455, 347–365.CrossRefGoogle Scholar
Aschwanden, M. J., Kosugi, T., Hudson, H. S., Wills, M. J. & Schwartz, R. A. 1996 The scaling law between electron time-of-flight distances and loop lengths in solar flares. Astrophys. J. 470, 1198.CrossRefGoogle Scholar
Aschwanden, M. J., Schwartz, R. A. & Alt, D. M. 1995b Electron time-of-flight differences in solar flares. Astrophys. J. 447, 923.CrossRefGoogle Scholar
Aulanier, G., Janvier, M. & Schmieder, B. 2012 The standard flare model in three dimensions. I. Strong-to-weak shear transition in post-flare loops. Astron. Astrophys. 543, A110.CrossRefGoogle Scholar
Aurass, H. & Mann, G. 2004 Radio observation of electron acceleration at solar flare reconnection outflow termination shocks. Astrophys. J. 615, 526–530.CrossRefGoogle Scholar
Aurass, H., Vršnak, B. & Mann, G. 2002 Shock-excited radio burst from reconnection outflow jet? Astron. Astrophys. 384, 273–281.CrossRefGoogle Scholar
Axford, W. I., Leer, E. & Skadron, G. 1978 Acceleration of cosmic rays by shock waves. In Cosmophysics (ed. Dergachev, V. A. & Kocharov, G. E.), pp. 125–134.Google Scholar
Ball, L. & Melrose, D. B. 2001 Shock drift acceleration of electrons. Publ. Astron. Soc. Australia 18, 361–373.CrossRefGoogle Scholar
Bárta, M., Büchner, J., Karlický, M. & Skála, J. 2011 Spontaneous current-layer fragmentation and cascading reconnection in solar flares. I. Model and analysis. Astrophys. J. 737, 24.CrossRefGoogle Scholar
Battaglia, M. & Benz, A. O. 2006 Relations between concurrent hard X-ray sources in solar flares. Astron. Astrophys. 456, 751–760.CrossRefGoogle Scholar
Benz, A. O. 1987 Acceleration and energization by currents and electric fields. Solar Phys. 111, 1–18.CrossRefGoogle Scholar
Bian, N. H., Emslie, A. G., Stackhouse, D. J. & Kontar, E. P. 2014 The formation of kappa-distribution accelerated electron populations in solar flares. Astrophys. J. 796, 142.CrossRefGoogle Scholar
Brown, J. C. 1971 The deduction of energy spectra of non-thermal electrons in flares from the observed dynamic spectra of hard x-ray bursts. Solar Phys. 18, 489–502.CrossRefGoogle Scholar
Cargill, P. J. & Priest, E. R. 1982 Slow-shock heating and the Kopp–Pneuman model for ‘post’-flare loops. Solar Phys. 76, 357–375.CrossRefGoogle Scholar
Carmichael, H.1964 A process for flares. NASA Spec. Pub. 50, p. 451.Google Scholar
Chen, Q. & Petrosian, V. 2013 Determination of stochastic acceleration model characteristics in solar flares. Astrophys. J. 777, 33.CrossRefGoogle Scholar
Cliver, E. W. & Dietrich, W. F. 2013 The 1859 space weather event revisited: limits of extreme activity. J. Space Weather Space Clim. 3 (27), A31.CrossRefGoogle Scholar
Cliver, E. W. & Svalgaard, L. 2004 The 1859 solar–terrestrial disturbance and the current limits of extreme space weather activity. Solar Phys. 224, 407–422.CrossRefGoogle Scholar
Drake, J. F., Swisdak, M., Che, H. & Shay, M. A. 2006 Electron acceleration from contracting magnetic islands during reconnection. Nature 443, 553–556.CrossRefGoogle ScholarPubMed
Dulk, G. A. & McLean, D. J. 1978 Coronal magnetic fields. Solar Phys. 57, 279–295.CrossRefGoogle Scholar
Emslie, A. G., Dennis, B. R., Shih, A. Y., Chamberlin, P. C., Mewaldt, R. A., Moore, C. S., Share, G. H., Vourlidas, A. & Welsch, B. T. 2012 Global energetics of thirty-eight large solar eruptive events. Astrophys. J. 759, 71.CrossRefGoogle Scholar
