Abstract
The influence of whistlers on the distribution and gyrosynchrotron radiation of fast electrons injected into a coronal magnetic trap is considered. The kinetic equation in the Fokker–Planck approximation with consideration of fast electron scattering, both on background plasma particles and on whistlers, is solved for an inhomogeneous trap. It is supposed that the source of whistlers is a nonstationary process of flare energy release. Having found the fast electron distribution, we can calculate their gyrosynchrotron microwave emission. The influence of nonthermal electron scattering on whistlers are compared with the effects of scattering on Coulomb collisions. It is shown that whistlers considerably modify the emission characteristics of a loop at a certain energy density; in particular, they steepen the frequency spectrum. This is useful for microwave diagnostics of plasma turbulence in the flare loop.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Bespalov, P.A. and Trakhtengerts, V.Yu., O the regimes of turbulent diffusion by pitch-angles in a geomagnetic trap, Fiz. Plazmy, 1979, vol. 5, no. 2, pp. 383–390.
Bespalov, P.A., Zaitsev, V.V., and Stepanov, A.V., Consequences of strong pitch-angle diffusion of particles in solar flares, Astrophys. J., 1991, vol. 374, pp. 369–373.
Brown, J.C. and Melrose, D.B., Collective plasma effects and the electron number problem in solar hard X-ray bursts, Sol. Phys., 1977, vol. 52, no. 4, pp. 117–131.
Charikov, Yu.E. and Shabalin, A.N., Influence of magnetic turbulence on the propagation of accelerated electrons and hard X-ray brightness distribution in solar flares, Geomagn. Aeron. (Engl. Transl.), 2015, vol. 55, no. 8, pp. 1104–1111.
Charikov, Yu.E. and Shabalin, A.N., Hard X-ray generation in the turbulent plasma of solar flares, Geomagn. Aeron. (Engl. Transl.), 2016, vol. 56, no. 8, pp. 1068–1074.
Charikov, Yu.E., Mel’nikov, V.F., and Kudryavtsev, I.V., Intensity and polarization of the hard X-ray radiation of solar flares at the top and footpoints of a magnetic loop, Geomagn. Aeron. (Engl. Transl.), 2012, vol. 52, no. 8, pp. 1021–1031.
Fleishman, G.D. and Melnikov, V.F., Gyrosynchotron emission from anisotropic electron distributions, Astrophys. J., 2003, vol. 587, no. 2, pp. 823–835.
Fletcher, L. and Martens, P.C.H., A model for hard X-ray emission from the top of flaring loops, Astrophys. J., 1998, vol. 505, pp. 418–431.
Hamilton, R.J., Lu, E.T., and Petrosian, V., Numerical solution of the time-dependent kinetic equation for electrons in magnetized plasma, Astrophys. J., 1990, vol. 354, no. 1, pp. 726–734.
Hamilton, R.J. and Petrosian, V., Stochastic acceleration of electrons and effects of collisions in solar flares, Astrophys. J., 1992, vol. 398, no. 10, pp. 350–358.
Kadomtsev, B.B., Plasma Turbulence, New York: Academic, 1965.
Kaplan, S.A. and Tsytovich, V.N., Plasma Astrophysics, Oxford: Pergamon, 1973.
Kennel, C.F. and Petschek, H.E., Limit on stably trapped particle fluxes, J. Geophys. Res., 1966, vol. 71, no. 1, pp. 1–28.
Krucker, S., Battaglia, M., Cargill, P.J., et al., Hard X-ray emission from the solar corona, Astron. Astrophys., 2008, vol. 16, no. 10, pp. 155–208.
Melnikov, V.F. and Magun, A., Spectral flattening during solar radio bursts at cm-mm wavelengths and the dynamics of energetic electrons in a flare loop, Sol. Phys., 1998, vol. 178, no. 1, pp. 153–171.
Melnikov, V.F., Shibasaki, K., and Reznikova, V.E., Looptop nonthermal microwave source in extended solar flaring loops, Astrophys. J., 2002, vol. 580, no. 1, pp. 185–188.
Melnikov, V.F., Gorbikov, S.P., Reznikova, V.E., and Shibasaki, K., Relativistic electron spatial distribution in microwave flaring loops, Bull. Russ. Acad. Sci., 2006, vol. 70, no. 10, pp. 1472–1474.
Melrose, D.B. and Brown, J.C., Precipitation in trap models for solar hard X-ray bursts, Mon. Not. R. Astron. Soc., 1976, vol. 176, no. 7, pp. 15–30.
Miller, J.A., Electron acceleration in solar flares by fast mode waves: Quasi-linear theory and pitch-angle scattering, Astrophys. J., 1997, vol. 491, no. 2, pp. 939–951.
Minoshima, T., Masuda, S., Miyoshi, Y., and Kusano, K., Coronal electron distribution in solar flares: Driftkinetic model, Astrophys. J., 2011, vol. 732, no. 10, pp. 1–7.
Reznikova, V.E., Melnikov, V.F., Shibasaki, K., Gorbikov, S.P., Pyatakov, N.P., Myagkova, I.N., and Ji, H., 2002 August 24 limb flare loop: Dynamics of microwave brightness distribution, Astrophys. J., 2009, vol. 697, no. 1, pp. 735–746.
Simões, P.J.A. and Kontar, E.P., Implications for electron acceleration and transport from non-thermal electron rates at looptop and footpoint sources in solar flares, Astron. Astrophys., 2013, vol. 551, pp. 135–144.
Stepanov, A.V. and Tsap, Y.T., Electron–whistler interaction in coronal loops and radiation signatures, Sol. Phys., 2002, vol. 211, pp. 135–154.
Stepanov, A.V., Yokoyama, T., Shibasaki, K., and Melnikov, V.F., Turbulent propagation of high-energy electrons in a solar coronal loop, Astron. Astrophys., 2007, vol. 465, pp. 613–619.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Filatov, L.V., Melnikov, V.F. Influence of Whistler Turbulence on Fast Electron Distribution and Their Microwave Emissions in a Flare Loop. Geomagn. Aeron. 57, 1001–1008 (2017). https://doi.org/10.1134/S0016793217080084
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1134/S0016793217080084