Emslie, A. G., Kontar, E. P., Krucker, S. & Lin, R. P. 2003 RHESSI hard x-ray imaging spectroscopy of the large gamma-ray flare of 2002 July 23. Astrophys. J. Lett. 595, L107–L110.CrossRefGoogle Scholar
Emslie, A. G., Kucharek, H., Dennis, B. R., Gopalswamy, N., Holman, G. D., Share, G. H., Vourlidas, A., Forbes, T. G., Gallagher, P. T., Mason, G. M. et al. 2004 Energy partition in two solar flare/CME events. J. Geophys. Res. 109 (A18), 10104.Google Scholar
Fermi, E. 1949 On the origin of the cosmic radiation. Phys. Rev. 75, 1169–1174.CrossRefGoogle Scholar
Fleishman, G. D. & Toptygin, I. N. 2013 Stochastic particle acceleration by helical turbulence in solar flares. Mon. Not. R. Astron. Soc. 429, 2515–2526.CrossRefGoogle Scholar
Fletcher, L., Dennis, B. R., Hudson, H. S., Krucker, S., Phillips, K., Veronig, A., Battaglia, M., Bone, L., Caspi, A., Chen, Q. et al. 2011 An observational overview of solar flares. Space Sci. Rev. 159, 19–106.CrossRefGoogle Scholar
Forbes, T. G. 1986 Fast-shock formation in line-tied magnetic reconnection models of solar flares. Astrophys. J. 305, 553–563.CrossRefGoogle Scholar
Forbes, T. G. & Malherbe, J. M. 1991 A numerical simulation of magnetic reconnection and radiative cooling in line-tied current sheets. Solar Phys. 135, 361–391.CrossRefGoogle Scholar
Grady, K. J. & Neukirch, T. 2009 An extension of the theory of kinematic MHD models of collapsing magnetic traps to 2.5D with shear flow and to 3D. Astron. Astrophys. 508, 1461–1468.CrossRefGoogle Scholar
Grigis, P. C. & Benz, A. O. 2004 The spectral evolution of impulsive solar X-ray flares. Astron. Astrophys. 426, 1093–1101.CrossRefGoogle Scholar
Guo, J., Emslie, A. G., Kontar, E. P., Benvenuto, F., Massone, A. M. & Piana, M. 2012 Determination of the acceleration region size in a loop-structured solar flare. Astron. Astrophys. 543, A53.CrossRefGoogle Scholar
Heyvaerts, J. 1981 Solar Flare Magnetohydrodynamics. Gordon and Breach.Google Scholar
Hirayama, T. 1974 Theoretical model of flares and prominences. I: Evaporating flare model. Solar Phys. 34, 323–338.CrossRefGoogle Scholar
Holman, G. D. 1985 Acceleration of runaway electrons and Joule heating in solar flares. Astrophys. J. 293, 584–594.CrossRefGoogle Scholar
Holman, G. D., Aschwanden, M. J., Aurass, H., Battaglia, M., Grigis, P. C., Kontar, E. P., Liu, W., Saint-Hilaire, P. & Zharkova, V. V. 2011 Implications of x-ray observations for electron acceleration and propagation in solar flares. Space Sci. Rev. 159, 107–166.CrossRefGoogle Scholar
Holman, G. D. & Pesses, M. E. 1983 Solar type II radio emission and the shock drift acceleration of electrons. Astrophys. J. 267, 837–843.CrossRefGoogle Scholar
Holman, G. D., Sui, L., Schwartz, R. A. & Emslie, A. G. 2003 Electron bremsstrahlung hard x-ray spectra, electron distributions, and energetics in the 2002 July 23 solar flare. Astrophys. J. Lett. 595, L97–L101.CrossRefGoogle Scholar
Karlický, M. & Kosugi, T. 2004 Acceleration and heating processes in a collapsing magnetic trap. Astron. Astrophys. 419, 1159–1168.CrossRefGoogle Scholar
Kiplinger, A. L. 1995 Comparative studies of hard x-ray spectral evolution in solar flares with high-energy proton events observed at Earth. Astrophys. J. 453, 973.CrossRefGoogle Scholar
Kirk, J. G. 1994 Particle acceleration. In Saas-Fee Advanced Course 24: Plasma Astrophysics (ed. Kirk, J. G., Melrose, D. B., Priest, E. R., Benz, A. O. & Courvoisier, T. J.-L.), p. 225. Springer.Google Scholar
Klein, K.-L. & Trottet, G. 2001 The origin of solar energetic particle events: coronal acceleration versus shock wave acceleration. Space Sci. Rev. 95, 215–225.CrossRefGoogle Scholar
Kontar, E. P., Brown, J. C., Emslie, A. G., Hajdas, W., Holman, G. D., Hurford, G. J., Kašparová, J., Mallik, P. C. V., Massone, A. M., McConnell, M. L. et al. 2011 Deducing electron properties from hard x-ray observations. Space Sci. Rev. 159, 301–355.CrossRefGoogle Scholar
Kontar, E. P., MacKinnon, A. L., Schwartz, R. A. & Brown, J. C. 2006 Compton backscattered and primary X-rays from solar flares: angle dependent Green’s function correction for photospheric albedo. Astron. Astrophys. 446, 1157–1163.CrossRefGoogle Scholar
Kopp, R. A. & Pneuman, G. W. 1976 Magnetic reconnection in the corona and the loop prominence phenomenon. Solar Phys. 50, 85–98.CrossRefGoogle Scholar
Koutchmy, S. 1994 Coronal physics from eclipse observations. Adv. Space Res. 14, 29.CrossRefGoogle Scholar
Krucker, S. & Battaglia, M. 2014 Particle densities within the acceleration region of a solar flare. Astrophys. J. 780, 107.CrossRefGoogle Scholar
Krucker, S., Battaglia, M., Cargill, P. J., Fletcher, L., Hudson, H. S., MacKinnon, A. L., Masuda, S., Sui, L., Tomczak, M., Veronig, A. L. et al. 2008a Hard X-ray emission from the solar corona. Astron. Astrophys. Rev. 16, 155–208.CrossRefGoogle Scholar
Krucker, S., Hannah, I. G. & Lin, R. P. 2007 RHESSI and HINODE x-ray observations of a partially occulted solar flare. Astrophys. J. Lett. 671, L193–L196.CrossRefGoogle Scholar
Krucker, S., Hudson, H. S., Glesener, L., White, S. M., Masuda, S., Wuelser, J.-P. & Lin, R. P. 2010 Measurements of the coronal acceleration region of a solar flare. Astrophys. J. 714, 1108–1119.CrossRefGoogle Scholar
Krucker, S., Hurford, G. J. & Lin, R. P. 2003 Hard x-ray source motions in the 2002 July 23 gamma-ray flare. Astrophys. J. Lett. 595, L103–L106.CrossRefGoogle Scholar
Krucker, S., Hurford, G. J., MacKinnon, A. L., Shih, A. Y. & Lin, R. P. 2008b Coronal ${\it\gamma}$ -ray bremsstrahlung from solar flare-accelerated electrons. Astrophys. J. Lett. 678, L63–L66.CrossRefGoogle Scholar
Krucker, S. & Lin, R. P. 2008 Hard x-ray emissions from partially occulted solar flares. Astrophys. J. 673, 1181–1187.CrossRefGoogle Scholar
Leblanc, Y., Dulk, G. A. & Bougeret, J.-L. 1998 Tracing the electron density from the corona to 1 AU. Solar Phys. 183, 165–180.CrossRefGoogle Scholar
Leroy, M. M. & Mangeney, A. 1984 A theory of energization of solar wind electrons by the Earth’s bow shock. Ann. Geophys. 2, 449–456.Google Scholar
Lin, R. P. 1974 Non-relativistic solar electrons. Space Sci. Rev. 16, 189–256.CrossRefGoogle Scholar
Lin, R. P., Dennis, B. R., Hurford, G. J., Smith, D. M., Zehnder, A., Harvey, P. R., Curtis, D. W., Pankow, D., Turin, P., Bester, M. et al. 2002 The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI). Solar Phys. 210, 3–32.CrossRefGoogle Scholar
Lin, R. P. & Hudson, H. S. 1971 10–100 keV electron acceleration and emission from solar flares. Solar Phys. 17, 412–435.CrossRefGoogle Scholar
Lin, R. P. & Hudson, H. S. 1976 Non-thermal processes in large solar flares. Solar Phys. 50, 153–178.CrossRefGoogle Scholar
Lin, R. P., Larson, D., McFadden, J., Carlson, C. W., Ergun, R. E., Anderson, K. A., Ashford, S., McCarthy, M., Parks, G. K., Rème, H. et al. 1996 Observation of an impulsive solar electron event extending down to ${\approx}$ 0.5 keV energy. Geophys. Res. Lett. 23, 1211–1214.CrossRefGoogle Scholar
Litvinenko, Y. E. 2000 Electron acceleration by strong DC electric fields in impulsive solar flares. In High Energy Solar Physics Workshop – Anticipating Hess! (ed. Ramaty, R. & Mandzhavidze, N.), Astronomical Society of the Pacific Conference Series, vol. 206, p. 167. Astronomical Society of the Pacific.Google Scholar
Litvinenko, Y. E. & Somov, B. V. 1993 Particle acceleration in reconnecting current sheets. Solar Phys. 146, 127–133.CrossRefGoogle Scholar
Maksimovic, M., Pierrard, V. & Riley, P. 1997 Ulysses electron distributions fitted with kappa functions. Geophys. Res. Lett. 24, 1151–1154.CrossRefGoogle Scholar
Mann, G., Aurass, H., Önel, H. & Warmuth, A. 2014 On the role of slow-mode shocks in the reconnection region for generating energetic electros during solar flares. Astron. Astrophys. (submitted).Google Scholar
Mann, G., Aurass, H. & Warmuth, A. 2006 Electron acceleration by the reconnection outflow shock during solar flares. Astron. Astrophys. 454, 969–974.CrossRefGoogle Scholar
Mann, G., Jansen, F., MacDowall, R. J., Kaiser, M. L. & Stone, R. G. 1999 A heliospheric density model and type III radio bursts. Astron. Astrophys. 348, 614–620.Google Scholar
Mann, G. & Klassen, A. 2005 Electron beams generated by shock waves in the solar corona. Astron. Astrophys. 441, 319–326.CrossRefGoogle Scholar
Mann, G. & Warmuth, A. 2011 Budget of energetic electrons during solar flares in the framework of magnetic reconnection. Astron. Astrophys. 528, A104.CrossRefGoogle Scholar
Mann, G., Warmuth, A. & Aurass, H. 2009 Generation of highly energetic electrons at reconnection outflow shocks during solar flares. Astron. Astrophys. 494, 669–675.CrossRefGoogle Scholar
Massone, A. M., Piana, M., Conway, A. & Eves, B. 2003 A regularization approach for the analysis of RHESSI X-ray spectra. Astron. Astrophys. 405, 325–330.CrossRefGoogle Scholar
Masuda, S., Kosugi, T., Hara, H., Tsuneta, S. & Ogawara, Y. 1994 A loop-top hard X-ray source in a compact solar flare as evidence for magnetic reconnection. Nature 371, 495–497.CrossRefGoogle Scholar
McLean, D. J. 1985 Metre-wave solar radio bursts. In Solar Radiophysics: Studies of Emission from the Sun at Metre Wavelengths (ed. McLean, D. J. & Labrum, N. R.), pp. 37–52. Cambridge University Press.Google Scholar
Melrose, D. B. 1985 Plasma emission mechanisms. In Solar Radiophysics: Studies of Emission from the Sun at Metre Wavelengths (ed. McLean, D. J. & Labrum, N. R.), pp. 177–210. Cambridge University Press.Google Scholar
Melrose, D. B. 1994 Turbulent acceleration in solar flares. Astrophys. J. Suppl. Ser. 90, 623–630.CrossRefGoogle Scholar
Miller, J. A., Larosa, T. N. & Moore, R. L. 1996 Stochastic electron acceleration by cascading fast mode waves in impulsive solar flares. Astrophys. J. 461, 445.CrossRefGoogle Scholar
Miteva, R. & Mann, G. 2007 The electron acceleration at shock waves in the solar corona. Astron. Astrophys. 474, 617–625.CrossRefGoogle Scholar
Newkirk, G. Jr. 1961 The solar corona in active regions and the thermal origin of the slowly varying component of solar radio radiation. Astrophys. J. 133, 983.CrossRefGoogle Scholar
Oka, M., Ishikawa, S., Saint-Hilaire, P., Krucker, S. & Lin, R. P. 2013 Kappa distribution model for hard x-ray coronal sources of solar flares. Astrophys. J. 764, 6.CrossRefGoogle Scholar
Petrosian, V. & Chen, Q. 2010 Derivation of stochastic acceleration model characteristics for solar flares from RHESSI hard x-ray observations. Astrophys. J. Lett. 712, L131–L134.CrossRefGoogle Scholar
Piana, M., Massone, A. M., Kontar, E. P., Emslie, A. G., Brown, J. C. & Schwartz, R. A. 2003 Regularized electron flux spectra in the 2002 July 23 solar flare. Astrophys. J. Lett. 595, L127–L130.CrossRefGoogle Scholar
Pierrard, V., Maksimovic, M. & Lemaire, J. 1999 Electron velocity distribution functions from the solar wind to the corona. J. Geophys. Res. 104, 17021–17032.CrossRefGoogle Scholar
Priest, E. R. 1981 Solar flare magnetohydrodynamics. In Solar Flare Magnetohydrodynamics. Gordon and Breach.Google Scholar
Priest, E. R. 1982 Solar magneto-hydrodynamics. Geophys. Astrophys. Monographs 21.Google Scholar
Priest, E. R. & Forbes, T. G. 2002 The magnetic nature of solar flares. Astron. Astrophys. Rev. 10, 313–377.CrossRefGoogle Scholar
Reames, D. V., Barbier, L. M. & Ng, C. K. 1996 The spatial distribution of particles accelerated by coronal mass ejection-driven shocks. Astrophys. J. 466, 473.CrossRefGoogle Scholar
Reid, H. A. S., Vilmer, N. & Kontar, E. P. 2011 Characteristics of the flare acceleration region derived from simultaneous hard X-ray and radio observations. Astron. Astrophys. 529, A66.CrossRefGoogle Scholar
Reid, H. A. S., Vilmer, N. & Kontar, E. P. 2014 The low–high–low trend of type III radio burst starting frequencies and solar flare hard X-rays. Astron. Astrophys. 567, A85.CrossRefGoogle Scholar
Saito, K., Makita, M., Nishi, K. & Hata, S. 1970 A non-spherical axisymmetric model of the solar K corona of the minimum type. Ann. Tokyo Astron. Obs. 12, 53–120.Google Scholar
Saito, K., Poland, A. I. & Munro, R. H. 1977 A study of the background corona near solar minimum. Solar Phys. 55, 121–134.CrossRefGoogle Scholar
Schlickeiser, R. 1984 An explanation of abrupt cutoffs in the optical–infrared spectra of non-thermal sources – a new pile-up mechanism for relativistic electron spectra. Astron. Astrophys. 136, 227–236.Google Scholar
Shibata, K., Ishido, Y., Acton, L. W., Strong, K. T., Hirayama, T., Uchida, Y., McAllister, A. H., Matsumoto, R., Tsuneta, S., Shimizu, T. et al. 1992 Observations of X-ray jets with the YOHKOH soft X-ray telescope. Publ. Astron. Soc. Japan 44, L173–L179.Google Scholar
Shibata, K., Masuda, S., Shimojo, M., Hara, H., Yokoyama, T., Tsuneta, S., Kosugi, T. & Ogawara, Y. 1995 Hot-plasma ejections associated with compact-loop solar flares. Astrophys. J. Lett. 451, L83.CrossRefGoogle Scholar
Simões, P. J. A. & Kontar, E. P. 2013 Implications for electron acceleration and transport from non-thermal electron rates at looptop and footpoint sources in solar flares. Astron. Astrophys. 551, A135.CrossRefGoogle Scholar
Smith, D. M., Lin, R. P., Turin, P., Curtis, D. W., Primbsch, J. H., Campbell, R. D., Abiad, R., Schroeder, P., Cork, C. P., Hull, E. L. et al. 2002 The RHESSI spectrometer. Solar Phys. 210, 33–60.CrossRefGoogle Scholar
Somov, B. V. & Kosugi, T. 1997 Collisionless reconnection and high-energy particle acceleration in solar flares. Astrophys. J. 485, 859–868.CrossRefGoogle Scholar
Somov, B. V. & Syrovatskii, S. I. 1982 Thermal trigger for solar flares and coronal loops formation. Solar Phys. 75, 237–244.CrossRefGoogle Scholar
Speiser, T. W. 1984 Current sheet particle acceleration – theory and observations for the geomagnetic tail. Adv. Space Res. 4, 439–448.CrossRefGoogle Scholar
Speiser, T. W. & Lyons, L. R. 1984 Comparison of an analytical approximation for particle motion in a current sheet with precise numerical calculations. J. Geophys. Res. 89, 147–158.CrossRefGoogle Scholar
Sturrock, P. A. 1966 Model of the high-energy phase of solar flares. Nature 211, 695–697.CrossRefGoogle Scholar
Suzuki, S. & Dulk, G. A. 1985 Bursts of type III and type V. In Solar Radiophysics: Studies of Emission from the Sun at Metre Wavelengths (ed. McLean, D. J. & Labrum, N. R.), pp. 289–332. Cambridge University Press.Google Scholar
Treumann, R. A. & Baumjohann, W. 1997 Advanced Space Plasma Physics. Imperial College Press.CrossRefGoogle Scholar
Tsuneta, S. 1996 Structure and dynamics of magnetic reconnection in a solar flare. Astrophys. J. 456, 840.CrossRefGoogle Scholar
Tsuneta, S., Masuda, S., Kosugi, T. & Sato, J. 1997 Hot and superhot plasmas above an impulsive flare loop. Astrophys. J. 478, 787–798.CrossRefGoogle Scholar
Tsuneta, S. & Naito, T. 1998 Fermi acceleration at the fast shock in a solar flare and the impulsive loop-top hard x-ray source. Astrophys. J. Lett. 495, L67–L70.CrossRefGoogle Scholar
Vilmer, N., Krucker, S., Lin, R. P.& RHESSI Team 2002 Hard x-ray and metric/decimetric radio observations of the 20 February 2002 solar flare. Solar Phys. 210, 261–272.CrossRefGoogle Scholar
Vrsnak, B. 2003 Magnetic 3D configurations of energy release in solar flares. In Energy Conversion and Particle Acceleration in the Solar Corona (ed. Klein, L.), Lecture Notes in Physics, vol. 612, pp. 28–47. Springer.CrossRefGoogle Scholar
Wang, T., Sui, L. & Qiu, J. 2007 Direct observation of high-speed plasma outflows produced by magnetic reconnection in solar impulsive events. Astrophys. J. Lett. 661, L207–L210.CrossRefGoogle Scholar
Warmuth, A., Holman, G. D., Dennis, B. R., Mann, G., Aurass, H. & Milligan, R. O. 2009a Rapid changes of electron acceleration characteristics at the end of the impulsive phase of an X-class solar flare. Astrophys. J. 699, 917–922.CrossRefGoogle Scholar
Warmuth, A. & Mann, G. 2005 A model of the Alfvén speed in the solar corona. Astron. Astrophys. 435, 1123–1135.CrossRefGoogle Scholar
Warmuth, A., Mann, G. & Aurass, H. 2007 Constraining electron acceleration at a standing shock with HXR and radio observations. Cent. Eur. Astrophys. Bull. 31, 135.Google Scholar
Warmuth, A., Mann, G. & Aurass, H. 2009b Modelling shock drift acceleration of electrons at the reconnection outflow termination shock in solar flares. Observational constraints and parametric study. Astron. Astrophys. 494, 677–691.CrossRefGoogle Scholar
White, S. M., Benz, A. O., Christe, S., Fárník, F., Kundu, M. R., Mann, G., Ning, Z., Raulin, J.-P., Silva-Válio, A. V. R., Saint-Hilaire, P. et al. 2011 The relationship between solar radio and hard X-ray emission. Space Sci. Rev. 159, 225–261.CrossRefGoogle Scholar
Wu, C. S. 1984 A fast Fermi process – energetic electrons accelerated by a nearly perpendicular bow shock. J. Geophys. Res. 89, 8857–8862.CrossRefGoogle Scholar
Yokoyama, T. & Shibata, K. 1994 Numerical simulation of reconnection between emerging flux and coronal field. In Proceedings of Kofu Symposium, Tokyo 181, Japan, pp. 367–370. National Astronomical Observatory.Google Scholar
Zharkova, V. V., Arzner, K., Benz, A. O., Browning, P., Dauphin, C., Emslie, A. G., Fletcher, L., Kontar, E. P., Mann, G., Onofri, M. et al. 2011 Recent advances in understanding particle acceleration processes in solar flares. Space Sci. Rev. 159, 357–420.CrossRefGoogle Scholar